Blowing in the Wind
Long before people knew how to use steam, gas, or electricity for power, they used the wind. Today people use sailboats mostly for pleasure, but ancient seafaring people relied on the wind in their sails to carry them all over the world.
Hot air is lighter than cold air. If you put hot air in a balloon, it rises—and that's how hot-air balloonists float high in the sky. Birds like eagles and hawks soar high above the ground, too. They spread their great wings to catch warm air currents and rise in lazy circles above us. Airplanes called gliders are lifted high in the air in much the same way.
The seaside is a perfect place for flying kites, because the wind almost never stops blowing. The sand on the beach warms up faster than the ocean does. As the warm air over the land rises, cool winds blow in from the sea. The beach is a good place to try hang gliding, too—which is about as close to being a human kite as you can get!
Everyone has seen trees tossing in the wind. But the wind isn't just scattering leaves for you to rake as it passes through. It's also helping the trees—and bushes and grasses and flowers—scatter their seeds. Wind carries all kinds of seeds to new places, where they can take root and grow. Maple seeds, dandelions, and tumbleweeds are just a few of the plants that rely on the wind to help them spread their seeds.
All around us the wind is at work. It brings changes in the weather. It carries birds and airplanes and boats and seeds to the four corners of the world. And sometimes, wind just helps people have fun! With the wind in your sail, you can go almost anywhere—on water, on ice, on land, in the air.
The wind touches us all every day of our lives. Everywhere you look, things are blowing in the wind!
- Is wind a push force or a pull force?
[anno: Wind is a push force.]
- Wind lifts a seed into the air. What force brings the seed back down to the ground?
[anno: Gravity brings the seed back down to the ground.]
- How do birds use air currents?
[anno: Birds use the warm air currents by riding the warm air upwards.]
- How is the way the wind affects seeds different from the way the wind affects birds?
[anno: The difference between the way the wind affects seeds and birds is that seeds are pushed along by the wind, and birds push themselves through the wind.]