Geocentric Science

What is daylight saving time?

Mon, 14 Dec 2009 03:16:52 +0000

Spring ahead! Fall behind! Have you ever wondered why we lose an hour in the fall and then gain an hour in the spring?

The answer lies in energy use. We use less energy in lighting if we take advantage of the daylight hours, so by adjusting the clocks by an hour, we are able to do so.

Everyone doesn’t observe Daylight Savings Time. Some places that are closer to the equator (such as Hawaii and Puerto Rico) do not observe Daylight Savings Time. They receive a lot of sunlight throughout the year, and therefore, the daylight length doesn’t vary very much. As a result, it would not make sense for these places to change their clocks.

For more information, go to About.com and Buzzle.com

Staying Organized

Wed, 16 Dec 2009 04:57:46 +0000

Staying organized is one of the key ingredients to your success in school. Follow some of these simple organizing strategies.

Date your work!

Date EVERYTHING - The easiest way to keep your notebook/binder organized is to organize it in chronological order
Write your name!

Write your name on EVERYTHING – if you happen to leave something behind or misplace your work – hopefully it will be returned to you
Hole punch all handouts!

Hole punch EVERYTHING – keep your work organized by placing it into your binder
Write your homework!

Record all of your homework assignments in your homework planner – keep it simple and record all assignments in one place

Studying Tips

Wed, 16 Dec 2009 04:59:30 +0000

A good habit to get into is to look over your notes for a minimum of 15 minutes every night. By doing so, you can address any problems and uncertainties early on.

In addition, you can highlight or take notes on your class notes in order to help you focus on the critical ideas.

Be proactive… if you have a question, seek help.

Sedimentary vs. Metamorphic Rocks. What's the difference?

Wed, 16 Dec 2009 05:00:07 +0000

Metamorphic and sedimentary rocks are very different. They form in extremely different environments. See below for some of the differences:

Metamorphic Rocks

Form deep below the Earth’s surface
Form under extreme heat and pressure
Rocks undergo re-crystallization (rocks do not melt – old bonds are broken and new bonds are created)
Banding may occur (typically alternating of light and dark minerals)
Metamorphic rocks are dense and typically very heavy for their size

Sedimentary Rocks

Form at or near the Earth’s surface
Sediments are deposited and buried. Over time, the sediments are compacted and cemented together
Low heat and low pressure
Layers of sediment are often visible
Fossils are preserved (great indicator of the geologic history of the area)

Although layering and banding imply similar concepts, banding ONLY occurs in metamorphic rocks, and layers ONLY occur in sedimentary rocks. Banding results from the intense heat and pressure that a rock is subjected to (this often results in the metamorphic rock Gneiss). The pressure forces the crystals to align themselves. Often we see alternating light and dark colored bands. The minerals separate out due to their density differences (the light colored bands are Felsic minerals, and are less dense, the dark colored minerals are Mafic minerals and are more dense).

The Rock Guide

Wed, 16 Dec 2009 16:51:01 +0000

Here’s a quick guide on how to identify a rock.

Igneous Rocks

Intrusive Igneous Rocks
- Large (visible) interlocking crystals
Extrusive Igneous Rocks
- Porous (gas pockets)
- Single color (light, medium, or dark)
- Non-crystalline (glassy)

Metamorphic Rocks

Extremely dense
Banding (foliated)
Deformed
The presence of a quartz vein, pyrite, or garnet

Sedimentary Rocks

Fossils
Layers of sediment (visible sediment)
Pieces/fragments of other rocks cemented together

Please note: Some rock samples may be polished, which does not mean that they are glassy.

Facts on Igneous Rocks

Wed, 16 Dec 2009 17:11:39 +0000

Igneous rocks can form in two environments. The first environment of formation is on/close to the Earth’s surface. These rocks are called Extrusive (Volcanic) Igneous Rocks. The molten rock (lava) cools very rapidly and therefore there is not enough time to form large interlocking crystals.

The second environment of formation is deep below the Earth’s surface. Rocks that form in this environment are known as Intrusive (Plutonic) Igneous Rocks. The molten rock (magma) cools very slowly forming well-defined, large, visible interlocking crystals (visible minerals).

A Generalized Guide for Recognizing Igneous Rocks

Wed, 16 Dec 2009 17:25:20 +0000

There are some helpful hints to keep in mind when identifying Igneous Rocks using the New York State Earth Science Reference Tables (2010 Edition). On page 6, you will find the Scheme for Igneous Rock Identification .

Texture
- Do you see vesicles (gas pockets)?
  - If yes then, the rock is glassy or fine.
  - If no, then the rock is glassy, coarse, or very coarse.
- Do you see many different colors or is the rock light, medium, or dark in color?
  - If you see many different colors such as pinks, grays, blacks, etc., you are looking at the crystals (the minerals) and the rock must have a coarse to very coarse texture.
  - If the rock is one color such as light (white, pink, to light gray), medium (light gray to dark gray), or dark (green to black), the rock has a fine or glassy texture.
Environment of Formation
- Once the crystal size has been determined, direct your attention to the left-hand side of the chart to the Environment of Formation.
- Glassy to fine textures indicate the igneous rock is an Extrusive Igneous rock (formed on the Earth’s surface and underwent rapid cooling and crystallization).
- Coarse to very coarse textures indicate the igneous rock is an Intrusive Igneous rock (formed deep below the Earth’s surface and underwent slow cool and crystallization).
Igneous Rock Name
- Using the color information from 1b and the Mineral Composition Chart, the rock name can be determined.
  - If you can see the individual crystals and if a rock is composed of mostly white, pink, and some black crystals, the rock is Felsic.
  - If you can see the individual crystals and if the rock is roughly half dark minerals and half light minerals, the rock is Intermediate.
  - If you can see the individual crystals and if the rock contains mostly black, green, and white crystals, the rock is Mafic.
  - General rules
    - 75% light minerals and 25% dark minerals = Felsic (Granite or Pegmatite)
    - 50% light minerals and 50% dark minerals = Intermediate (Diorite)
    - 25% light minerals and 75% dark minerals = Mafic (Gabbro) Greater than 75% dark minerals = Ultra Mafic (Peridotite or Dunite)
  - If you can’t see the individual crystals, the general rule is: Light (white, pink to light gray) = Felsic (Pumice, Vesicular Rhyolite, or Rhyolite) Medium (light gray to dark gray) = Intermediate (Pumice, Vesicular Andesite, or Andesite) Dark (green to black) = Mafic (Basaltic Glass, Scoria, Vesicular Basalt, or Basalt)
  - Obsidian is typically black and shinny, and has prominent conchoidal fractures

Remember

Coarse does not refer to the feel of the rock, it refers to the sizes of the minerals that the rock is composed of.

Glassy does not mean shinny. Glassy refers to the non-crystalline structure of the minerals within the rock. The rock formed extremely rapidly and therefore the minerals did not have enough time to arrange themselves into an interlocking orderly pattern.

The Importance of Studying Rocks

Wed, 16 Dec 2009 19:41:45 +0000

Rocks tell the Earth’s story! By looking at a rock, one can understand the conditions that must have been present for that rock to form. For example, by looking at the sedimentary rock shale, one is able to determine the water velocity at the time (the water must have been moving extremely slowly in order for clay to be deposited and form shale). Ripple marks indicate the direction of flow, and footprints along with other fossils indicate what organisms lived during that time period in that area.

Resistant rocks are used for architectural construction, monuments, and fertilizers. Many resistant minerals are used in ceramic and glass manufacturing (such as feldspars), can be used as insulating material in electronics (such as micas), can be used in nuclear energy (such as uranium), can be used in jewelry (quartz).

What’s the Story with Obsidian?

Wed, 16 Dec 2009 19:50:39 +0000

Obsidian is a Felsic to intermediate, extrusive igneous rock, which forms when silica-rich magma flows onto the Earth’s surface and solidifies extremely rapidly before minerals can develop and crystallize. It is classified as an amorphous solid or glass.

Obsidian often appears dark green to black in color due to minerals containing magnesium and iron as well as its non-crystalline structure. Other variations of obsidian include snow-flake obsidian and rainbow obsidian.

Why is the North Atlantic Ocean Still Cold in August?

