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Home > Schools Resources > The Wind
Energy Research Unit

Schools Resources: the Wind

Wind is moving air and is caused by differences in air pressure within our atmosphere. 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 and water formations, it absorbs the sun’s radiation unevenly. As the sun warms the Earth's surface, the atmosphere warms too. Warm air near the earth's surface will tend to rise, so a mass of low pressure is an area of air that is rising. If air temperature falls, the air pressure will increase as cool air sinks towards the ground.

Air under high pressure moves toward areas of low pressure - which is why the wind blows. The greater the difference in pressure, the faster the air flows . A wind speed of 318 mph was measured in an Oklahoma tornado in 1999 - the highest wind speed yet recorded!

Wind is described with direction and speed. The direction of the wind is expressed as the direction from which the wind is blowing. For example, easterly winds blow from east to west, while westerly winds blow from west to east. Winds have different levels of speed, such as “breeze” and “gale”, depending on how fast they blow. Wind speeds are based on the descriptions of winds in a scale called the Beaufort Scale, which divides wind speeds into 12 different categories, from less than 1 mph to more than 73 mph.

ERU has been involved in several projects to assess and improve wind farm site specific forecasts of wind power up to a day ahead to help with power load planning.


There's a lot of energy available in the wind, as this picture of Hurricane Katrina shows

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Energy Research Unit at Rutherford Appleton Laboratory www.eru.rl.ac.uk
Energy Research Unit
Rutherford Appleton Laboratory
Science & Technology Facilities Council