Different Types of Anti Cyclones

There are meteorological events on our globe related to atmospheric pressure and the large-scale circulation of air. One of these events is the cyclone. Cyclones occur when air masses rotate at high speeds in one direction, resulting in an adverse climatic condition with low atmospheric pressure. It also has a counterpart, the anticyclone, mostly encircled by circular isobars. It is a phenomenon that allows for a clear sky without a downpour. An Anticyclone affects the ecosystem in various ways and puts enormous stress on it. 

What are Cyclones and Anticyclones?

According to the definition, Cyclone is a huge mass of air that swirls around the center of  a low air pressure area. When seen from above, they rotate anti-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. 

Cyclones are identified by winds spinning towards the center point (inward spiral) revolving around a low-pressure zone. They are bordered mainly by closed isobars with rising air pressure towards the outer boundary. In the center of a cyclone, the air circulation is completely closed from outside. 

An Anticyclone is a high-pressure system. It is a huge mass of wind circulating through a center of high pressure. When observed from above, it swirls clockwise or rightward in the Northern Hemisphere and anti-clockwise or leftward in the Southern Hemisphere. 

Formation of Anticyclones

Anticyclones are generated in a number of different ways. They are formed based on various parameters, including their moist-convection, magnitude, intensity and Coriolis force, to name a few. Because of the weak pressure gradient, the wind system in anticyclones is very light and underdeveloped. The winds blow from the high-pressure center to the low-pressure boundary. Compared to the front, the winds are much slower at the back. The center of an anticyclone is dominated by gentle breezes caused by the sinking of either polar cold air or warm tropical air mass.

Anticyclones are formed in higher latitudes. Usually, they occur in the warm, subtropical high-pressure systems.

Anticyclone Characteristics

• They usually have the shape of a circle. The differential pressure between the anticyclone’s center and perimeter is typically 10-20 Mb.
• Fronts do not exist in anticyclones.
• They are substantially bigger than temperate cyclones in terms of size and area.
• Winds fall from above near the center, causing atmospheric stability and resulting in clearer weather and less rain.
• The weather, the nature of the air mass      and the humidity in the air all influence the temperature of anticyclones.

Types of Anticyclones

Anticyclones can be of three types, namely

• Surface-based systems
• Mid-tropospheric systems
• Upper tropospheric systems

Effects of Surface-based Anticyclones

Anticyclones have different effects depending on the nature of the system. Hot masses of air and cloudless sky are common outcomes of surface-based systems. These heated masses of air are created by the sinking of air in the troposphere’s upper reaches. Clear skies indicate the absence of clouds to restrict the quantity of sunlight received by the Earth, resulting in high surface temperatures. The clear skies at night imply that heat radiation from the ground does not meet any barriers, resulting in cooler temperatures. With the rise in the humidity, fog can develop overnight in some cases.

The type of weather this anticyclone creates is also determined by its source. The anticyclones created in the northern hemisphere and moving south have a cooler base. It doesn’t let clouds form and results in clear weather. High pressure in hotter regions around the coasts, on the contrary, has the power to bring precipitation to these areas. It is because the systems travel over a vast stretch of the oceans.

Effects of Mid-tropospheric Anticyclones

The air circulation in the mid-tropospheric region doesn’t allow air to mix in the middle and lower part of the troposphere. As a result, thunderstorms are significantly decreased, and pollutants like ozone are confined at the troposphere’s base. During the summer, the entrapped pollutants generate extreme heat in some regions. Mexico City and Los Angeles are a few instances where the weather remains extremely hot during the summers.

Effects of Upper Tropospheric Anticyclones

Due to divergence on the upper levels, anticyclones at higher altitudes cause confluence on the surface of the Earth. Rain and thunderstorms may occur in some conditions, like when lower atmospheric regions are humidified. Because this process causes sea surface temperatures to fall below 79 °F approximately, these thunderstorms and showers will gradually fade.

Conclusion

Anticyclones are high-pressure systems surrounded by circular isobars. They are divided into three broad groups. Anticyclones have varied effects depending on the type of system. The different types of anticyclones are surface-based systems, mid-tropospheric systems, and upper tropospheric systems. The above article unpacks the definition of cyclones and the formation, characteristics, and types of anticyclones over the Earth’s surface.