Types of Air Masses and Fronts

1. Air Masses:

If the surface is warm and moist, air in the region becomes warm and moist also. If the air then moves to different regions it takes these properties along, gradually changing in response to the new area. Air masses are designated as cold or warm and moist or dry.

Cold air masses:

• Originate over the pole and near the polar region.
• Warm air masses originate from tropic and sub tropic.
• The air masses that originate over tropical oceans are moistest.
• Whereas mass from over cold, dry land are driest.

Continental polar mass:

Cold and dry air masses that originate over landmass are called continental polar mass.

Maritime Polar mass

Cold and moist air masses that originate over water are called maritime polar mass.

Continental tropical mass:

Warm and dry air mass originating over land mass

Maritime tropical mass:

Warm and humid air mass originating over water

2. Front:

It is a boundary between two air masses. The term has its origins analog to military operations as the armies in battle encounter each other at the front. There are two types of front:

A. Cold Air front:

If cold air advances, the air front is called cold air front

B. Warm air front:

If cold air retreats, it is called warm air front.

C. Stationary air front:

If cold air neither advances nor retreats, it is a stationary front.

D. Occluded/Occlusion:

When cold front overtakes warm front or warm front overtakes cold front.

3. Cyclone:

A cyclone is more or less circular area of low atmospheric pressure in which the wind blows counterclockwise in the northern hemisphere. A typical cyclone is a large whirling mass of air ranging 500-100 miles or more in diameter and with a velocity of 300miles/hr. At the center of the cyclone the barometric pressure is less. In northern hemisphere the wind reaches the center spirally in counter clockwise direction with a vertical component. The central portion acts as a chimney through which air rises, expands, cools and produce condensation and usually precipitation.

4. Hurricane:

It is a tropical cyclone 300 miles in diameter with a speed of 74 miles/hr or more, which forms over warm ocean water in maritime tropical air.

5. Tornado:

A rotating air accompanied by a funnel shaped downward and having several hundred yards in diameter whirling destructively at speed of 300 mph

6. Typhoon:

Every tropical ocean in different locations use different masses as typhoon (western pacific) Cyclone (Indian Ocean)