Why is this place so windy? It seems that Mount Washington sits at a perfect storm location at the convergence of three major storm tracks. Plus, its prominence with the surrounding landscape amplifies the winds with a funnel effect.
If you can’t go there, pay attention to the next thunderstorm. Thunderstorms are wind machines. Here is animated air motion made darkly visible. They’re even easy to understand. You start with a hot August day, the Sun heating the ground, which warms the air just above it. Warm air rises, so up goes a gas bubble like a hot air balloon.
Temperature normally falls rapidly with altitude. But if the day is humid, the rising air package remains “lighter” than the air around it, so it keeps going up. Eventually it cools to its dewpoint and can no longer hold its moisture, which suddenly condenses into billions of droplets. A cloud is born.
Hot air from below keeps rising to feed this cloud. Meanwhile, its droplets rub together to create static electrical charges. At the same time, since you can’t have a vacuum on the ground below, surrounding air is pulled in. The air pageant is now getting more animated. When rain starts forming and falling, cooling the air within the cloud, this denser cold air plummets, intertwined with the rain.
Now you have scary-strong winds. Some warm air is still rising into this “mature” thunderstorm, while adjacent streams of cool air are plunging down from it. Even in a moderate storm, the downdrafts register 22 miles per hour to match the speed of the surrounding downpour. The downburst now hits the ground and, unlike the liquid rain, spreads radially outward in all directions, bending trees horizontally and inverting umbrellas.
So what causes wind? Differences in air temperature. Simple, really – and fun to observe.
