An air mass is a large area of uniform, stable air spreading over hundreds, thousands or millions of square miles. Air masses are usually associated with the region over which they develop; for example, there are continental polar and tropical air masses.
According to Science Clarified, an air mass develops over areas with uniform, unchanging surface features such as deserts, plains and oceans spreading over vast areas. These features allow a mass of air to develop without the obstruction of mountains and intersections of land and water.
For the successful formation of an air mass, stable weather conditions need to be present; high winds will disperse a formed air mass.
A frontal system is a boundary area of transitional air between two air masses. Fronts appear when an air mass of either cold or warm air is replaced by a contrasting mass of air.
A warm front occurs when a mass of cold air is replaced by an air mass with higher temperatures and increased humidity.
The derivation of the word "front" is from a military battlefront where two opposing forces come into contact with each other, according to Science Clarified.
