Iceland Low

one of the major centers of atmospheric activity in the northern hemisphere; a region of low atmospheric pressure in the North Atlantic Ocean. The main center of the low on sea-level weather maps is situated between Iceland and southern Greenland, where in January the pressure is less than 996 millibars; in winter other centers may be found west of Greenland and above the Barents Sea. In summer the Iceland low weakens and divides into two centers, one above the Denmark Strait and the other west of Greenland. Along the southern periphery of the Iceland low the air at the earth’s surface is carried from the Atlantic Ocean toward Europe, which helps to create an oceanic climate in Western Europe. With increasing altitude the Iceland low rapidly spreads to the northeastern regions of North America, toward minimum air temperatures, and becomes a trough of the subpolar low, which causes a westerly shifting of air in the greater part of the troposphere and lower stratosphere of the northern hemisphere. On maps showing atmospheric pressure over many years, the Iceland low reflects the predominance of deep and persistent cyclones over anticyclones, especially in winter.