Weather Whys – Why does the wind seem to die down at...

Weather Whys – Why does the wind seem to die down at night?

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TexasUniv_NewLogoQ:  Why does the wind seem to die down at night?

A:  The simple and quick answer is that there’s no sun, says Brent McRoberts of Texas A&M University.  “Wind is a form of energy and it gets much of its strength from the sun,” he explains.  “You can think of wind as a huge river of air over land, and it does this day or night.  But as the sun rises and starts heating up the ground, rising warm air mixes with slower air near the ground and with air moving faster that is above ground.  This faster-moving air is pushing downward, and it creates windy and breezy conditions as the day progresses.”

Q: So what happens at night?

A:  When the sun starts to set, this mixing of conditions doesn’t happen as much, so the winds start to slow and eventually die down.  “Remember that hot or warmer air expands and rises,” McRoberts adds.  “At night, the ground begins to cool.  Air closer to the ground cools by radiation, so there is a lack of heat and energy and these directly affect air currents. So the winds at night and in the early morning hours are usually the weakest.  But remember that cold fronts and storms can occur and these directly affect wind speed, too.”