Living in the Plains, we Nebraskans and Iowans are no stranger to the wind. We’ve got a strong love/hate relationship with it, too. In the winter, we say, “It wouldn’t be so bad, if it wasn’t for this wind” when it’s 20° but the wind chill is below zero. In the summer, we say, “If only there was a slight breeze” when it’s 95° but feels more like 105 degrees instead. We’ve dealt with calm winds and 80 mph wind gusts (excluding tornado winds here), but gosh darn it, what causes all of this wind?!
Well, like most parts of weather, it’s a few things all combined. The easy answer though, is wind is caused by a difference in atmospheric pressure. Some of the pieces going into the changes in pressure are temperature variations across areas (via heating from the Sun) and the Earth’s rotation. In fact, maybe you’ve heard of this rotation. In the Northern Hemisphere, the Coriolis force causes our wind to curve to the right (it curves to the left in the Southern Hemisphere). [*Side note: Coriolis force does not cause toilet water in the Southern Hemisphere to spin opposite from toilet water in the Northern Hemisphere when flushed, despite what you may have heard. Coriolis force impacts on a BIG scale, and toilets flushing is a small scale.]
Anyway, back to the wind! (Which, we’ve been talking about this whole time, but we got a little side-tracked along the way. It happens when it’s the blogger’s “Friday”.) So, how can we “see” these differences in atmospheric pressure when we can’t even see the wind? Thankfully, science has a lot of cool ways to measure these invisible forces, one of these tools is a barometer, which measures changes in pressure. Once we have measurements of the pressure, it can be plotted on a map. Then, lines are drawn between points of equal pressure and these lines are called isobars. In this example, the isobars are the white lines on the map below.
When the isobars are close together, the gradient between higher and lower pressure is greater, which means the wind will be stronger. We know this because the Earth wants to reach equilibrium, so air moves from areas of higher pressure to lower pressure in an attempt to equal it all out. Thus, creating WIND! Boom, science.