Air Masses and Fronts

Abstract

Synoptic map analysis, Swedish meteorologist Tor Bergeron (Bergeron) found that in the air above the vast areas, the values of certain meteorological elements change very little in the horizontal direction. He called these large masses of air masses of air. The horizontal dimensions of the air masses are of continental scale (from 500 to 5000 km), while in the vertical direction, they can cover the entire troposphere. Air masses are characterized by temperature, humidity, temperature stratification, and degree of turbidity. Large, synoptic air masses will obviously be discussed here. It should be noted that meteorology also refers to smaller air masses. Air mass is defined as a widespread body of air with uniform physical properties situated over a particular region of the Earth’s surface called air mass source region (e.g. Ahrens 2007; Lupikasza 2000; Hoskins and James 2014; Lackmann 2012). It represents a large volume of air with temperature and moisture regime that tend to be relatively homogeneous in the horizontal direction over wide area. In addition, the vertical temperature and moisture variations are approximately the same over its horizontal extent. Air masses usually undergo specific modifications while in transit away from the source region. The stagnation or long-continued motion of air over a source region permits the vertical temperature and moisture distribution of the air to reach relative equilibrium with the underlying surface. The air mass is separated from the adjacent air mass through the border area, which might be more accurately defined. Where two air masses of different temperatures meet, a boundary forms which is termed a “front”. The air mass is covering thousands of square metres, and it extends vertically through the troposphere.