Arctic Air Masses

Arctic Air Masses 

air masses forming over the arctic. They are characterized by low temperatures and low humidity and are very clear. As a result of cyclone activity, arctic air masses may be displaced to lower latitudes, where they cause a drop in the temperature. Intrusions of arctic air masses are most frequently observed in the region between Iceland and Greenland, over the Kara Sea, the East Siberian Sea, and in the area of Alaska. In their movement to the south in Eurasia, arctic air masses may reach as far as the Mediterranean, the plains of Middle Asia, and Siberia, but they are contained by mountain chains (the Alps, the Caucasus Mountains, and others); in North America, they may advance unhindered as far as Florida. The properties of arctic air masses change when they are displaced to lower latitudes depending on the state of the surface features. The ground temperatures in fresh intrusions of arctic air masses in winter are higher than in stable continental anticyclones; however, with time the temperatures drop under the influence of the strongly chilled surface of the continent. Spring incursions of arctic air masses over the warmed surface of a land mass are accompanied by the formation of convective clouds and precipitation in the form of rain. In the summer, arctic air masses are quickly warmed over the continents, and their relative humidity decreases quickly. Frequent recurrence of arctic intrusions in the steppe zone leads to droughts.

S. P. KHROMOV