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Where does wind come from?

 Kei Uesugi/Getty Images
Kei Uesugi/Getty Images

Spring is unfolding here in the South, ushered in by dramatic whooshes of wind. Which reminded me of last spring, when on a particularly gusty day my then 3-year-old daughter asked, "Who keeps turning the wind on?"

Turns out the answer is fairly poetic: Wind is merely air in motion. And to look for its source is to look at another muse of the poets, the sun. After all, the sun warms the Earth each day, with some parts of the world catching more rays than other parts. The equator soaks up a lot of the sun; while outliers, like the poles, net the least amount of sunlight.

This results in differences in air pressure. When air is warmed, it rises -- its molecules are less closely packed together. And when it rises it's replaced by cooler air, which is lower in pressure, or more densely packed together. Behold, a wind is born.

What makes wind blow at different speeds? The greater the difference in pressure, the greater in airflow to replace displaced wind. Also, the shorter the distance between the two areas of pressure, the more wind is created. And wind traveling over vast and empty distances (like a desert or ocean) produces bigger blasts.

Think of the Earth as a terrarium, with the atmosphere represented by the glass enclosure, containing warm and cool air, forever trading places and mixing to create unique compositions of air molecules. One day a gentle breeze, the next day a gale ...

More reading: How Weather Works by Robert Lamb

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