Wed, 16 Dec 2009 20:01:27 +0000

Liquid water has one of the highest specific heat capacities. Specific heat capacity is defined as the amount of heat per unit mass needed to raise the temperature of a substance by 1˚C. Therefore, it takes a lot of energy for liquid water to change temperature. Although the northern Atlantic Ocean does heat up slightly during the summer months, the ocean is so large (and deep), that it does not get very warm. In order warm the North Atlantic Ocean, a huge amount of heat is required and several summer months of heating does not do the job.

However, you’ll notice that bodies of water in warmer climate regions are warm year round because that body of water receives a lot of intense insolation throughout the year and therefore remains warm.

Condensation on the Bathroom Mirror

Wed, 16 Dec 2009 23:42:32 +0000

Once the water is turned on in the shower, the hot, moisture-rich water will begin to evaporate warming the bathroom. However, the bathroom mirror still remains cold. When the warm, moist air touches the cold bathroom mirror condensation will occur (the mirror becomes “foggy”). The air in the bathroom is cooled to its dew point (saturation and condensation occurs).

Another example is condensation on a cold glass of water on a hot summer day. The glass surface of the cup of water provides a perfect boundary for the hot air and the cold water to meet and for the air temperature to cool to its dew point temperature.

Why are Equatorial Regions so Rainy?

Wed, 16 Dec 2009 23:48:41 +0000

Refer to the Planetary Wind and Moisture Belts in the Troposphere diagram on page 14 of the Earth Science Reference Tables

The equatorial region receives a lot of insolation throughout the day (it receives a great deal of direct sunlight), and therefore gets extremely warm. As the temperature continues to rise, evaporation will take place (evaportranspiration and evaporation from bodies of water), and the air becomes moisture-rich. During the late afternoon afternoon (early evening), the temperature will decrease increasing the humidity. If the temperature decreases enough, the dew point temperature is reached (the air is fully saturated) and if the temperature cools slightly below its dew point temperature precipitation occurs.

Liquid water has an extremely high specific heat capacity. As a result, once precipitation occurs, a huge amount of energy is released and cooling occurs. (This is one of the reasons the human body sweats.)

In addition, this weather pattern can also be explained by referring to the Planetary Wind and Moisture Belts in the Troposphere diagram. Convection cells form in the atmosphere, and the winds converge at the equator (0º), as well as at 60º North and 60º South. The rising warm, moist air cools to its dew point, resulting in precipitation.

The Ingredients for a Cloud

Wed, 16 Dec 2009 23:58:46 +0000

There are three main ingredients needed in order for a cloud to form:

The air must cool to its dew point
A condensation nuclei (dust, smoke, or ash – a place for the water vapor to condense)

Water vapor

Signs that a Storm is Approaching

Thu, 17 Dec 2009 03:45:44 +0000

A falling barometer is the first sign. A barometer is an instrument used to measure atmospheric pressure. Typically high pressure is associated with cool, dry air and low pressure is associated with warm, moist air. Water vapor weighs less than air, therefore the more water vapor present, the lower the pressure. A falling barometer indicates that water vapor is approaching (wet weather).

In addition, other common signs of an approaching storm include increasing cloud coverage, increasing intensity of the wind, and falling temperatures.

Wind

Thu, 17 Dec 2009 03:55:27 +0000

Wind is a result of the unequal heating on the Earth’s surface. The temperature differences between locations create density differences, which results in the rising, sinking, and movement of air.

All objects resonate (vibrate) at a certain frequency. Occasionally, the wind will match an object’s resonating frequency. If this occurs, the resonating will become amplified.

Here’s an example of a bridge resonating. The Tacoma Bridge

The Formation of Earth

Thu, 17 Dec 2009 03:58:53 +0000

Refer to page 10 of the Earth Science Reference Tables

Earth (as well as the other terrestrial planets) formed as rock and other space debris collided (accreted). The collisions provided a huge amount of energy and heated the planets. Many of the planets were mostly molten in their early stages.

The Earth became layered through a process known as differentiation (the heavier, denser materials sank, and the lighter, less dense materials remained at the surface). The Earth’s layers are visible in the diagram, Inferred Properties of Earth’s Interior. Notice the difference in density between the light continental crust (2.7 g/cm3) and the inner core (13.1 g/cm3).

Earth’s Layers

Thu, 17 Dec 2009 04:29:30 +0000

Refer to page 10 of the Earth Science Reference Tables

As you read in The Formation of Earth article, the Earth’s layered structure is a result of differentiation. The diagram, Inferred Properties of Earth’s Interior (from the Earth Science Reference Tables), indicates the relationship between depth, density, pressure, and temperature. The middle diagram indicates the immense pressure in the Earth’s inner core. Therefore, as depth increases pressure increases.

You might have experienced this relationship in your life if you ever swam to the bottom of a swimming pool. Although the bottom of the pool might only be six to ten feet deep, you can feel the immense weight of the water pushing down on you. However, if you swim just below the surface, you do not experience the same feeling.

The bottom diagram (temperature versus depth) also indicates that as depth increases, temperature increases. The solid line is the geothermal gradient, and the dotted line indicates the melting point, which changes as a result in composition and pressure.

The not-so Solid Earth

Thu, 17 Dec 2009 04:33:15 +0000

Refer to page 10 of the Earth Science Reference Tables

Although the Earth’s surface is composed mostly of water (the layer known as the hydrosphere), the Earth is composed of several distinct layers beneath the Earth’s surface. In the Formation of Earth article, you read about differentiation. The upper image of the Inferred Properties of Earth’s Interior shows the different layers of Earth’s structure:

Lithosphere (continental and oceanic crust)
Asthenosphere
Stiffer mantle
Outer core
Inner core

Using the bottom diagram (temperature versus depth), one can determine what the state is of each layer. The solid line represents the actual temperature (the geothermal gradient), and the dotted line represents the melting point. If the solid line is below the dotted line, it indicates that melting has not yet occurred and the material is a solid. However, if the solid line is above the dotted line, it indicates that melting has occurred and the material is a liquid. For example, the temperature of the stiffer mantle (between about 700 to 2900 km below the Earth’s surface) is below the melting point. Therefore, the stiffer mantle is solid. The temperature within the outer core is above the melting point, therefore, the outer core is a liquid.

The Big Bang Theory

Thu, 17 Dec 2009 04:36:49 +0000

The Dopper Effect shows that the Universe is expanding, and therefore the Universe must have been much smaller in the distant past. Today, scientists explain the formation of the Universe with the Big Bang Theory. A massive explosion occurred (The Big Bang), hurling the universe outwards in all directions. At this moment, time and space were created. When you look out into space, your perception of the movement of galaxies is really the Universe continuing to expand. In addition, elapsing time is really the expansion of time.

When we observe galaxies several light years away, we are really looking back in time as it was years ago.

Luminosity and Temperature of Stars

Thu, 17 Dec 2009 04:50:46 +0000

Refer to the HR Diagram (Hertzsprung-Russell Diagram) (Characteristics of Stars chart) page 15 of the Earth Science Reference Tables

This chart is also known as the HR Diagram. The HR Diagram is a plot of luminosity versus surface temperature of the stars.

The points on the diagram represent stars. Most of the stars (about 90%) fall on the main sequence (this is not a place in space but is a relationship between temperature and luminosity). As temperature increases, energy emitted increases, resulting in an increase in brightness.

Most of the stars that are not located are Supergiants, Red Giants, or White Dwarfs.

The Life Cycle of a Massive Star

Thu, 17 Dec 2009 04:55:39 +0000

Refer to the HR Diagram (Hertzsprung-Russell Diagram) (Characteristics of Stars chart) page 15 of the Earth Science Reference Tables

The formation of a very massive star (blue super giant)

“Dust”, also known as nebulae, (the accumulation of dust and gases) comes together under the force of gravity to form a PROTOSTAR.
The star is very massive, very hot, high energy, not stable, and “wants” to become stable (these stars will change most rapidly).
The star undergoes a number of reactions where hydrogen is fused into helium (fusion occurs). (Since the star is not very stable, it remains on the main sequence for a short amount of time.)
Eventually, the star will begin to pulse (the core collapses on itself several times).
The core explodes outwards in a violent shockwave known as a SUPERNOVA and collapses to form a BLACK HOLE (star collapses on itself). This takes a short amount of time (millions of years).

The Life Cycle of an Average Star (Our Sun)

Thu, 17 Dec 2009 05:02:21 +0000

Refer to the HR Diagram (Hertzsprung-Russell Diagram) (Characteristics of Stars chart) page 15 of the Earth Science Reference Tables

A star like our sun… it is AVERAGE in all aspects!

