Weather fronts are the boundaries between air masses with different characteristics such as temperature, humidity, and air pressure.
An air mass is a large parcel of air with roughly the same temperature, humidity, or pressure throughout. Different air masses tend not to mix. The clashing of two or more air masses is what causes severe storms. The front is literally the “front end” of an air mass.
Movement of a front will depend largely on the conditions inside the air mass. Air masses tend to be either moist (maritime) or dry (continental) in humidity content. Temperatures are either cold (polar) or warm (tropical). The weather map symbols used for fronts are indicated above. Go to the answers for the types of fronts pictured above.