Tuesday, June 6, 2017

Why the wind calms once the sun sets

Jaci Drazen Zons posted, "I have a question. Why does the wind seem to die down at nighttime? Always seems like there's a nice breeze then come nighttime and it's gone!"  That's a very good question, Jaci!

Let's think of our atmosphere like a pot of water on the stove.  Once you turn the stove on, the water begins to boil.  The longer the pot is on the stove, the hotter the water gets and the stronger the boil.  Once the stove is turned off, the water slowly begins to cool and the boil comes to an end.  The air movement in our atmosphere acts very similar to the water in the pot on the stove.

As the sun heats the surface of the earth, air begins to rise and 'mixes' with the air aloft.  This mixing allows stronger winds that typically occur above the surface of the earth to mix down to the surface, causing a gusty afternoon breeze.  As the sun sets, the surface of the Earth cools much more rapidly than the air above.  The cooler and more dense air at the surface doesn't have an opportunity to mix with the air aloft, causing wind speeds to decrease.  As the sun rises the next day, the cycle begins all over again.

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