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.