The wind is air in motion. Moving anything requires a force. Violent destructive winds, as well as gentle summer breezes, result from a complex interplay of different forces. One of these forces results from a pressure gradient, or how fast pressure changes over distance. Strong winds almost always result from large pressure gradients. Recently, southern Wisconsin has been under the influence of a weather pattern that has strong pressure gradients, and thus strong winds.
Near the Earth’s surface, the friction plays a pivotal role in wind, acting to slow the wind. Over the open lakes the wind will be faster than through a stand of trees, where it will be slowed by friction. In the presence of buildings, the air can be funneled between buildings and pick up speed.
The air flows from high atmospheric pressures to low pressures. The Coriolis force pulls the wind to the right so that winds blow counterclockwise around lows and clockwise around highs in the Northern Hemisphere. Friction slows down the wind and weakens the Coriolis force. So, if you stand with your back to the wind, and then turn about 30 percent to your right, low pressure will be on your left-hand side
Thunderstorms also can cause strong winds. Thunderstorms have upward air motions, called updrafts. There are also downdrafts, or sinking air in a storm. Such downdrafts carry air from high elevations in the atmosphere rapidly to the ground. Since wind speed is nearly always much larger at high elevations, the downdrafts carry very high-velocity air to the surface creating the winds of more than 100 mph.
