A depression is an area that has low atmospheric pressure. Air rising causes the formation of clouds, which brings rainfall. Depressions often move eastwards across the UK, bringing changeable weather as they travel.
There are usually frontal systems associated with depressions. The diagram below shows the changing weather that the warm and cold fronts bring as they move towards the east.
Anticyclones are areas of high pressure which form when cool air sinks. Anticyclones spin around in a clockwise direction. Anticyclones make skies clear and cause different weather in summer and winter. In summer, anticyclones bring hot, sunny weather. During winter, anticyclones cause cold weather including fog and frost.