“Dust” (gases and debris) come together under the force of gravity to form a PROTOSTAR
The star has moderate mass, not very hot, moderate energy, and is relatively stable.
Evolves and remains on the main sequence for about 10 billion years
After about 10 billion years, the star becomes starts to evolve and first changes into a RED GIANT
After some time, the star pulses and explodes outwards (SUPERNOVA)
Evolves into a WHITE DWARF

To summarize…

Protostar → stable (main sequence) → red giant → white dwarf

Star Trend Definitions and Concepts

Thu, 17 Dec 2009 17:55:00 +0000

Refer to the HR Diagram (Hertzsprung-Russell Diagram) (Characteristics of Stars chart) page 15 of the Earth Science Reference Tables

Main sequence: a line on the HR diagram showing the patterns of stars when comparing luminosity and temperature and color

Luminosity: absolute (actual) brightness of a star (distance is NOT important)

Apparent brightness: the brightness that we observe (depends on size and distance)

Massive stars: blue super giants, high luminosity, large stars, VERY hot, BLUE

Low mass stars: red dwarfs, low luminosity, small stars, cool, RED

Fuel of the sun/stars: hydrogen is converted to helium (fusion)

A Quick Review on Polaris

Thu, 17 Dec 2009 19:23:50 +0000

The North Star (Polaris)

Polaris (the North Start) appears to remain stationary in the sky (because it is so far away). The other stars appear to rotate around Polaris.
The altitude of Polaris = your latitude (for example, the latitude of New York City is about 40˚, and therefore the altitude of Polaris is 40˚)

Celestial Motion

Thu, 17 Dec 2009 19:29:16 +0000

Apparent Motion

Celestial bodies such as the sun, the moon, planets, stars appear to rise in the EAST and set in the WEST.
Celestial bodies appear to move due to Earth’s rotation.

Earth’s Rotation

Thu, 17 Dec 2009 19:35:45 +0000

A quick review

360˚/24 hours = 15˚/hour
It takes the Earth 1 day to rotate on its axis
The Earth rotates counterclockwise
15˚ of longitude = 1 hour
Foucault Pendulum proves the Earth rotates!

Earth’s Revolution

Thu, 17 Dec 2009 19:41:26 +0000

A Quick Review

360˚/365 days = 1˚/day
Earth revolves around the sun counterclockwise
1 year to revolve (1 year to orbit the Sun)

Reasons for the Seasons

Thu, 17 Dec 2009 19:49:44 +0000

There are three factors that result in seasons:

The Earth’s revolution around the Sun
The Earth’s tilt on its axis
Earth is always tilted towards Polaris

Please note: the Earth’s distance from the sun does NOT influence the seasons (Earth’s orbit is nearly a circle, refer to the eccentricity value on page 15 of the Earth Science Reference Tables)

Locations on the Earth’s surface receive different amounts of solar radiation (insolation) throughout the year. Places close to the Equator receive intense insolation throughout the year and therefore do not experience a large seasonal variation.

The Earth’s tilt of 23.5º on its axis of rotation plays a very important role in seasons. Latitudes between 23.5º North through latitudes 23.5º South will receive direct insolation (the sun’s rays will hit the Earth’s surface at a 90º angle).

A Warm Cloudy Night

Sun, 20 Dec 2009 00:04:27 +0000

Have you ever wondered why it feels warmer at night when there is cloud coverage?

Clouds control the amount of insolation lost or gained by an area. During the day, clouds block some of the incoming solar radiation and thus preventing the temperature from rising that high. At night, the water vapor in the clouds block and reradiate the energy giving off by the Earth. As a result, the temperature remains warm.

Elevation and Temperature

Sun, 20 Dec 2009 00:37:30 +0000

Refer to the Selected Properties of Earth’s Atmosphere diagram on page 14 of the Earth Science Reference Tables

The troposphere is the layer of atmosphere where weather occurs. Almost all of the water vapor is confined to this layer. Within the troposphere, as elevation increases, temperature decreases. This is due to the decrease of atmospheric pressure. As air rises, it will spread out (because of the reduction in pressure or force of the atmosphere pushing down). The expanding air will cool. If the air mass cools to the dew point temperature, precipitation will likely occur.

Mountains and Precipitation

Sun, 20 Dec 2009 00:56:27 +0000

Mountains help to control the climate. Mountains can act as barriers, keeping out the cold, and can help to create deserts.

The Orographic Effect causes the windward side of mountains to receive significantly more precipitation than the leeward side of the mountain. This is observed along the Cascades Mountain Range.

Warm and moisture rich water comes off the Pacific Ocean
The air mass is blown up the windward side of the mountain
Air pressure decreases, the air mass spreads out, and the amount of molecular collisions decrease
The temperature decreases and relative humidity increases
The air mass continues to rise and cool and eventually cools to its dew point temperature, and precipitation occurs
By the time the air mass reaches the top of the mountain, it is cold and has lost most of its moisture
When the air mass begins to descend on the leeward side, air pressure increases
The air mass is compressed
The amount of molecular collisions increase
Temperature increases and relative humidity decreases
The resulting air mass is hot and dry

The Winter Solstice

Mon, 21 Dec 2009 16:55:46 +0000

In the Northern Hemisphere the winter solstice is usually December 21st or December 22nd, and the Northern Hemisphere leans 23.5º away from the Sun. As a result, the Tropic of Capricorn (23.5º South) receives direct insolation.

The Winter Solstice is the shortest day (fewest daylight hours) of the year. The Sun reaches its lowest altitude at solar noon on the Winter Solstice at latitudes equal or greater than 23.5º North.

The winter solstice marks the first day of winter.

Solstice translates to “sun stop”. The direct sunrays will not move any lower than 23.5º South, and therefore, this is the lowest boundary of the direct insolation.

The Summer Solstice

Mon, 21 Dec 2009 17:04:23 +0000

As the Earth orbits (and remains tilted at the same angle towards Polaris), on June 21st or June 22nd, the Northern Hemisphere leans towards the Sun. As a result, the Tropic of Cancer (23.5º North) receives direct insolation. The Summer Solstice is the longest day of the year (greatest daylight hours). The Sun reaches its highest altitude at solar noon on the Summer Solstice at latitudes equal or greater than 23.5º North.

The summer solstice marks the first day of summer.

Solstice translates to “sun stop”. The direct sun rays will not move any higher than 23.5º North, and therefore, this is the upper boundary of the direct insolation.

The Equinoxes

Mon, 21 Dec 2009 17:10:24 +0000

Equinox iss defined as “equal night”; therefore, on the Equinoxes, the Earth receives 12 hours of daylight and 12 hours of night.

The Equinoxes occur midway between the ends of the Earth’s orbit (midway between the Winter Solstice to the Summer Solstice and from the Summer Solstice to the Winter Solstice).

The Autumnal Equinox (Fall Equinox) occurs around September 22nd or September 23rd. The Vernal Equinox (Spring Equinox) occurs around March 20th or March 21st. The Sun’s rays hit the Equator directly (and therefore 0º receives direct insolation).

The Apparent Path of the Sun

Mon, 21 Dec 2009 17:17:30 +0000

The Sun is not actually moving throughout the day, but it is a result of Earth’s rotation that causes the Sun to appear to move throughout the sky from east to west (regardless of one’s latitude).

On the Equinoxes, the Sun always appears to rise directly in the east and sets directly in the west (on the Equinox only).

Throughout the year, the sun will rise either north of east or south of east and will set either north of west or south of west. Depending on where the sun rises and sets, will determine the apparent path length.

For example, in the Northern Hemisphere, on the Summer Solstice, the Sun will rise north of east and will set north of west. The sun rises high in the sky resulting in a long path (many daylight hours) and lots of warming.

On the other hand, in the Northern Hemisphere, on the Winter Solstice, the Sun’s apparent path is short; the sun does not rise high in the sky and results in few daylight hours (little warming).

Kepler's Second Law

Wed, 23 Dec 2009 22:45:26 +0000

Refer to the Equations on page 1 and the Solar System Data on page 15 of the Earth Science Reference Tables

Law of Equal Areas - Opposite Segments are Equal in Area

(Not Drawn to Scale)

Planets do not move at a constant velocity. However, since Area #1 = Area #2, the planet will travel the same amount of area in equal periods of time. In order for this to occur, the planet must travel at different speeds throughout its orbit.

