Anticyclones are the polar opposite of cyclones, characterised by high atmospheric pressure and sinking air. No clouds or rain form because the air is sinking rather than rising. This is due to the fact that as the air sinks, it warms, allowing it to hold more water.
- As a cyclone moves away, an active anticyclone forms over a ground site in the cold air zone behind it.
- An anticyclone forms before the next cyclone enters the area.
- These are also known as cold anticyclones.
- In contrast, the downward air velocity in an anticyclone compresses the descending air.
- As a result of the compression, the air warms.
- As a result, the air forming the anticyclone at altitudes of 2 to 5 km (1 to 3 miles) above the ground warms over time, and the anticyclone eventually becomes a warm anticyclone.
- They can last a week or more, and a small number of these blocking anticyclones can completely alter the course of a season.
- Sun-blocking anticyclones are particularly common over Europe, the eastern Atlantic, and the Alaskan region.
Types of anticyclones:
- Cold anticyclones or thermal anticyclones: They are formed above the Polar Regions due to the sinking of air. Post subsidence of air outflows from the polar region in an easterly and southeasterly direction.
- Warm anticyclones or dynamic anticyclones: They are formed above warm subtropical regions due to the sinking of air from the upper troposphere to the lower troposphere and consequent divergence of air.
- Blocking anticyclones: These developed due to obstruction in the air circulation in the upper troposphere that develops over mid-latitudes and are called blocking because they obstruct the flow of temperate cyclones in mid-latitudes.
Anticyclones tend to produce fairly uniform weather. Whence descends from above at the center and the weather becomes clear and rainless because the descending wind brings atmospheric stability. The weather of Canada USA and northern Eurasia is mostly affected by anticyclones.
Characteristics of Anticyclones
- They are usually shaped like a circle. The pressure difference between an anticyclone’s centre and its edges is between 10 and 20 mb.
- They are much bigger and cover a much larger area than tropical cyclones.
- After cyclones, there are anticyclones. They move in a very slow way. The average speed of an anticyclone is between 30 and 50 km/h.
- At the centre, winds come down from above, making the sky clearer and causing it to rain less. This is called atmospheric stability.
- In anticyclones, the temperature depends on the weather, the type of air mass, and the amount of moisture in the air.
- There are no fronts in anticyclones.
FAQs on Anticyclones
Ques 1. What is an anticyclone in meteorology?
Ans. An anticyclone is a weather system characterized by a high-pressure area with outward spiraling winds. It is the opposite of a cyclone, and the winds in an anticyclone rotate in a clockwise direction in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.
Ques 2. How do anticyclones form and what are the key factors contributing to their development?
Ans. Anticyclones typically form due to the sinking of cool, dense air, leading to an increase in atmospheric pressure. Factors contributing to their development include subsidence, clear skies, and cooling of the air mass.
Ques 3. What are the weather conditions associated with an anticyclone?
Ans. Anticyclones are associated with fair and calm weather conditions. They often bring clear skies, light winds, and stable atmospheric conditions. They can also lead to temperature inversions, where the temperature increases with height.
Ques 4. How do anticyclones differ from cyclones in terms of weather patterns?
Ans. Anticyclones and cyclones are opposite weather systems. While anticyclones bring stable and clear weather, cyclones are associated with low-pressure areas and bring stormy and unsettled weather, including rain, strong winds, and thunderstorms.
Ques 5. What are the effects of anticyclones on regional and global weather patterns?
Ans. Anticyclones can have significant impacts on regional and global weather patterns. They can lead to prolonged periods of dry and warm weather in some areas and create temperature anomalies. Additionally, they can influence the movement of air masses and the development of weather systems over larger regions.
Read Also : Cyclone Season in Indian Climate