Air Mass
Air Mass - It is an extensive portion of an atmosphere whose physical properties such as temperature, moisture, lapse rate and humidity are homogeneous for both horizontal and vertical direction.
Characteristics of Air Mass
- The source area should be uniform and homogeneous stretching over a large surface. For example - An extensive desert region, an open ocean, a large plain region like Siberian plain, North American plains, etc.
- Winds should be light and divergent which exists mainly across the high pressure belt with anti-cyclonic circulation which results in stability.
- The temperature should be uniform in horizontal direction with gradual change in vertical direction.
- Humidity should be uniform with very less variability in moisture content.
Classification of Air Mass
1. On the basis of Source
- Continental Air Mass (c)
- Maritime Air Mass (m)
2. On the basis of Temperature
- Warm Air Mass (w)
- Cold Air Mass (k)
3. On the basis of Pressure/Stability
- Stable Air Mass (s)
- Unstable Air Mass (u)
4. On the basis of Latitude
- Arctic Air Mass
- Antarctic Air Mass
- Polar Air Mass
- Tropical Air Mass
- Equatorial Air Mass
Note - At Equatorial region, Air Mass is formed over the ocean not on the continent (landmass) because of strong convection over landmass which prohibits the formation of Air Mass.
Significance of Air Mass
- Air Mass transport heat from one region to another and helps in maintaining balance in global temperature.
- Maritime Air Mass bring more moisture towards the continental regions increasing the humidity level in the region, which may lead to precipitation.
- The interaction of cold and warm Air Mass in temperate regions leads to the formation of fronts and temperate cyclones.
- The Maritime Air Mass of Indian Ocean affects the amount of rainfall in India and South Asia through Indian Monsoon as well as leads to the formation of tropical cyclones.
- The dry Air Mass along the Sub-tropics results in arid condition.
- The cold Air Mass from Siberia affects the temperature of regions for a long distance and causes cold conditions during winters.
Front - Front is a narrow zone of transition dividing two Air Masses of differing temperature and humidity characteristics.
Temperate region is the zone of interaction of two different Air Masses and the fronts are commonly developed along these mid-latitude regions.
The process of formation of fronts is known as Frontogenesis. Whereas the process of decay of front is known as Frontolysis.
Types of Fronts
1. Warm Front -
- It is the boundary between warm and cold Air Masses where the former is advancing and over-riding the cold air mass.
- The gradient of front is gradually leading to slow ascending of warm air resulting in the formation of Stratonimbus clouds and steady rainfall over large area.
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2. Cold Front -
- It is the boundary between warm and cold air mass where the cold air mass is advancing and undercutting the warm air mass.
- This results in steeper gradient along the front leading to rapid ascend of warm air and formation of cumulonimbus clouds which results in heavy rainfall over a small region.
3. Occluded Front -
- It is the later stage of the front formation where the air in the warm sector is no longer at the ground surface.
- It is a compound zone with warm and cold fronts characteristics.
.jpg "occluded front")
4. Stationary Front -
- It is the type of front where the two air masses is unable to push each other and the position of the front does not change.
- Once it is disturbed, it leads to warm or cold front.
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Next Article - Tropical and Temperate Cyclones
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Note - This is my Vision IAS Notes (Vision IAS Class Notes) and Ashutosh Pandey Sir's Public Administration Class notes. I've also added some of the information on my own.
Hope! It will help you to achieve your dream of getting selected in Civil Services Examination 👍
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