Why Does Weather Move West-To-East?

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By By Steve Pool

SEATTLE - You might think since the Earth rotates toward the east, that our weather would come from the east as we "run into" it. But no, our atmosphere is spinning along with us at nearly the same speed near the ground.

Instead, weather moves west-to-east thanks to the jet stream, which is a high-altitude wind that moves west-to-east and generally steers our weather.

It’s caused from the temperature difference between our warm equator and cold poles. High pressure at the warm tropics wants to flow toward the low pressure at the cold poles, but the Earth's spin deflects these winds to the east so that they make a circle around the globe (in both hemispheres) moving west to east at mid-latitudes.

The jet will dip to the north and south as individual low and high pressure systems form, but always carries our weather east.

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