Air-Mass Modification

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Air-Mass Modification

 

a change in the properties of a tropospheric air mass when the air mass moves to different latitudes or over an underlying surface different from that of the source region—for example, when the air mass moves from the sea to the land or vice versa.

In air-mass modification the air mass is warmed or cooled, its water-vapor and dust contents decrease or increase, the nature of the cloud cover changes, and other air-mass characteristics are modified. When a radical change in the properties of an air mass occurs, the geographic classification of the air mass is altered. For example, cold arctic air masses that reach the southern USSR in the summer are intensely warmed and dried and become filled with dust, thus acquiring the characteristics of continental tropical air, which often causes droughts.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.