Tag Archives: Phenomena

Why are the cloud streamers behind jets different sizes?

The white condensation trails left behind jet aircraft are called contrails (condensation trails). Contrails usually form higher than 26,000 feet above the ground. Contrails form when hot, humid air from jet exhaust mixes with surrounding air of low water vapor content and low temperature. The clouds that form are similar to the cloud you see when you exhale in cold air and “see your breath.” Continue reading

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Why does it smell good after a rain?

Many times after a rain, there is a distinctive odor in the air — a sort of musky smell. This pleasant fragrance is most common in rains that follow a dry spell. If you are a gardener, you may find this smell similar to the smell you sense when you turn over your soil. Good organic soils contain bacteria. One bacterium that is abundant in damp warm soils is actinomycete. Continue reading

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How do large snowflakes form?

There are four basic shapes of ice crystals: the hexagonal plate, the needle, the column and the dendrite. The dendrites are hexagonal with elongated branches, or fingers, of ice; they most closely resemble what we think of as snowflakes. The temperature at which the crystal grows determines the particular shape. A snowflake is an individual ice crystal or an aggregate of ice crystals. Large snowflakes are aggregates of ice crystals. Continue reading

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What causes wind gusts?

A wind gust is a sudden, brief increase in the speed of the wind followed by a lull. According to National Weather Service observing practice, gusts are reported when the peak wind speed reaches at least 18 mph and the variation in wind speed between the peaks and lulls is at least about 10 mph. The strongest wind gust recorded occurred at Australia’s Barrow Island, with a gust of 253 mph that occurred during tropical cyclone Olivia on April 10, 1996. Continue reading

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What were the top Wisconsin Weather Events for 2011?

Each season in 2011 had a memorable weather event, some with negative impacts. There were two good snow storms in February. The Groundhog Day blizzard had wind gusts of up to 60 mph and snowfall depths ranging from 1 to 2 feet. That resulted in snow drifts of 6 to 10 feet. The second storm occurred on February 20-21 with snow accumulations between 8 and 15 inches. Freezing rain and sleet also fell across southern Wisconsin. Continue reading

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