A blizzard, according to Wikipedia, is “a severe storm condition characterized by strong winds and reduced visibility. By definition, the difference between blizzard and a snowstorm is the strength of the wind. To be a blizzard, a snow storm must have winds in excess of 56 km/h (35 mph) with blowing or drifting snow which reduces visibility to 400 meters or ¼ mile or less and must last for a prolonged period of time — typically three hours or more.”

Last night certainly counted as a blizzard. As the people who experienced 25 foot waves crashing on the shores of Lake Michigan in Chicago. Or the literally thousands of motorists stranded on the roads. This was one of the worst blizzards in history, and the full impact is yet to be realized.

Weather, according to Wikipedia, “is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy.” Seems pretty basic when you look at it like that! Most weather tends to occur in the troposphere, which is the layer of the atmosphere that we live in. Wikipedia goes on to say that “weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods of time.” And, unless you’re being specific, the term generally applies to weather on Earth.

Weather basically occurs because of density differences in temperature and moisture between different points on the earth. These differences are generally caused by the varying sun angles at any point on the earth, which varies by latitude from the tropics. The strong temperature differences between the tropics and the poles is what causes the jet stream, which is a fast flowing, narrow air current. Weather systems in the mid-latitudes, like the United States and much of Europe, is caused by instabilities of the jet stream flow. Sometimes the jet stream dips down from the poles, bringing with it cold air. Sometimes it causes a ridge that brings up warm, moist air from the tropics. All this combines to create the weather systems that get reported on each day.

Weather on Earth is complex and chaotic!

On Earth, “common weather phenomena include wind, cloud, rain, snow, fog and dust storms.” Less common events include “tornadoes, hurricanes, typhoons and ice storms.” Wind is created by differences in air pressure levels on the planet, with air flowing from regions of high pressure to low pressure. Pressure itself is caused by varying temperatures on the planet, with colder temps producing lower air pressure, and higher temps associated with high pressure systems.

The atmosphere is a hugely complex and chaotic system, where changes to one variable (temperature, pressure, moisture) can have huge effects on the weather in a particular location, or a location remote from where the variable has changed. The dynamics of weather in many cases are poorly understood, which is why long term weather forecasts are so difficult to create. As the years go by and we are able to gather more data about actual weather events, our understanding of weather and climate increase, and that leads to an increased ability to make accurate forecasts. But the weather will always surprise us, and we should be prepared for anything at any time. If you tend to venture outside your home, you should take time to understand what weather events might be headed your way!

Essentially, a Glory is “one or more sequences of faintly colored rings of light that can be seen by an observer around his own shadow cast on a water cloud (a cloud consisting mainly of small, uniform sized water droplets). It can also be seen on fog and exceptionally on dew.”  The glory can only be seen when the observer is directly between the sun and cloud of refracting water droplets.

Solar glory at hot springs

Glories are not completely understood. The colored rings of the glory are caused by two-ray interference between “short” and “long” path surface waves – which are generated by light rays entering the droplets at diametrically opposite points (both rays suffer one internal reflection). Glories are often seen in association with a Brocken spectre, the apparently enormously magnified shadow of an observer, cast (when the Sun is low) upon the upper surfaces of clouds that are below the mountain upon which he or she stands. The name derives from the Brocken, the tallest peak of the Harz mountain range in Germany. Because the peak is above the cloud level, and the area is frequently misty, the condition of a shadow cast onto a cloud layer is relatively favored. The appearance of giant shadows that seemed to move by themselves due to the movement of the cloud layer (this movement is another part of the definition of the Brocken Spectre), and which were surrounded by optical glory halos, may have contributed to the reputation the Harz mountains hold as a refuge for witches and evil spirits.

The next time you have your back to the sun and clouds at your front, or are up high with clouds below, try and find a Glory on your shadow. If you have a camera with you, and see a Glory, send us a snapshot!

Source : Wikipedia

According to Wikipedia, a Nor’easter is “is a type of macro-scale storm along the East Coast of the United States and Atlantic Canada, so named because the storm travels to the northeast from the south and the winds come from the northeast, especially in the coastal areas of the Northeastern United States and Atlantic Canada.”

Specifically, a Nor’easter describes a low pressure area who’s center of rotation is just off the East Coast and who’s leading winds in the left forward quadrant rotate onto land from the northeast. Nor’easters can cause coastal flooding, coastal erosion, hurricane force winds and heavy snow. While they can occur at any time of the year, they are most frequent in the winter months. These systems are known for bringing down extremely cold arctic air from the north.

Satellite image of the intense nor'easter responsible for the North American blizzard of 2006. Note the hurricane-like eye at the center.

Nor’easters generally affect the United States, from Virginia to the New England cost, as well as Quebec and Atlantic Canada. They tend to bring massive amounts of precipitation, high winds, large waves, and marginal storm surges to coastal areas. In general, though, people tend to call any strong rain or snow storm in the Northeast a Nor’easter. The very name brings feelings of dread and anticipation to people in the region!

For more information, visit this Wikipedia article on Nor’easters.

Winter Storm Advisory: An advisory is issued by the National Weather Service (NWS) when a significant winter storm or hazardous winter weather is occurring, imminent, and is an inconvenience. This means bad weather is happening right now or will happen soon, but it won’t be as bad as what you get with a Winter Storm Warning.

Winter Storm Watch: A watch is issued when significant winter weather, like heavy snow, sleet, significant freezing rain, or a combination of events, is expected, but not imminent. A warning provides about 12 to 36 hours notice of the possibility of severe winter weather.

Winter Storm Warning: This is issued when significant winter weather is occurring, imminent, or likely, and is a threat to life or property. If you hear a Winter Storm Warning for your area, you should probably remain inside with a nice cup of hot chocolate! But be prepared to dig yourself out later!

During the course of any given winter, you are likely to hear all three of these weather statements issued at one time or another. Even here in Arizona, we get Winter Storm Warnings when the occasional super heavy snowstorm rolls through. It’s good to have a basic understanding of the urgency associated with each of these weather statements, as it ultimately helps you get prepared for the weather ahead. Keep an eye on the TV, or an ear to the radio, and always know what’s happening outside!

Sources : The Weather Channel