Weather Whys; Friction

This is weather-wise. When a person briskly rubs his hands together, he can feel the effects of friction, which takes the kinetic energy in the movement of the hands and converts it into heat. Friction is defined as resistance to the motion of two objects, which are in contact with one another. The resistance occurs because the surfaces of one or both of the substances are rough. If you run your hand across a freshly cut block of wood, you can easily feel that roughness. But on a smooth metal plate, you can't, because the size of the rough bits on the surface is too small. Friction is an important part of daily life, as one can easily imagine. In fact, it's importance becomes painfully clear when someone tries to walk on a patch of ice, which is relatively frictionless. But friction is also an important factor in the atmosphere, because the ground isn't a smooth uniform surface, the wind blowing across it experiences some resistance. Winds are also affected by the Coriolis force, which is a result of the Earth's rotation.

It makes the wind veer to the right in the northern hemisphere. But the slower the winds, the less effect Coriolis has on. And since friction slows the wind down, it lessens the effect of the rotational force, keeping the wind from turning too much to the right. While that may seem somewhat trivial, it's actually of great importance to the way the weather works. After all, friction is what makes wind spiral into centers of low pressure and away from centers of high pressure instead of just going in circles. That means storms and other weather features can grow, change, and dissipate. You might call it full employment for meteorologists. Weather wise is produced with the assistance of the National Weather Service Warcast Office and the National Severe Storms Laboratory, both in Norman, Oklahoma, and is made possible through a grant from the National Science Foundation. For Weather wise, I'm Drew Barlow.