Unit 3 Nature’s Energy 1

3. Wind Energy

The sun heats air by convection The convection currents that move through heated water also Move through heated air

The moving air is called wind You cannot see wind, only the results of the wind energy

Vocabulary Wind energy Energy of moving air

Wind is caused by heat from the sun The sun warms the surface of the Earth

Some parts of Earth’s surface, such as roads and beaches, absorb or take in more heat than others

The air over these areas becomes warmer than the air around them This warm air rises, and the cool air around it moves in to take its place

This convection current happens anywhere that air becomes heated Sometimes the air moves slowly

You cannot feel the wind when it moves slowly Sometimes it moves fast.

Any matter that is moving is using Wind is a source of mechanical energy Any matter that is moving is using mechanical energy

The wind can move things. A very strong wind can push over trees and buildings

One of the ways people first used wind energy was to power sailboats. As the wind pushes against the sails, it moves the boat across the water

are another way people use Windmills are another way people use wind energy

A windmill has flat blades on a wheel Wind pushes the blades and makes the wheel turn.

The energy of the turning wheel can be used to pump water from a well It can also be used to make electricity

People have been using windmills for more than a thousand years