Air Masses Fronts And Cyclones

Air Mass: An air mass may be defined as a large body of air whose physical properties, especially temperature and humidity are more or less uniform horizontally for hundreds of kilometres.

Fronts: A Front is that sloping boundary which separates two opposing air masses having contrasting characteristics in terms of air temperature, humidity, density, pressure and wind direction.

Classification of Fronts

Warm Fronts : Warm front is that gently sloping frontal surface along which warm and light air becomes active and aggressive and rises rapidly over the cold and dense air.

Cold Fronts : In this front, cold and heavy air is active and uplifts the warm and light air.

Cyclones

Cyclones are centres of low pressure surrounded by closed isobars and having increasing pressure outwards. It has closed air circulation from outside towards the Central low pressure in such a way that air blow inward in anticlockwise in the Northern Hemisphere and clockwise in the S. Hemisphere. Cyclones range in shape circulars, elliptical to 'V shaped. Cyclone-immense influence on the climate and weather. Wherever they reach, they alter the temperature and precipitation conditions of the place. The origin of these cyclones is associated with the polar fronts, where two contrasting air masses converge.

Cyclones are of Two Types

1. Temperate Cyclones : These may becircular, elliptical contrasting air masses e.g. warm, moist and light tropical air masses (westerly winds) and cold and dense polar air masses. After their formation, temperate cyclones move in easterly direction under the influence of westerly winds and control the weather conditions in the middle latitudes. The path followed by these cyclones is called 'Storm Track'.
2. Tropical Cyclones: This type of cyclones developed in the regions lying between the Tropics of Cancer and Capricorn are called Tropical cyclones. The weather conditions of low latitudes mainly rainfall regimes are largely controlled by tropical cyclones. Tropical cyclones usually develop in summer season in the vicinity of Inter-Tropical Convergence Zone (ITCZ) over warm ocean surface.