Perihelion occurs when the planet is closest to the Sun and the planet is going fastest (occurs in January).

Aphelion occurs when the planet is furthest from the Sun and the planet is going slowest (occurs July).

A Quick Review of Weather Station Models

Wed, 23 Dec 2009 22:54:50 +0000

Refer to Pressure Table and Weather Map Symbols on page 13 of the Earth Science Reference Tables

Here is an example:

What is the wind direction and wind speed?

Answer: From the northwest at 25 knots

Explanation: The wind feathers are located in the northwest quadrant. Wind is always described as the direction in which it blows from.
What is the temperature (dry bulb temperature)?

Answer: 39ºF

Explanation: Temperature is located on the upper left side of the station model
What is the dew point? Is precipitation likely? Why or why not?

Answer and Explanation: 38ºF, precipitation is very likely because the air must cool by only 1ºF in order to reach the dew point and for the air to be 100% saturated. Also, there is 100% cloud coverage.
What is the decoded pressure?

Answer: 986.5 mb

Explanation: You need to decide whether or not to put a 9 or a 10 in front of the 865 and then move the decimal over one place to the left. It’s either 986.5 mb or 1086.5 mb. Looking at the Pressure chart on page 13 of your Earth Science Reference Tables, you will see that 1086.5 mb is too high (does not fit on the chart) and therefore the correct answer is 986.5 mb.
What is the barometric trend?

Answer: -1.0 mb and falling

Explanation: The barometric trend is located in the middle of the station model on the right side. The – symbol indicates that the barometric pressure has falling in the past 3 hours by 1.0 mb. 10 represents the coded barometric pressure. To decode the pressure, move the decimal place over one place to the left. The \ symbol indicates that the pressure is steadily falling.
What was the barometric pressure 3 hours ago?

Answer: 987.5 mb

Explanation: Since the barometric pressure has fallen over the past 3 hours, I know that it was higher 3 hours ago than what it is now. It was 1.0 mb higher 3 hours ago so 986.5 mb + 1.0 mb = 987.5 mb
What type of pressure system is approaching? What kind of weather is associated with this pressure system?

Answer: A low-pressure system (or a cyclone).

Explanation: The falling barometric pressure indicates that warm, moist air is approaching. This type of weather is associated with a low-pressure system.

The Doppler Effect

Wed, 23 Dec 2009 23:28:40 +0000

The Doppler Effect is a change in pitch (frequency) due to an object’s motion – the wavelength changes causing the pitch to change.

As an object emits sound or light, and as the object moves towards or away from an observer, the wavelength changes. If an object is moving towards an observer, the wavelength will become shorter (higher pitched), creating a blueshift. Otherwise, if the object is moving away from an observer, the wavelength will become longer (a lower pitch), creating a redshift.

Proving that the Universe is Expanding

Wed, 23 Dec 2009 23:38:01 +0000

Stationary Object Emitting Sound/Light

The object emits wavelengths that are equal because object is NOT moving. Therefore, the same wavelength (same frequency) observed no matter where the observer is located.

Object is Moving (Slower than the Speed of Sound/Light)

All wavelengths are not equal and therefore different frequencies (pitches) will be observed (heard or seen).

Position A: Object is moving away from the person; wavelength is long (low frequency, low pitch) and a red light is observed. This is known as the Redshift.

Position B: Object is moving towards the person; wavelength is short (high frequency, high pitch) and a blue or violet light is observed. This is known as the Blueshift.

The Red Shift

Astronomers see red light when looking at distant galaxies and therefore, galaxies are moving away from us. This is known as the Redshift (long wavelength’s) and this proves that since the Big Bang, the universe has been expanding.

Spectral/Emissions Lines and the Expanding Universe

Sat, 26 Dec 2009 21:42:29 +0000

Scientists learn about the radiation given off by space by using a spectrometer and measuring the radiation frequency of gases. This optical telescope can detect visible light. Each gas produces a certain line pattern, and this is considered the gas’ fingerprint. Each gas has its own line pattern (or fingerprint).

For example, below are two sets of spectral lines. #1 represents lab spectral lines for hydrogen gas. #2 represents spectral lines of hydrogen gas from a distant galaxy.

Lab and galaxy lines are not aligned. The galaxy lines are shifted towards the right or towards the red end of the spectrum and therefore, there is a redshift and the galaxy is moving away from us (Earth).

Depending on how much the spectral lines are shifted, will determine the velocity (speed) in which the galaxy is moving away from us.

The Milky Way Galaxy

Sat, 26 Dec 2009 22:10:54 +0000

Refer to the Solar System Data on page 15 of the Earth Science Reference Tables

Our solar system consists of eight planets (refer to page 15 for the list of planets). The sun is the located at the center of our solar system, and each of the planets orbit around the sun.

There are many stars and solar systems within our galaxy. We are part of the Milky Way Galaxy. The Milky Way is a spiral galaxy that consists of approximately 200 to 400 billion stars, and our solar system is located on one of the arm’s.

Although the age of the Milky Way Galaxy is difficult to determine, it has been estimated to be approximately 13.2 billion years old (about the age of the universe).

Image from Wikipedia

The Northern Lights

Sun, 27 Dec 2009 02:58:50 +0000

Are also known as Auroras or Aurora Borealis, which occur in high latitudes. Charged particles are emitted from the sun and are funneled into the upper atmosphere (known as the ionosphere) by the Earth’s magnetic field. The particles collide and their energy level changes. The color variation is the result of different elements being excited and returning to their ground state.

Lake Effect Snow Storms

Mon, 28 Dec 2009 00:38:40 +0000

During the winter, cold dry (very low relative humidity) air develops over Canada. This air mass is known as continental polar (cP). The cP air mass will move down towards the United States. As the air mass travels over the Great Lakes, the air is warmed (water has a higher specific heat capacity than land, refer to the article Why is the North Atlantic Still Cold in August?), and the relative humidity increases.

Once the air mass reaches land, the temperature decreases (due to land’s low specific heat capacity), the air cools to its dew point temperature, and precipitation occurs.

Earth’s Magnetic Field

Fri, 01 Jan 2010 20:48:53 +0000

Particles of rock accreted together to create the early Earth. This young Earth looked extremely different from what it does today. Young Earth was a fiery planet; it was a rotating mass of hot gases and minerals, revolving around the Sun, which eventually began to cool and undergo differentiation (refer to The Formation of Earth, Earth’s Layers, and The not-so Solid Earth articles).

Before the Earth underwent differentiation, there was a magnetic fields in the young Earth. As more rock accreted into the primitive Earth, the iron grains within the rock became magnetize. The Coriolis Effect and convection within the molten core caused the iron to move. This resulted in an electric current, which created a stronger magnetic field.

The Earth developed a Magnetic North Pole and a Magnetic South Pole. The Magnetic Poles are the two positions where the Earth’s magnetic field is vertical. Presently, Earth’s Magnetic North Pole is located near the Geographic North Pole (also known as True North) and the Magnetic South Pole is located near the Geographic South Pole. Since the Magnetic North Pole and True North are not aligned, this is known as Magnetic Declination.

Image from Wikipedia

The Earth’s magnetic field (also known as the magnetosphere) extends far out into space.

Solar Wind and the Magnetosphere

Fri, 01 Jan 2010 22:14:03 +0000

Charged particles are continuously emitted from the Sun in the form of Solar Wind. The temperature and speed of the particles will determine the force the particles are ejected from the Sun.

The Solar Winds could be extremely dangerous for Earth and all of its organisms. However, the Earth has a protection shield, known as the Magnetosphere (refer to the Earth’s Magnetic Field article).

As the Solar Wind approaches Earth (or other planets that have a magnetic field, such as Jupiter and Saturn), the Solar Wind is deflected away from Earth, and extends out like a tail on the side of the Earth facing away from the sun. The picture below, illustrates the tail on the right side.

Image from Wikipedia

Some of the charged particles are trapped with the Earth’s Magnetic Field in regions known as the Van Allen Radiation Belts. Charged particles moving through the atmosphere can create Auroras. The charged particles are funneled down to the Poles.

