🌬 AIR MASSES: GIANT BODIES OF AIR
PAGE 1 OF 5, WHAT IS AN AIR MASS?
ONE BIG BREATH
A GIANT SLAB OF AIR WITH ONE MOOD
Picture the sky as a stack of huge invisible blankets. An air mass is one of those blankets: a very large body of air, often hundreds or thousands of kilometres across, that shares nearly the same temperature and humidity from top to bottom. It is not a cloud or a storm by itself. It is the background air that clouds and storms grow inside. When that air sits over the same region for days, it slowly picks up the character of the surface below. Warm and wet over an ocean. Cold and dry over a snowy plain. Later, wind pushes the whole slab to a new place, and your local weather can change fast.
📏 HOW BIG?
Air masses can be larger than many countries. Forecasters track them on weather maps like moving coloured patches.
HUGE!
UNIFORM
🌡 Inside one air mass, temperature and moisture stay fairly even over a wide area for many hours or days.
☀ That sameness is why a clear, calm spell can last until a new air mass arrives from somewhere else.
☀ That sameness is why a clear, calm spell can last until a new air mass arrives from somewhere else.
NOT MIXED YET
🧊 A cold air mass feels crisp and dry. A warm, moist one feels sticky even before rain starts.
🔄 The big weather flip often happens at the edge where two different masses touch, not deep inside one mass.
🔄 The big weather flip often happens at the edge where two different masses touch, not deep inside one mass.