antisykloni

Antisykloni, or anticyclones, are large-scale high-pressure systems in the Earth's atmosphere. They are characterized by descent of air, a rise in surface pressure, and winds that circulate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. The subsiding air suppresses cloud formation, leading to clear skies and relatively stable weather in many regions.

Formation and dynamics: Antisykloni form when air aloft diverges and cools, or when subsiding air accumulates at the surface, often associated with ridges of high geopotential height. They can persist for days to weeks, especially when they become blocking patterns that slow or halt the progression of mid-latitude cyclone systems.

Weather and impacts: Typical conditions include calm to light winds, bright sunshine, and minimal precipitation. Nights in anticyclones tend to cool rapidly due to radiational cooling, producing frost in winter and fog in some situations. In summer, persistent anticyclones can produce heat waves and drought by maintaining stable, hot conditions for extended periods.

Global distribution and significance: Subtropical high-pressure belts create well-known systems such as the Azores High and the Pacific High, which influence weather patterns over adjacent continents. Continental and regional anticyclones, like the Siberian High, affect seasonal climate in large regions. The position and strength of antisykloni help shape regional weather, climate anomalies, and the occurrence of blocking events that disrupt typical storm tracks.

See also: High-pressure system; Blocking pattern; Meteorology.