The Coriolis Effect

Fri, 01 Jan 2010 23:30:36 +0000

Refer to the diagrams Surface Ocean Currents on page 4 and the Planetary Wind and Moisture Belts in the Troposphereof the Earth Science Reference Tables

Fluids, such as atmospheric winds and bodies of water, will flow from regions of high pressure to regions of low pressure on the Earth’s surface. Large-scale fluid systems will appear to move in a curved path due to the Earth’s rotation, the curvature of the Earth, and the differences in the rotational speed. If the Earth was not rotating, the path of movement would be a straight line.

The large-scale circular patterns are known as gyres. In the Northern Hemisphere, winds are deflected to the right and the gyres flow clockwise. In the Southern Hemisphere, winds are deflected to the left and the gyres flow counterclockwise.

There is a common misconception that the Coriolis Effect influences water flow down the drain of a bathtub or a toilet. However, these fluid systems are too small to be affected by the Coriolis Effect.

The Dynamic Earth

Sun, 03 Jan 2010 21:34:50 +0000

Earth’s crust (or lithosphere) is continually moving and changing; mountains and volcanoes are created and then worn away. Today, we see evidence of the dynamic planet in the form of volcanic eruptions, displaced structures, tilted and deformed rocks, sedimentary rocks layers at high elevations, and earthquakes.

Evidence of Ocean Floor Spreading

Sun, 03 Jan 2010 22:19:43 +0000

Research gathered in the 1950s lead Professor Harry Hess to propose the idea of seafloor spreading.

However, before Harry Hess, Alfred Wegner first purposed the idea of continental drift. The Theory of Plate Tectonics was built upon these ideas.

Mid-Ocean Ridge: Large-underwater mountain chains are found in all ocean basins. These mountain ranges are the result of a divergent plate boundary, where the Earth’s crust is ripped apart as magma rises and forces the lithosphere apart. The older rock is pushed away from the oceanic ridge. The largest mountain range on Earth is the Mid-Atlantic Ridge.
Rock Age: The rocks that make-up the ocean floor (oceanic crust) are significantly younger than the rocks that make up the continents (continental crust). In addition, the youngest oceanic rocks are found at the mid-ocean ridge and increase in age as distance from the ridge increases. The age of the oceanic rock on one side of the ridge is equal to the age of the oceanic rock on the other side of the ridge at that same distance away from the ridge.
Paleomagnetism: The mafic oceanic rock (primarily basalt) contains iron minerals. As the lava cools and solidifies, the iron crystals align themselves with the Earth’s magnetic field. The oceanic rocks show that the Earth’s magnetic field has reversed many times throughout Earth’s history. The reversals can be seen in rocks on either side of the ridge. The rocks on one side of the ridge show the Earth’s magnetic field at the time of their formation. This pattern can be observed on the other side of the ridge at the same distance away from the ridge.
Trenches: The old oceanic crust is pushed away from the oceanic ridge as magma rises to form new rocks at the ridge. Eventually, the oceanic crust is destroyed in a trench. Trenches form when dense rock is forced downwards into the asthenosphere. The plunging oceanic crust grinds and melts as it is forced deeper and deeper into the Earth. Earthquakes and volcanoes are a result of the suducting oceanic crust. (Read more on subduction in the Plate Boundaries article.)

Stream Features and Velocity - A Quick Review

Thu, 14 Jan 2010 03:39:10 +0000

Running water plays a huge role in shaping the Earth’s surface and is considered a powerful agent of erosion.

Streams and rivers slowly change the surrounding landscape by weathering and eroding the underlying bedrock. Running water also has the power to quickly modify the Earth’s surface (especially during flooding events).

Common stream features include: meanders, oxbow lakes, meander scars, point bars, cut banks, floodplains, natural levees, deltas, and alluvial fans. Additionally, the velocity of the river or stream plays an important role in determining the shape of the river and the features that surround the river.

What is a meander? How does it form?

Answer: Meanders are the “s” shaped patterns (the curved looping pattern) that a river or stream makes as it travels from high elevation to lower elevation. Over many years, the river or stream carves its way into the less resistant rock by weathering and eroding the bedrock and creating the stream or river channel.
What is an oxbow lake?

Answer: Over time, as a result of weathering an erosion on the outer edges of the meander, the meanders will eventually come together. The stream will form a new shorter channel (and will not flow around the meander, thus leaving behind an abandoned meander). The water will flow through the steeper and straighter path. Eventually, the old meander (abandoned meander) will become separated from the stream, leaving behind a lake (an oxbow lake).
What is a meander scar?

Answer: Since water is no longer flowing into the oxbow lake, it eventually dries up. This old, dried-up lake is known as a meander scar.
What is a point bar and cut bank?

Answer: There are two important features of a meander; the inner and outer sides. The water velocity is slower on the inner side of a meander. Therefore, deposition dominates (sediments are put down or settle out of the water column). Point bars are also known as beaches. However, the water is has a greater velocity on the outer side of the meander, and therefore, erosion dominates (water is moving quickly and can pick up and transport more sediment).
What is a floodplain?

Answer: During a flood, a stream or river transports more sediment and water. The stream or river spills water and sediment on either sides of the channel. This process decreases the water velocity, and allows deposition to take place. This process forms a floodplain.
What are natural levees?

Answer: During a flood, sediment will spill over the stream or river’s channel to create a floodplain. However, most of the larger sediment will collect closest to the stream (along the banks) to form a natural levee (a build-up of coarser sediment on along the channel).
What are deltas and alluvial fans?

Answer: As a fast flowing stream or river flows into a slower moving body of water (such as a lake, sea or ocean), deposition occurs (due to the decrease in water velocity). This occurs at the mouth of a stream and results in a fan shaped pile of sediment known as a delta. Alluvial fans form when a stream or river flows down a steep mountain valley and reaches flat open land and deposition occurs. The picture below shows an alluvial fan.
What controls stream velocity?

Answer:

A. The amount of water a stream or river is carrying

B. The size of the channel

C. The gradient (steeper land = faster velocity)

D. The amount of water, the size of the channel, and the gradient will affect the types of stream features that are observed.

Glaciers

Thu, 14 Jan 2010 04:12:47 +0000

Glaciers are large masses of ice that flow downwards due to gravity. Glaciers are an important agent of erosion and have played a key role in shaping the Earth’s surface. Although, we only find glaciers at high elevations and in polar regions today, glaciers covered New York State until about 10,000 years ago (the end of the last Ice Age). Glaciers are responsible for the formation of the Great Lakes, the Hudson River Valley, along many other features.

Glaciers modify the landscape as they transport huge amounts of sediment and drag the debris over the Earth’s surface. As the glacier moves downwards, it carries, pushes, and drags sediments ranging in size. This abrades (smooths) the surface.

What are indicators that a glacier was present?

Answer:

A. Striations

B. Glacial Polish

C. Dumlins

D. U-Shaped Valleys

E. Unsorted sediment

F. Moraines

G. Glacial erratics

H. Cirques, Aretes, and Horn peaks

Earthquakes

Tue, 19 Jan 2010 23:12:23 +0000

Refer to the Tectonic Plates diagram on page 5 of the Earth Science Reference Tables

An earthquake is the shaking or trembling of the Earth’s surface. Most earthquakes are the result of sudden movement along a fault (planes of weakness in the crust). Earthquakes can also be caused by volcanic eruptions, as well as human activity (such as explosions).

Along plate boundaries and other locations where there is movement of the Earth’s crust, the rock is under immense stress. The rock will pull and stretch until it can no longer be stressed. At this point, the rock will break (or snap). This causes an earthquake. The pulling of rock and the buildup of stress within the rock is known as the Elastic Rebound Theory, and once the rock is broken, the rock’s elastic limit was reached. Once the elastic limit has been reached, the rock will snap back or rebound creating aftershocks. Earthquakes relieve the built-up stress within the rock.

The point where the rock breaks is known as the focus, and the epicenter is the point on the Earth’s surface directly above the focus. Seismic waves are first felt at the epicenter.

The same phenomena can be observed in a rubber band. The rubber band can be stretched, but at a certain point, it will break (the elastic limit) and snap back (rebound).

Seismic Waves

Tue, 19 Jan 2010 23:35:11 +0000

Refer to the Tectonic Plates diagram on page 5 and the Inferred Properties of Earth’s Interior diagram on page 10 of the Earth Science Reference Tables

Seismic waves are also known as earthquake waves. Once rock reaches its elastic limit, and the rock snaps back and forth releasing the built-up stress, energy is released. The energy (or vibrations) are transmitted through the rock outwards in all directions.

