What are Anticyclones?

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What are Anticyclones?

An anticyclone is a region of high pressure that leads to prolonged periods of fine, dry, and stable weather. This phenomenon occurs because the cold air is descending within the high-pressure system, preventing the formation of clouds.

You can identify high-pressure systems on a synoptic chart or satellite image through the following characteristics:

  • A large area of widely spaced isobars, where pressure is higher than surrounding areas (above 100o mb)
  • The absence of fronts and clouds
  • No rainfall due to the lack of clouds

Features of Anticyclones:

  • Isobars are spread out, signifying gentle winds. Few isobars indicate calm conditions stemming from a slow change in air pressure. These systems can linger for multiple days.
  • Winds blow clockwise in high-pressure areas in the northern hemisphere, following the isobars. The wind direction can be determined by tracing the isobars in a clockwise pattern, with gentler winds when the isobars are far apart.
  • Dry conditions (no rain) are present as the skies remain clear with minimal cloud coverage. This results from cold air sinking in an anticyclone or high-pressure system.
  • Temperature varies with the seasons in anticyclones. The weather can be hot in summer, even leading to heat waves. Conversely, winter anticyclones bring cold temperatures, with a likely occurrence of frost and occasional mist and fog.


  • An area of high pressure causes dry and stable weather, with seasonal temperature variations due to descending cold air.

  • High-pressure systems can be identified on synoptic charts or satellite images by widely spaced isobars above 1000mb, the absence of clouds and fronts, and no rainfall.

  • Features of anticyclones include gentle or calm winds (spread out isobars), clockwise wind direction in the northern hemisphere, dry conditions with clear skies, and weather that can range from heat waves in summer to frost and fog in winter.


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