Q: Some days it's very breezy, and other days, there seems to be no wind at all.

What causes wind?

A: There are several reasons why it's windy one day and calm the next, says

Brent McRoberts of Texas A&M University. Wind is caused by air flowing from an

area of high pressure to an area of low pressure, he explains. "Add to that the

rotation of the Earth," he adds. "The Earth's rotation also affects air flow.

And during daylight hours, the heat from the ground causes a convective reaction

to occur, meaning heat is moving away from the Earth's surface and sunlight

causes an excess of energy buildup. At night, the convection is much less,

meaning winds die down. Nature is always trying to balance things out, and the

result of trying to balance and equalize pressure from one area to another

results in wind."

Q: Are there different kinds of wind?

A: Winds that blow uphill are called upslope winds, and winds that blow downhill

are called downslope winds, McRoberts adds. "Winds that blow from large bodies

of water inland are called sea breezes. Santa Ana winds are dry winds that can

fan forest fires, especially in California. The U.S. has some of the windiest

weather on Earth. In fact, the highest wind speed ever recorded in the U.S.

occurred April 12, 1934, on Mount Washington, N.H. For a few seconds, the wind

blew an incredible 231 miles per hour."

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Weather Whys is a service of the Department of Atmospheric Sciences at Texas

A&M University.

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