It can destroy buildings and pick up cars and trains, throwing
them hundreds of metres into the air. It can make a cool day
feel bitterly cold and it can make a hot day feel nice and
cool. But what is wind and why does it occur?
is simply air - the stuff we breathe- moving across the surface
of the Earth. It does this because the Sun warms the air over
the middle part of the Earth - the Equator - and this sets
up a series of wind patterns across the globe.
are recorded in kilometres (or miles) per hour. The weather
instrument used to measure wind is called an anemometer. It
has a series of cups which rotate as the wind hits them and
the faster they rotate, the higher the wind speed.
The wind direction is the direction from which the wind blows.
(So a westerly wind blows from the west towards the east.)
Windy weather is common in the West Country. The prevailing
wind (the direction from which the wind usually blows) is
southwesterly. Winds of up to 90 miles per hour have been
recorded in Bristol. These very strong winds are called gales.
Much stronger winds are found in other parts of the world.
are the biggest storms on Earth and winds of 150 MPH may be
found within their swirling cloud systems. The very strongest
winds have been measured in tornadoes. These are violent swirls
of air, similar to the way water drains down the plughole
in the bath. The biggest of these are usually found in the
United States of America. A gust of 286 MPH was once recorded
in one of these ‘twisters’. But winds are of great importance.
Most plants need wind to transport their seeds. Many species
of bird need the wind to soar above the oceans or to help
them on their migrations. The wind can help us too.
power of the wind can be harnessed to provide us with energy.
Wind farms change the energy of the wind into electrical energy
which can then be used to power our homes and schools. This
is a non-polluting form of energy which does not produce any
of the gases which cause global warming.