Whoosh! You know that wind is moving air. But what causes the air to move? It’s the uneven heating of the earth’s atmosphere.

As the sun warms the earth’s surface, the atmosphere warms too. Some parts of the earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cool air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow.