High Pressure Systems

High-pressure systems are caused by the greater weight of air molecules.
If there is a net gain of air in the upper atmosphere, the air tends to sink toward the surface.
The sinking air causes subsidence.
As the air descends to lower levels, its temperature increases due to adiabatic warming.
Intense high-pressure systems are known as anticyclones.

A high-pressure ridge is an elongated area of high pressure.
Clear weather is generally associated with high-pressure areas because air diverges outward.
Poor visibility is the main aviation hazard in high-pressure systems, as pollutants such as smoke remain trapped near the surface beneath an inversion layer.
According to Buys Ballot’s Law, winds circulate clockwise around a high in the Northern Hemisphere and anticlockwise in the Southern Hemisphere due to the Coriolis effect.
Radiation fog commonly forms during the night and early morning hours.

Globally, subtropical high-pressure belts are located between approximately 20° and 45° latitude, at the boundary between the Hadley and Ferrel Cells.
A net gain of descending air creates the subtropical oceanic high-pressure belt.
The high-pressure belt shifts toward higher latitudes during summer and toward lower latitudes during winter as the Hadley–Ferrel Cell boundary migrates.

Cold anticyclones, or Polar High-Pressure Belts, develop due to the extremely cold land surfaces in the polar regions.
Large and widespread high-pressure belts are found near the poles because land cools more rapidly than the surrounding sea.

Temporary anticyclones develop due to relatively higher pressure between two polar frontal depressions (low-pressure systems).
Negligible cloud, precipitation, icing, and turbulence are generally experienced within a temporary anticyclone.
Blocking Anticyclone: A stationary high-pressure system that blocks the movement of approaching cyclonic circulations.