Wind What is wind Wind is air in

Wind

What is wind? • Wind is air in motion. • It is produced by the uneven heating of the Earth’s surface by the sun. • Since the Earth’s surface is made of various land water formations, it absorbs the sun’s radiation unevenly.

What causes wind to blow? • 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 cold air, rises. • Then cool air moves in replacing the warm air. • This movement of air is what makes wind blow.

Atmospheric pressure • Low atmospheric pressure = areas where hot air is rising. • High atmospheric pressure = areas where cool air descends toward Earth. • Air moves: high pressure areas low pressure areas.

Facts about wind • Winds are named after the direction from which they blow.

Facts about wind • The wind that is most frequent in an area is called the prevailing wind. • What is Ireland’s prevailing wind?

Facts about wind • Winds that blow from the equator to the poles are warm winds. • Winds that blow from the poles towards the equator are cold winds.

HP LP 60ºN 30ºN Equator

Coriolis Effect Earth spins on its axis from west to east. This changes the direction of winds: • Winds are deflected to the right of their direction in the northern hemisphere • Winds are directed to the left of their direction in the southern hemisphere