U6W2 Wind Power

Wind Power

CHAPTER 1 WHAT IS WIND? Have you ever been outside on a windy day?What did the wind feel like? Could you feel it push against you as you walked? The wind can blow a leaf off a tree, keep a kite in the sky, or even push a sailboat. For thousands of years, people have used wind power to sail across rivers and seas. People had sailboats in ancient Egypt. They sailed up and down the Nile River. They would load their sailboats with goods and carry them down the river. Later, people set sail from Europe. They sailed across the oceans. They discovered new places, including the Americas. Some people even used sailboats to travel around the world The mainsail captures wind energy to move the sailboat.

Just what is wind, anyway?Wind is moving air. The wind can be breezy and calm. It can also be very powerful, causing damage to our homes. Wind has kinetic energy, the force that moves things. Wind gets this energy from the sun. First the sun's heat warms the air. Warm air, which is lighter than cool air, rises up. Then cooler air takes its place. This moving air is the wind. Cool air Warm air Energy from the sun warms the air over land more quickly than the air over water.

CHAPTER 2 WINDMILLS Sailboats were not the only way that people used wind power long ago. They also built windmills. Windmills help capture energy from the wind. They make it possible for us to use wind power to do work. Let's take a closer look at windmills. They have long arms. These arms move in a circle when the wind blows on them. The turning arms provide power for machines inside the windmill. This windmill was built in 1902 to pump water in Golden Gate Park in San Francisco, California.

The History of Windmills People can use windmills to pump water. In the 1800s and 1900s, Americans built windmills for this purpose. Many people had ranches and farms in dry places. They couldn't just haul buckets of water from rivers. Instead, people used windmills to pump water up from deep underground. Then they could use the water for drinking, cooking, watering crops, and feeding farm animals. On dry ranches in Texas, windmills are used to pump water for cattle.