Anticyclones, which have high atmospheric pressure and sinking air, are the polar opposite of cyclones. Because the air is sinking rather than rising, no clouds or rain form. This is because as the air sinks, it warms, allowing it to hold more water. This article will explain Anticyclones, which will help you prepare for the UPSC Civil Service Exam in Geography.
Read More: Tropical Cyclone
Anticyclones are pressure centres. They are surrounded by closed isobars with decreasing pressure outward. Air blows outward in a clockwise direction in the Northern hemisphere and an anticlockwise direction in the Southern hemisphere due to the circulation from a central area of high pressure to the periphery. Blowing winds are deflected from their paths to the right in the Northern hemisphere and left in the Southern hemisphere due to Coriolis Force, which is how a flowing system becomes circular.
The pressure difference between the centre and periphery of an anticyclone is typically 10 to 20 mb, but can be higher. Because the diameter is 75% larger than that of Temperate Cyclones, they are much larger in size and area.
Temperate anticyclones are so widespread that one anticyclone can cover nearly half of the United States. The course is extremely variable and unpredictable. They move slowly and occasionally become stationary over a specific location for four days. An anticyclone’s average speed ranges from 30 to 50 km/h. Either a polar cold air mass or warm tropical air mass descending causes anticyclones to occur.
These anticyclones are high-pressure systems that are more common in subtropical and polar high-pressure belts where air sinks from the upper troposphere to the lower troposphere, but they are almost non-existent in equatorial regions.
Read More: Water Cycle
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.
Read More: Climate of India
In most cases, as a cyclone moves away, an actively developing Anticyclone forms over a ground located in the region of cold air behind it.
Also Read: Cyclone Biparjoy
In the summer, anticyclones are frequently regions of clear skies and sunny weather; at other times of the year, cloudy and foggy weather, particularly over wet ground, snow cover, and the ocean, maybe more typical. Winter anticyclones produce colder-than-average surface temperatures, especially if the skies remain clear. Anticyclones cause periods of little or no rain, which can be prolonged when combined with blocking highs.
Read More: Evaporation and Condensation
1. Cold Anticyclones
These cyclones also known as thermal anticyclones, form above the Polar Regions as a result of air sinking. Post-subsidence of polar air outflows in an easterly and southeasterly direction.
2. Warm Anticyclones
These also known as dynamic anticyclones, form above warm subtropical regions as a result of air sinking from the upper troposphere to the lower troposphere and resulting in air divergence.
3. Blocking Anticyclones
These form as a result of an obstruction in the upper troposphere’s air circulation that develops over mid-latitudes and are called blocking because they obstruct the flow of temperate cyclones in the mid-latitudes.
Anticyclones tend to produce weather that is fairly consistent. Whence descends from above at the centre, the weather becomes clear and rainless due to atmospheric stability brought about by the descending wind. Anticyclones dominate the weather in Canada, the United States, and northern Eurasia.
Read More: Humidity
- When combined with blocking highs, anticyclones cause periods of little or no rain that can last for days or weeks.
- They aid in the recharge of aquifers.
- Anticyclones aid in the regulation of ocean temperatures.
- By increasing the flow of rivers and streams that carry garbage, anticyclones pull nutrients into the sea.
Read More: Fronts
Difference between AntiCyclones & Cyclones
|They have low pressure at the centre, surrounded by high pressure on all sides.||They have high pressure at the centre, surrounded by low pressure on all sides.|
|Winds blow towards the centre.||Winds radiate out from the centre.|
|Winds are violent and destructive.||Winds are mild and not destructive.|
|Winds blow in anti-clockwise in the northern hemisphere and clockwise in the southern hemisphere.||Winds blow in a clockwise direction in the northern hemisphere and anti-clockwise in the southern hemisphere.|
|They present cloudy weather accompanied by thunder, lightning and heavy rain.||They present calm and clear weather.|
Read More: Precipitation
Although anticyclones are not as well studied as cyclones, they are important because the clear and dry conditions associated with them can allow for strong nighttime radiative cooling and cold surface temperatures. Pollutants may accumulate near the Earth’s surface due to the convectively stable air of anticyclones. Finally, the anticyclones’ blocking action above the Earth’s surface may result in consistently abnormal weather conditions.