What are the different seismic waves?

Answer: There are surface waves (transport energy along the Earth’s surface), and body waves (transport energy through the body of Earth). There are two types of body waves, transverse waves and longitudinal waves.
What are P-waves?

Answer: P-waves are also known as longitudinal waves, and alternate between compression and expansion in the same direction that the wave is traveling. P-waves are also known as primary waves because they are the first waves to reach a seismograph after an earthquake. P-waves travel faster than the other seismic waves and can travel through solids, liquids, and gases (all three states of matter can be compressed and expanded). The velocity of P-waves will increase as it moves through denser material.

Image from Wikipedia
What are S-waves?

Answer: S-waves are also known as transverse waves or shear waves, and twist the rock back and forth. S-waves deform rock and travel perpendicular to the direction of travel. S-waves arrive second (they are secondary waves) to a seismograph station. S-waves can only travel through solids.

Images from Wikipedia
What are the types of body and surface waves?

Answer: There are two types of body waves, P-waves and S-waves. Additionally, there are two types of surface waves, Love waves (L-waves), and Rayleigh waves. The surface waves do the most damage to the structures on the Earth’s surface.
Why are P-waves and S-waves important?

Answer:

A. Seismic waves provide information about the Earth’s interior. After an earthquake, P-waves can be detected almost at all seismographs around the world. However, this is not the case for S-waves; S-waves disappear completely. (The zones in where seismic waves cannot be detected is known as a shadow zone). Is information was used to prove that the Earth must consist of different states of matter (solids, liquids, and gases). Since P-waves are detected throughout the world, they can travel through all states of matter. S-waves disappear, and therefore can only travel through solids.

Image from Wikipedia

B. P-wave and S-wave information can be used to help scientists determine the distance to the epicenter of an earthquake.

C. Scientists can use seismic wave information to look at earthquake trends and patterns and in order to detect danger zones.

Plate Boundaries

Wed, 20 Jan 2010 22:44:40 +0000

Refer to the Tectonic Plates diagram on page 5 and the Inferred Properties of Earth’s Interior diagram on page 10 of the Earth Science Reference Tables

The Earth’s plates move as a result of convection currents within the mantle. The moving plates create earthquakes where the plates meet and where they are ripped apart. (Refer to the Earthquakes article).

There are three types of plate boundaries. These include:

Convergent Plate Boundaries
- Two or more tectonic plates come together (the plates converge). Crust is destroyed and earthquakes occur.
- What are the different types of convergent boundaries?
  
  Answer:
  
  A. Continental Crust and Oceanic Crust converge. Since continental crust has a lower density than oceanic crust, the continental crust is forced upwards in the collision and the oceanic crust subducts (is forced downwards). An oceanic trench is created. As the oceanic crust is forced downwards into the mantle it begins to melt. The melted rock (magma) will rise to the Earth’s surface to create volcanoes. The continental crust buckles and crunches as it collides with the oceanic crust and is forced upwards to create mountains. The highest mountains in the world are created this way.
  
  B. Oceanic Crust and Oceanic Crust converge. Since both slabs of crust are equal in density, both slabs of crust subduct. This plate boundary creates some of the deepest trenches known. As the subducting crust is forced into the mantle, it will melt. The hot plum of magma will rise towards the Earth’s surface (due to the lower density), and create a volcano. The continental crust crunches and buckles as it collides with the oceanic crust. The continental crust is forced upwards to create mountains.
  
  C. Continental Crust and Continental Crust converge. Since both slabs of continental crust are equal in density, and both are relatively light, neither slab subducts. Instead, both are forced upwards. This type of plate boundary creates extremely high mountains.
- What are examples of convergent boundaries?
  
  Answer:
  
  A. South American Plate is colliding with the Nazca Plate (Continental Oceanic Plate Boundary)
  
  B. The Philippine Plate is colliding with the Pacific Plate (Oceanic Oceanic Plate Boundary)
  
  C. The Eurasian Plate is colliding with the Indian-Australian Plate to create the Himalayas (Continental Continental Plate Boundary)
Divergent Plate Boundaries
- Two tectonic plates are pulled apart (the plates diverge). Crust is created and earthquakes occur.
- What are examples of a divergent plate boundary?
  
  Answer: The Pacific Plate is moving away from the Nazca Plate to create the East Pacific Ridge.
  
  Indian-Australian Plate is moving away from the Antarctic Plate to create the Southeast Indian Ridge.
  
  The Eurasian Plate is moving away from the North American Plate to create the Mid-Atlantic Ridge. Iceland was formed as a result of volcanic eruptions along the plate boundary. In April 2010, there were a series of significant volcanic eruptions. The volcanic eruptions caused air traffic problems, and airplanes were not allowed to fly due to the huge amount of ash and volcanic debris in the air traffic lanes. The Boston Globe has some great images of the eruption.
Transform Plate Boundaries
- Two tectonic plates grind past one another (they become offset). Crust is not created and not destroyed. Relative shallow and larger magnitude earthquakes occur.
- What are examples of a transform plate boundary?
  
  Answer: The San Andreas Fault (west coast of the United States), and the Enriquillo Fault in the Caribbean (created the Earthquakes in Haiti in January 2010 Haiti Earthquake)

The Theory of Plate Tectonics

Thu, 21 Jan 2010 02:49:30 +0000

Refer to the Tectonic Plates diagram on page 5 and the Inferred Properties of Earth’s Interior diagram on page 10 of the Earth Science Reference Tables

By the 1960s, there was enough evidence to support seafloor spreading (refer to Evidence of Ocean Floor Spreading). However, scientists also knew that the entire crust was not capable moving in all directions at once if it was a solid shell. The Theory of Plate Tectonics was born in order to explain the movement of the lithosphere and scientists determined that the lithosphere must consist of tectonic plates.

What is the evidence that supports the Theory of Plate Tectonics?

Answer:

A. The oceanic crust is significantly younger than the continental crust (therefore, the oceanic crust is created and destroyed more quickly than the continental crust).

B. Earth’s magnetic field has been preserved in the oceanic rock. The rock shows that there have been many magnetic field reversals throughout Earth’s history.

C. There are three types of plate boundaries: convergent, divergent, and transform. New seafloor is created at divergent plate boundaries (the mid-ocean ridges) and destroyed at convergent plate boundaries (trenches). Therefore, Earth is not getting bigger or smaller (crust is being created at the same rate that it’s being destroyed).

D. Volcanic activity is associated with plate boundaries, and the Ring of Fire is the result of the plate boundaries that surround the Pacific Ocean. Image from Wikipedia

E. Convection currents (rising and sinking of magma due to density differences) in the mantle provide the driving force that cause the plates to move.

F. Convection currents produce hot spots
What are tectonic plates?

Answer: The lithosphere (the Earth’s surface) is broken into large, rigid slabs (or plates) of rock. (There are approximately six large slabs and several smaller pieces.) The plates move independently of one another as a result of convection currents within the asthenosphere.
What are hot spots and how do they form?

Answer: A plume of magma rises from deep within the mantle through the lithosphere. The plume creates a volcano, and as the lithospheric plate moves over the plume of magma, a chain of islands can form. Hot spots are observed in the center of a tectonic plate (away from a plate boundary).
What are examples of hot spots?

Answer: The Hawaiian Islands, the Galapagos Islands, and Yellowstone National Park, formed as a result of a plume of magma rising up from the mantle.

Continental Drift

Thu, 21 Jan 2010 23:59:34 +0000

In the early 1900s, Alfred Wegner introduced the idea of continental drift. This theory had four main components.

The continents look like they fit together like a puzzle and then drifted apart. When all of the continents fit together, they formed one original landmass (or a super continent) known as Pangaea.
There are similar rock types, fossils, plants, and glacial remnants on the matching shorelines of the continents.
There are fossils of tropical plants and animals in polar regions. There are also fossils of polar plants and animals in tropical regions. This indicates that the continents must have moved or shifted position since those plants and animals lived.
The continental crust and oceanic crust differ in depth. The continental crust is thick and consists of granite (low density igneous rock). The oceanic crust is thin and consists of basalt (high density igneous rock). Wegner purposed that there are two levels of crust because:
- The crust floats on top of the hot mantle
- The continents are higher because the less dense continental crust sits and floats on top of the more dense material.
The drifting was the result of the blocks of crust simply moving away from one another.

