There are four main types of air masses that form in different regions and have distinct temperature and moisture properties: continental, maritime, polar, and tropical. Weather fronts occur when different air masses meet, with three main types being cold fronts, warm fronts, and stationary fronts. Cold fronts move quickly and can produce thunderstorms and cooler temperatures, while warm fronts move more slowly and bring humid conditions and rain. Stationary fronts occur when air masses meet but neither overtakes the other, resulting in prolonged, unchanging weather.
![Air Masses ,[object Object],http://www.weatherquestions.com/What_is_an_air_mass.htm](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)