Low pressure and depressions
An area of low pessure is called a depression:
- The low pressure of a depressions causes clouds and rainfall to form.
- Depressions therefore bring unsettled weather and rain.
- Winds are normally stronger, shown by the isobars being closer together.
- Depressions usually form over the Atlantic Ocean and are carried across Britain by westerly winds and move in an anticlockwise direction.
You can recognise a depression on a weather chart:
- the isobars are below 1000mb and are packed closer together
- a warm front (red line) is followed by a cold front (blue line)
You will learn more about warm and cold fronts in National 5 Geography