The Agents of Erosion

Wed, 10 Feb 2010 19:27:42 +0000

Erosion is the removal and transportation of rock or sediment. There are five natural agents (methods) of erosion driven by gravity.

Mass wasting/Landslides
Running Water and Groundwater
Ocean Currents
Wind
Glaciers
Humans

Mass Wasting/Landslides

Wed, 10 Feb 2010 20:03:44 +0000

Mass wasting is defined as the downhill movement of sediment due to gravity. There are several important forces that determines whether or not an object will move. There is a downward force and an opposing frictional force (upward force). Depending on which force is greater (the downward force or the frictional force), will determine if the object or sediment will move. If the frictional force is greater than the downward force, the object remains stationary.

How does the slope of a hill affect mass wasting?

Answer: As the slope gets steeper, there is a greater downward force. This increases the chances of mass wasting.
What is the angle of repose?

Answer: The angle of repose is defined as the steepest angle that sediment will remain stable. The size, shape, and density of the sediment influence the angle of repose. Once the angle is exceeded, mass wasting (or a landslide) will occur.
What is a landslide?

Answer: A landslide is a general term used for any mass wasting event. There are several types of both rapid mass wasting as well as slow mass wasting.
What are examples of rapid mass wasting?

Answer:

- Rockfalls: Rock pieces are broken off by weathering and fall down the steep slopes of a mountain. Rockfalls are common along highways or in mountainous areas.

- Rockslides (or Block slides): Occur on less steep slopes than rockfalls. During a rockslide, debris slides downward and are often triggered by heavy rains (the water provides a smooth surface for the debris to move over) or earthquakes (sediment is broken apart and become unstable).

- Slumps: Masses of rock or soil slides down the cliff in one slab (or piece). Slumps occur because the sediment slides down a curved plane of weakness.

- Mudflows: Are mixtures of rock, soil and water. Mudflows typically occur after heavy rains and over surface that has little or no vegetation (the vegetation holds the soil in place).
What are examples of slow mass wasting?

Answer: Slow mass wasting typically occurs in more humid areas where the slopes are covered in vegetation. The vegetation holds the soil and sediment together. However, mass wasting will occur, but will occur much more slowly.

- Earthflow: A shallow layer of soil and sediment slowly slides downwards.

- Soil Creep: Vegetation and surface features (such as fences and walls) moves downhill extremely slowly. Frost action is one of the main contributors to soil creep.

Atmospheric Circulation

Tue, 23 Feb 2010 21:55:36 +0000

Refer to the diagram Planetary Wind and Moisture Belts in the Troposphere diagram on page 14 of the Earth Science Reference Tables

Image from Wikipedia

Atmospheric circulation is the result of two factors. The first is unequal heating of the Earth’s surface. The second factor is the Earth’s rotation, which causes the Coriolis Effect. Both factors produce prevailing winds and belts of low and high pressure systems from the equator to the poles.

Equatorial regions receive more insolation (solar radiation) throughout the year than polar regions. The air over the equator becomes warm and water evaporates. The equatorial air is warm and moist and forms a low pressure belt. The equatorial air has a low density and rises. As it moves upwards, it expands, cools to its dew point temperature, and precipitation occurs. Cool, dense air moves in to replace the displaced air. This creates a circulation pattern known as a convection cell.

There are three convection cells on either side of the Equator. Warm air rises at the equator (0º) and sinks at 30º North and 30º South. The sinking air mass is dry and forms a high pressure belt (deserts form at this latitude). The air mass at 60º North and 60º South is less dense and rises, and forms a low pressure belt (high amounts of precipitation occur at this latitude). The air mass sinks at 90º North and 90º South and forms a high pressure belt (low amounts of precipitation, and desert conditions occur at this latitude).

Three distinct convection cells form as a result of the Earth’s rotation. If the Earth did not rotate (and if the Earth was composed of uniform material), there would be one convection cell. Air would rise at the equator and sink at the poles. However, since the Earth rotates, one large convection cell is not possible (the convection cell would be extremely unstable and would break down immediately to form three separate cells).

Each convection cell has a prevailing wind system. From 0º to 30º (north and south of the equator), the Trade Winds form, from 30º to 60º (north and south of the equator), the Westerlies form, and from 60º to 90º (north and south of the equator), the Polar Easterlies form. These wind systems move as a result of the Coriolis effect (sinking and rising air is deflected to the right in the Northern Hemisphere and is deflected to the left in the Southern Hemisphere).

The Greenhouse Effect and Global Warming

Wed, 24 Feb 2010 00:01:44 +0000

The greenhouse effect contributes to global warming; however, the greenhouse effect is critical for life to exist on Earth. Today, there has been an increased greenhouse effect, which causes global climate to change, as well as other concerns and dangers.

Greenhouse Effect Animation

What is Earth’s energy balance?

Answer: The energy balance is a way of showing what happens to the energy (insolation) emitted by the sun. The Sun emits radiation (energy). Some of the radiation is absorbed by Earth at the surface (land and water), some of the radiation is absorbed in the atmosphere, and some of the radiation is reflected back out into space (by the atmosphere - clouds - and by the surface).
What is the greenhouse effect and how does it cause global warming?

Answer: The incoming energy has a short wavelength and is in the form of mostly visible light (as well as some ultra violet and infrared radiation). The energy from sun is absorbed by surface materials (such as plants, rocks, soil, water, etc.). This energy is transformed into heat, and is re-radiated by Earth as infrared radiation (which has a longer wavelength than visible light). Some of the infrared radiation escapes from Earth’s upper atmosphere into space. Some of the infrared radiation is trapped by compounds in the atmosphere. Some of the compounds that trap the radiation will re-radiate the energy back towards the surface, warming the Earth’s surface. The more compounds (or gases) in the atmosphere, the more radiation is trapped, the more radiation is re-radiated, and the more Earth is warmed.
What are some of the compounds that trap outgoing infrared radiation?

Answer: Some of the compounds that trap outgoing radiation include:

A. Carbon dioxide

B. Methane

C. Water vapor

D. Trace anthropogenic (human caused) gases include:

- Tropospheric ozone

- Chlorofluorocarbons

- Nitrous oxide

- Methane
What are some of the human activities that have increased the amount of greenhouse gases in the atmosphere?

Answer:

A. Burning of fossil fuels

B. Deforestation - the burning of trees

C. Factories

D. Production of cement

E. Agriculture

F. Landfills
What are some of the problems associated with global warming or global climate change?

Answer:

A. Rising sea levels - islands and low elevation areas can become covered with water and there will be an increase of erosion to costal areas

B. Increase in intensity and frequency of storm activity - ecosystems can be wiped out

C. Regional changes in climate - arid land areas will become drier and other areas will become wetter

D. Distribution of biomes will probably change - alpine tundra may be lost, and others will expand

E. Rising temperatures will cause:

- Polar ice caps will melt

- Coral reefs will be bleached and destroyed

- There will be more endangered species and some species will become extinct
What are some steps that I can take to reduce my impact on Earth?

Answer:

A. Become educated - the more you know, the better the decisions you will make

- Visit the EPA website on how you can reduce your impact of global climate change

B. Choose alternative transportation - walk, bike, and public transportation are good options - if you decide to drive, make sure that your car is tuned up

C. Choose energy efficient appliances

D. Replace old lightbulbs with energy efficient bulbs

E. Consider alternative energy options

F. Reduce your waste - turn off the lights when you leave the room and don’t leave the water running

G. Bring reusable bags with you when you go shopping

H. Use a reusable water bottle

Tsunamis

Sun, 28 Feb 2010 20:30:00 +0000

Tsunamis (also known as seismic sea waves and are commonly called tidal waves) are large waves often generated by earthquakes (tides do not influence or cause tsunamis).

Most tsunamis result from water that is displaced when there is movement along a fault located on the ocean floor. However, tsunamis are also triggered by large underwater landslides, underwater volcanic eruptions, and meteor impacts with the ocean.

Image from Wikipedia

Once a tsunami is generated, energy is moved at high speeds across the ocean. In the open ocean, a tsunami is only detected by sensitive measuring equipment because the wave height is usually less than 1 meter and the distance between wave crests is very great (ranging from 100 to 700 kilometers).

Image from Wikipedia

Once the tsunami enters shallower waters, the wave is slowed (by the seabed), and the wave begins to pile-up on itself, thus building in height. Most tsunamis do not exceed 30 meters (100 feet) in height. In addition, once a tsunami occurs, it typically consists of several large waves (a series of 7 or 8 waves are common).

