Maritime Tropical (mT) air is the most unstable type of air mass, primarily because of the warm, moist air it contains. This warm air rises, leading to increased instability in the atmosphere.

The film features a character named Wesley, who is in training at the Weather Bureau of Investigation. He learns about different air masses, their movements, and how they interact to cause weather ...

The weather an air mass brings is determined by the region it has come from and the type of surface it has moved over. There are five main air masses which affect the UK as detailed by the map below.