is the weight of air pressing down on the earth's surface. Pressure
varies from place to place and and results in pressure systems.
is low pressure?
times of low pressure the air is usually rising. As the air rises,
it cools, condenses and forms clouds. Areas of low pressure are
known as depressions.
occur when warm air meets cold air. The point where warm air meets
cold air is called a front. Along the front there is usually cloud
and rainfall. This occurs because the warm air cools and condenses
when it meets the cold air (you can find out more about frontal
or 'lows', bring rain, strong winds and changeable conditions.
Changeable weather is a feature of British weather, depressions
are responsible for much of this.
blow in an anti clockwise direction.
is high pressure?
above average pressure are called anticyclones. Anticyclones occur
when air is sinking. As a result there are usually few clouds
in the air. In the UK anticyclones bring cold clear days in winter
and hot and sunny days in summer.
blow in a clock wise direction.