What are the warning signs that a tsunami is approaching?

Answer:

A. Rapid withdrawal of water from the beaches

B. Animals moving to higher grounds (or observing that animals are behaving in a atypical fashion)

C. An earthquake

D. The Pacific Warning System (TWS) alarm goes off
What do I do if a tsunami occurs?

Answer:

A. Move to higher ground immediately!

B. Head inland - move far away from the coast
What can I do to prepare for a tsunami?

Answer:

A. Have an emergency disaster survival pack ready (include a first aid kit, radio, food, water, and clothing)

B. Have an evacuation plan in place - discuss evacuation options with family members and coworkers
Can a tsunami occur in New York?

Answer: Yes! However, it is not very likely. There is a much higher likelihood that a tsunami will occur in the Pacific Ocean because it is more tectonically active than the Atlantic Ocean. Earthquakes and volcanic eruptions are extremely common around the Ring of Fire. Although, there have been significant landslides off the west coast of Africa in the geologic past that have generated tsunamis, they are rare. Movement along the Caribbean Plate could cause a tsunami, and depending on the magnitude of an earthquake in the Pacific Ocean, and slight tsunami may be detected in New York.

Running Water: Surface Runoff, Streams, & Rivers

Sun, 28 Feb 2010 22:19:01 +0000

Refer to the diagram Relationship of Transported Particle Size to Water Velocity on page 6 of the Earth Science Reference Tables

Once rain or other forms of precipitation hits the Earth’s surface, it can either infiltrate (seep into the ground), evaporate, undergo transpiration (water vapor released by plants), or become runoff. All of those potential paths play an important role in the water cycle.

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Runoff is precipitation that does not infiltrate or evaporate. Factors that determine how much water flows across the surface include:

The amount of water present
The moisture of the soil
The soil texture
The slope of the land
The vegetation

Water can flow as a thin sheet (known as overland flow) across the surface and can cause sheet erosion.

Vegetation helps to slow and reduce sheet erosion. The plant roots help to keep the soil in place. This is especially important on steep slopes, where there is little time for the water to be absorbed into the ground. If there is a lack of vegetation, a gully can form, and if erosion continues, a gulch can form.

A gully is a small ditch or funnel created by overland flow as the runoff moves downhill.

A gulch a deep V-shaped valley.

Eventually, the runoff will reach a stream or a river. The stream’s velocity will determine how the stream will flow and the size of sediment that is being transported. The diagram Relationship of Transported Particle Size to Water Velocity on page 6 of the Earth Science Reference Tables, shows how stream velocity affects the carrying capacity; as the velocity increases, the stream is able to transport larger sediment. Additionally, as the velocity decreases, the largest sediment will be deposited first.

How does water flow in a stream?

Answer:

A. Laminar Flow: Water particles flow in a straight line parallel to the stream channel (defined stream path). There is very little mixing of water particles.

B. Turbulent Flow: Water moves in a random fashion; water swirls, whirlpools are created, and water particles are mixed.
How does a stream transport sediment?

Answer: A river transports its sediment, also known as “load”, in several ways, see below:

A. In Solution: Also referred to as the dissolved load. Water dissolves the bedrock over time, dissolving sediments and minerals into the water, which is transported in this load. The velocity does not effect the stream’s ability to carry particles within the dissolved load. Once the minerals are in solution, they remain in solution until they are precipitated out.

B. In Suspension: Also referred to as the suspended load. This load consists of the small sediment particles (fine sand, silt, and clay). The stream’s velocity does effect the amount of material carried in this load.

C. Bed Load: Larger sediments are moved along the bottom of the stream channel by rolling, sliding, and saltation (jumping or bouncing). The bed load is the main contributor to downcutting (the downward weathering and erosion of a stream into its channel).
How does a stream or river erode?

Answer: The water velocity will determine the size of the sediment transported (refer to the diagram Relationship of Transported Particle Size to Water Velocity on page 6 of the Earth Science Reference Tables). The diagram indicates that as water velocity increases, the water is able to transport larger sediment. For example, in order for boulders to continue to be moved in the stream or river, the water must be moving at a velocity of at least 200 cm/s.

The transported sediment will weather (wear away and break down) the surfaces that they flow over. The stream’s channel will become deeper as the sediments carve deeper into the stream channel. (Recall, that this process where the stream channel is made deeper, is known as downcutting). As the sediments collide, pieces of the sediment are broken off and larger sediments create smaller sediments. The sediments continue to rub and grind against the surrounding rock. This process where rocks are worn away by the crushing and grinding of other sediments, is known as abrasion. As the rock is worn away, the resulting rock is rounded and smooth.

The weakest rocks and sediments are eroded first. Waterfalls are created during this process. The water continues to flow over the the hard, resistant bedrock, and erodes the soft, non-resistant rock.

Volcanic Eruptions: Environmental Impact and Hazards

Tue, 20 Apr 2010 19:57:41 +0000

Refer to the Tectonic Plates diagram on page 5 and the Selected Properties of Earth’s Atmosphere diagram on page 14 of the Earth Science Reference Tables

Volcanic eruptions are extremely common along plate boundaries. However, since New York is not located along a plate boundary, we tend to only hear about the large and destructive eruptions. In April 2010, Iceland’s Eyjafjallajokull volcano erupted explosively and spewed out huge amounts of lava, rock, ash, and harmful gases into the atmosphere.

What are some of the gases that are released into the atmosphere during a volcanic eruption?

Answer: The main gases that are released during an eruption include water vapor, carbon dioxide, and sulfur dioxide.
What are some of the effects of the volcanic gases?

Answer:

A. Water vapor and carbon dioxide are greenhouse gases and they contribute to global warming.

B. Sulfur dioxide remains in the atmosphere and is eventually converted to sulfuric acid. If the tiny droplets of sulfur dioxide reach the stratosphere, they can reflect some of the sun’s radiation, and can cool Earth for approximately 1-4 years (depending on the amount and how widespread). Acid rain results when the sulfur dioxide is washed from the atmosphere, Sulfur dioxide can accelerate ozone destruction, and when it combines with sunlight, dust, and oxygen, it will result in smog (or vog - volcanic smog).

Sulfur dioxide can also cause health problems. Such health problems include irritation to the skin, eyes, and nose, can affect respiration.
What are other problems associated with volcanic eruptions?

Answer: Depending on the size of the volcanic eruption, people living near the volcano can be forced to evacuate their home either temporarily or permanently. Lahars, tephra, flooding, and pyroclastic flows can destroy crops, plants, electrical grids, towns and cities.

Watch the video to learn more about the environmental impacts and hazards of volcanic eruptions.

Acid Rain

Tue, 20 Apr 2010 23:08:38 +0000

Although all rainfall is slightly acidic, precipitation that has a lower pH than normal rainfall (lower than 5.6), can be extremely harmful. Acid rainfall includes both wet precipitation (rain, snow, and fog), and dry depositions (particulate matter). The depositions occur downwind of volcanoes and downwind of where there is burning of fossil fuels and sulfur dioxide and nitrogen oxides are emitted.

What gases are the main contributors to acid rain and acid deposition?

Answer: Sulfur dioxide, nitrogen oxides, and other gases released from coal-fired power plants.
How long has acid rain been an environmental problem?

Answer: Acid rain has been a problem since at least the Industrial Revolution. However, it is a global environmental concern today, and affects the majority of countries.
How do the gases become acids?

Answer: In the atmosphere, sulfur dioxide and the nitrogen oxides undergo reactions with oxygen and water vapor, and become acids.
Where is acid rain a problem?

Answer: The acids will travel with the prevailing winds and will eventually be deposited as acid precipitation or dry deposition. Depending on the source emitting the acids and how high the particles travel in the atmosphere, will determine where the acids are deposited (locally or regionally).
How does acid rain affect ecosystems?

Answer:

A. Soils may lose their fertility after being exposed to acid rain, because nutrients are removed as the water passes through the soil particles or the acid releases elements that are toxic to the plans.

B. Acid rain causes trees and plants to become more susceptible to disease and drought, and are weakened and eventually die.

C. A loss of vegetation causes a change in temperature and water content to the soil, affecting the other organisms that grow. There is less habitat and food for animals.

D. Lakes become more acidic, causing the plants and marine organisms to die.

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Geocentric Science

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