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Monsoon air masses are moist and unstable. Superior air masses are dry, and rarely reach the ground. They normally reside over maritime tropical air masses, forming a warmer and drier layer over the more moderate moist air mass below, forming what is known as a trade wind inversion over the maritime tropical air mass.
It is a form of fluid instability found in thermally stratified atmospheres in which a colder fluid overlies a warmer one. When an air mass is unstable, the element of the air mass that is displaced upwards is accelerated by the pressure differential between the displaced air and the ambient air at the (higher) altitude to which it was displaced.
Instability results from difference between the adiabatic lapse rate of an air mass and the ambient lapse rate in the atmosphere. [2] If the adiabatic lapse rate is lower than the ambient lapse rate, an air mass displaced upward cools less rapidly than the air in which it is moving. Hence, such an air mass becomes warmer relative to the ...
This unstable air mass creates strong updrafts, while wind shears will further increase the strength of the updraft, and promotes the rotation of tornadoes. These start out horizontal, then drop ...
The inability of an air mass to resist vertical motion. In a stable atmosphere vertical movement of air is generally difficult, whereas in an unstable atmosphere vertical disturbances can be quite exaggerated, resulting in turbulent airflow and convective activity that may lead to extensive vertical clouds, storms, and severe weather.
Air mass classifications are indicated by three letters: [3] [4] Fronts separate air masses of different types or origins, and are located along troughs of lower pressure. [5] The first letter describes its moisture properties, with c used for c ontinental air masses (dry) and; m used for m aritime air masses (moist).
In general, cumulonimbus require moisture, an unstable air mass, and a lifting force in order to form. Cumulonimbus typically go through three stages: the developing stage , the mature stage (where the main cloud may reach supercell status in favorable conditions), and the dissipation stage . [ 11 ]
This arctic air tends to be colder than polar air. The polar vortex is a large area of low-pressure and cold air surrounding both of the Earth’s poles, according to the weather service. It ...