Chapter 7, Problem 1LC

To determine

The formation of air mass and the reason for air masses rarely originating in the the midlatitudes.

Answer to Problem 1LC

The formation of air mass occurs over an extensive, uniform land or sea surface on the Earth that are associated with stationary or anticyclonic air. An air mass form in distinct source regions that are favorable for its generation. The atmosphere is rarely quiet long enough for an air mass to form in the band of the westerlies (the midlatitudes).

Explanation of Solution

An air mass is a large air parcel that has relatively uniform properties in the horizontal dimension and moves as an entity. Such extensive bodies are distinct from one another and compose the troposphere.

Formation of air mass: An air mass forms when a parcel of air remains in a large, uniform land and sea surface for an extended period to achieve uniform properties. Such regions are termed as source regions. Some of the ideal source regions are the uniform covering of the snow, forest, or desert. These source regions are part of Earth’s surface that is well suited for the formation of air masses, as they are wide, physically uniform, and are associated with the air that is stationary or anticyclonic.

Air mass can form any region in low and high latitudes except but rarely in midlatitudes. This is because the consistent westerlies prevail in those regions, which restrict the formation of the air mass.