Air mass means a large body of air whose
properties are essentially homogeneous. Front is the boundary or zone of transition between two
air masses of different temperature or humidity, which thus differ in density. Frontal zone
inclines to the cold air mass, the warm air climbs above the cold air, and the cold air inserts
to the lower part of the warm air. Types of fronts include cold front, warm front and stationary
front etc.
