High pressure systems
Anticyclones
Clear blue sky with the Royal Air Force Red Arrows aerobatic display team
An High-pressure systems, giving clear skies and gentle wind. is an area of high pressure which brings long periods of settled weather. An area of heavy cool air sinks and it warms up as it does so. As it warms it is able to hold more moisture. This means clouds do not form. High pressure systems can be identified from a synoptic chart due to:
- widely spaced isobars
- no fronts/clouds
- isobars showing pressure increasing outwards from the centre and above 1008mb
High pressure characteristics
Isobars are spread far apart bringing gentle winds. This is caused by a very gradual change in air pressure. Because of the gentle winds these systems can remain in place for several days.
- Wind - winds blow clockwise in high pressure and wind blows along the isobars. Wind blows gently when isobars are widely spaced.
- Temperature - in summer, skies are clear with little cloud and temperatures are high, while in winter, skies are also clear with little cloud, but temperatures are cold and there is a likelihood of frost and fog.