Low pressure and depressions
An area of low pessure is called a In meteorological terms, a depression is an area of low air pressure. :
- 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
Question
Are the following statements true or false?
- High pressure brings a depression weather system.
- Low pressure is shown on an isobar map when the numbers are 1000mb or below.
- Depressions will bring rain.
- Winds will be calmer in a depression.
- Depressions move in an anticlockwise direction.
- False - Low pressure brings a depression.
- True
- True
- False – Depressions bring high winds shown by isobars closer together.
- True