Air Masses form where there is persistent atmospheric conditions. In regions where cyclones dominate, the air near the surface is constantly changing as air is brought into the region from surrounding regions.
Regions dominated by anticyclones tend to have light winds and generally clear skys.
These regions are shown above. Fronts Fronts are boundaries between contrasting air masses One air masses is warmer than the other and therefore more bouyant. Where the two air masses meet the warmer, more bouyant air mass with be uplifted relative to the colder, more dense air mass. Because of their steep slope, air rises quickly, condenses and cause large rain storms but they are limited in areal extent. Stationary fronts are usually similar to a cold front in structure, but neither air masses have moved substantially.