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

Have you ever tried windsurfing? It's like surfing, but with a sail attached to your surfboard. Feel the salt air hit your face. Wait for the wind to pick up. Then hang on! The next thing you know, you are tearing across the cool water.

You may not have windsurfed before. Maybe you've flown a kite on a spring day. Perhaps you've sailed in a sailboat. People have used wind in different ways for thousands of years.

What is wind? What causes it? Wind is just air on the move. The sun causes it. When the sun shines on land or water, the land or water warms up. So does the air above it. As air warms up, it becomes lighter. It rises. Cooler air rushes in to fill the gap. That rush is wind.

Earth swirls with wind all the time because its surface heats unevenly. Water, for example, takes longer to heat and cool than land. So air is always rushing between water and land. Now you know why beaches are so breezy!

Different types of places, such as forests, deserts, and prairies, also soak up heat from the sun differently. They cool down at different rates, too. Don't forget about the cold places at Earth's top and bottom and the warm area around the planet's middle. Air moves constantly between all these hot and cold spots.

Some winds blow in regular patterns across thousands of miles. Other winds are local and sudden, such as gusts in a thunderstorm. Mountains, islands, and even tall buildings affect how wind moves. No wonder wind comes in so many varieties. Gales and gusts, breezes and puffs are just a few kinds of wind.

You can't see wind. Yet you can see its handiwork. Have you seen a tree branch swaying? Wind. Ever watch an umbrella blow inside out? Wind again.

Wind does more than just toy with umbrellas. It sculpts rocks and landscapes by tearing away tiny pieces off rocks. All those pieces add up. Piece by tiny piece, wind can erase a whole mountain. This process of wearing away is called erosion. Bit by bit, over millions of years, wind carves rock into cool new shapes. What about all those loose pieces? Wind piles them into graceful sand dunes. Not bad for an invisible force.

Long before people used wind to have fun at the beach, they used wind to get places. Ancient Egyptians hoisted sails to travel up and down the Nile River. The Polynesians set sail across the Pacific Ocean at least 3,000 years ago. Wind blew the Vikings on their famous raids.

These early sailors were smart. They noticed that Earth's major winds blew in predictable patterns. Studying these patterns helped sailors plan their voyages.

Some of Earth's most reliable winds blow west near the Equator. That's the imaginary line around the planet's middle. Trading ships hopped on them to send goods around the world. These helpful winds are called trade winds. You could call trade winds the original fast lanes.

People still sail boats today. Modern sailing, however, is mostly for sport. Even so, today's sailors still depend on the same wind patterns that pushed trade ships hundreds of years ago.

To cross the ocean, people don't need wind anymore. They have airplanes for that. Still, wind can help us in other ways. One way is by making electricity.

The Horse Hollow wind farm in Texas grows no wheat or corn. Instead, it has hundreds of steel wind turbines. Each tower is taller than a 20-story building. Hear that weird hum? That's the blades spinning in the steady wind.

Wind, after all, is energy. It's clean and renewable energy, too. Wind makes the turbines spin. The spinning turns a generator. Then the generator makes electricity.

Wind farms work best in open places where nothing gets in the wind's way. So far, the United States snags enough breeze to power about 4.5 million homes. That's only about one percent of the electricity we need. Slowly, though, the role of wind power is growing. More wind farms seem to crop up every year.

Wind isn't always fun or helpful. It can also be terrifying. Just ask anyone who has seen a tornado. It is a vertical column of spinning air. Tornadoes form in severe thunderstorms. They can start when wind above the ground moves faster than wind at ground level. The air in between rolls into a spinning tube.

Sometimes air rising inside a thunderstorm tilts the spinning tube upright. Then watch out! It's tornado time. Most tornadoes only last a few minutes. Yet their violent winds do loads of damage. Tornadoes can blast to pieces cars, houses, and anything else in their way.

On May 3, 1999, a string of deadly tornadoes ripped across Oklahoma. Weather scientists followed one of the twisters in a truck. Using radar, the scientists clocked the tornado's winds at 484 kilometers (301 miles) an hour. It was the fastest tornado ever recorded.

Tornadoes may be terrifying, but hurricanes are huge. These massive storms easily stretch across three states. Hurricane winds pack a major punch. Hurricanes form over tropical oceans. Warm, moist air rises. More air moves in underneath. Then that air rises, too. Big, wet clouds start to gather.

Over a few days, Earth's rotation causes the growing mass of clouds to spin. When winds reach 119 kilometers (74 miles) an hour, the storm becomes a hurricane. Winds in the strongest hurricanes race at over 249 kilometers (155 miles) an hour.

Once hurricanes hit land, they can do some extreme damage. The winds blow away trees and buildings. Towering waves flood coasts. In 2005, Hurricane Katrina plowed into New Orleans, Louisiana. Water flooded the city. Thousands of homes and lives were lost.

From gentle breezes to strong gusts, wind is everywhere. It can sculpt mountains and tear apart houses. Long ago, wind carried explorers to new places. Now it helps light cities and makes sports like windsurfing a thrill. The next time you are just shooting the breeze, think about the many ways that wind changes our world.

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.