In the context of weather and climate, what is a depression?

A depression is a huge area of low pressure that measures many 100s of km. Characteristics: ● Such low atmospheric pressure, often below 1000mb. ● Shown on a weather map by closed isobars with decreasing pressure towards the centre. Isobars usually close together, meaning steep pressure gradient from outer edges to centre. ● They move rapidly from W to E across British Isles. ● Produce strong winds which blow inwards towards centre of the low in an anticlockwise direction. ● Often in S of Britain, winds will veer, as the wind direction changes from S to SW to W to NW as depression moves from W to E. ● In N of Britain, winds said to back as they change direction from SE to E to NE to E. ● They bring most of Britain’s rain and cloud.