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Wind can power storms, make electricity, and carve rock. It can also whip up some wild fun.

Wind is air on the move. Have you ever watched a windsurfer? The wind blows the sail, and the rider takes off! Did you ever fly kite? If so, you have seen wind at work. What causes this wind to blow? What can it do? Let's find out.

Wind is just moving air. It starts with the sun. The sun warms up land and water. The air above them warms up, too. As air warms, it rises and leaves an open place. Cooler air rushes in to fill it. That rush is called wind.

Have you noticed that beaches are often windy? Air is always rushing between water and land. That's because land heats up faster than water. It cools down faster, too. So wind races to the warmer spot.

Some winds always blow certain ways. Other winds are sudden. Mountains, islands, and even buildings can change how wind moves.

You cannot see wind. Yet you can see what is does. Have you seen a tree swaying back and forth? Have you seen someone's umbrella blow away?

Wind can even chip into rock. It blows away tiny pieces of rock. Slowly, it carves the rock into a new shape. Wind can change land bit by bit. Wind can even wear down mountains if it has time. This is called erosion.

Winds have long helped people get places. People sailed the Pacific Ocean as early as 3,000 years ago. Some of the winds there always blow the same way. Early sailors knew this and used winds to plan their trips.

Famous winds blow around the middle of Earth. Ships used these winds to sail around the world. The winds became known as trade winds. Now, people who sail boats do it mostly for sport. Yet even today's sailboats depend on the same wind patterns as sailboats from long ago.

Wind can even make electricity. Do you know what a wind farm is? Wind farms do not grow corn or wheat. Instead of crops, wind farms have wind turbines. They are giant windmills. Each one is taller than a 20-story building. Wind spins these turbines. That turning runs machines. The machines make electricity.

The United States powers about 4.5 million homes with wind power. Wind farms produce power without making air, land, or water dirty. That's not all. We'll never run out of wind!

Wind is not always helpful. Sometimes during a storm, air above ground moves faster than air on the ground. The air in between ends up rolling into a tube. Have you rolled clay? It is kind of like that. Then, if warm air rises in the storm, look out! It can turn the spinning wind so it stands up. The spinning storm becomes a tornado.

Most tornadoes last just a few minutes. Yet the winds can lift cars and houses. Tornadoes go hundreds of kilometers an hour.

Hurricanes spin like tornadoes. They are much larger, though. Hurricanes form over warm oceans. Warm, wet air rises. Air moves in underneath. Then that air rises, too. As Earth spins, it makes these wet clouds spin. When winds reach 119 kilometers (74 miles) an hour, these storms are hurricanes.

Hurricanes blow away trees and buildings. They can cause waves that flood coasts. Hurricane Katrina hit New Orleans, Louisiana, in 2005. Many people died or lost their houses.

We live in a windy world. Wind helps fly kites. Yet it tears into mountains and houses, too. Wind carried explorers to new places. Now it lights homes. It helps keep us sailing on.

Article by Beth Geiger. Top-of-page photograph by T. J. Florian/Rainbow/agefotostock.com. "Wind at Work" appears on page 18 of the September 2008 issue.