An air mass is a large body of air that has uniform temperature and humidity characteristics.

The four main types of air masses are: maritime tropical, maritime polar, continental tropical, and continental polar.

A warm front occurs when a warm air mass moves over a cold air mass, leading to gradual temperature increases and often precipitation.

A cold front occurs when a cold air mass pushes into a warm air mass, causing abrupt weather changes and often thunderstorms.

An occluded front forms when a warm air mass is caught between two cold air masses, causing the warm air to rise.

A stationary front occurs when two air masses meet but neither is strong enough to replace the other, leading to prolonged weather conditions.

An air mass that forms over land is typically dry (continental), while one that forms over water is usually moist (maritime).

A maritime tropical air mass is warm and moist, typically forming over warm ocean waters.

A maritime polar air mass is cold and moist, usually forming over cold ocean waters.

A continental tropical air mass is warm and dry, forming over hot land areas.