First Warning Weather University: Why Does Wind Blow?


AUSTIN (KXAN) –  What is wind and how does it work? Wind is defined as the movement of air. In the natural world, it’s caused by differences in “pressure.” “Atmospheric pressure” is the weight of the atmosphere above us constantly squishing down on the earth.

On a typical day, the weight of the atmosphere exerts a pressure of about 14.7 pounds per square inch.

The grass in your front yard, the water in the lakes, and even our bodies are constantly under that pressure. We’re accustomed to it, so it just feels normal.

When a storm blows in, rising air inside of that storm lifts some of that weight off you, hence, the pressure drops.

On a bright, sunny day, there is actually air sinking down upon us, so the atmosphere seems to weigh a bit more.

Let’s look at a small-scale example of this:

Say we have a storm downtown, but the sun is out over Lake Travis. This means there’s a little “low pressure” system over the city, and a “high pressure” system over the lake. Air always blows from high to low pressure — it’s the same principle that allows airplane wings to generate lift.

In our example, this means wind would be blowing eastward, and the bigger the difference in pressure, the stronger the wind.

Here’s the complicating factor: on a rotating planet, the “Coriolis Force” comes into play, which adds a spin into the mix.

As the air is going from high to low over Austin, it’s deflected rightward since we’re in the Northern Hemisphere. The air ends up spiraling inward to the low-pressure center. Ultimately, that is what gives you counter-clockwise rotating storms.

The earth is always trying to reach equilibrium, evening out the pressure everywhere. It’s never quite able to, so the winds will always blow.

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