High pressure systems

Anticyclones

Clear blue sky with The Royal Air Force Red Arrows Aerobatic Display Team
Clear blue sky with The Royal Air Force Red Arrows Aerobatic Display Team

An anticyclone is an area of high pressure which brings settled weather. Cold air is sinking which means clouds do not form. High pressure systems can be identified from a synoptic chart:

  • 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. Due to gentle winds these systems can remain in place for several days.
  • Dry - there are no fronts in an anticyclone so there is no rain.
  • 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.