Category Archives: Phenomena

How do snowflakes grow?

Posted on December 26, 2011 by Weather Guys Editor

A snowflake can be an individual ice crystal or an aggregate of ice crystals. Ice crystals can grow by water vapor deposition on the crystal or by collisions with other cloud particles.

An ice crystal can grow if the air around it has a relative humidity near 100 percent. The ice particle grows by water vapor deposition. Growth by deposition is generally slow. If you find nicely shaped snowflakes, they likely were produced by vapor deposition. Continue reading →

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Why does the moon look red during a lunar eclipse?

Posted on December 12, 2011 by Weather Guys Editor

A total lunar eclipse could be seen in cloud-free regions across most of the United States and Canada on Saturday morning, Dec. 10. In a total lunar eclipse the sun, Earth and moon line up and the Earth casts its shadow on the moon. The moon is always a full moon and it never goes completely dark during a total lunar eclipse. It appears reddish for the same reason that sunsets and sunrises often have a red tint. Continue reading →

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Why was it so windy last week?

Posted on October 24, 2011 by Weather Guys Editor

The wind is air in motion. Moving anything requires a force. Violent destructive winds, as well as gentle summer breezes, result from a complex interplay of different forces. One of these forces results from a pressure gradient, or how fast pressure changes over distance. Strong winds almost always result from large pressure gradients. Recently, southern Wisconsin has been under the influence of a weather pattern that has strong pressure gradients, and thus strong winds. Continue reading →

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What is the status of the ozone hole?

Posted on October 17, 2011 by Weather Guys Editor

The winter atmosphere above Antarctica is very cold. The cold temperatures result in a temperature gradient between the South Pole and the Southern Hemisphere middle latitudes. Continue reading →

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Why are Some Clouds Whiter than Others?

Posted on August 29, 2011 by Weather Guys Editor

Clouds are made of small water drops and small ice crystals that scatter light from the sun in all directions. These individual drops and crystals are clear. It is the multitude of drops . . . Continue reading →

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