ilmamassa

An ilmamassa, or air mass, is a large body of air that has relatively uniform temperature and humidity characteristics at a given altitude, formed when air remains over a relatively homogeneous surface for an extended period. These masses can cover thousands of square kilometers and typically extend through a significant portion of the Troposphere, with properties controlled by the surface where they originated.

Air masses form over extensive, relatively uniform source regions such as tropical land (creating continental tropical, cT), tropical oceans (maritime tropical, mT), polar land (continental polar, cP), or polar oceans (maritime polar, mP). In some classifications, arctic or Antarctic sources (cA or mA) are included. The moisture content of an air mass depends on whether its source region is land or sea, while its temperature reflects the prevailing season and latitude.

As air masses move with the prevailing winds, they interact at the boundaries where unlike masses meet. Fronts form when a warmer air mass advances over a cooler one (warm front) or when a cooler air mass advances into warmer air (cold front). These interactions often produce clouds, precipitation, and changes in temperature and wind. The dynamics of air masses are central to weather forecasting, including storm development and regional climate patterns.

Meteorologists study air masses using radiosondes, satellites, and surface observations to track their origins, movements, and interaction with fronts.