What Are Air Masses And Fronts?
Air masses are huge bodies of air with fairly uniform temperature and humidity, shaped by where they formed. Fronts are the narrow boundaries where different air masses meet. Because denser air forces lighter air upward along those boundaries, fronts are where much of our clouds, precipitation and severe weather develop.
The United States is a meeting ground. Cold air from Canada, steamy air from the Gulf and dry air from the desert all collide over us, and the edges are where the weather happens. This unit covers who those air masses are and what happens when they bump into each other.
What You’ll Learn
- What an air mass is and how source regions shape it
- The five major North American air masses and their codes
- How to use the dew point to tell which air mass you are in
- How cold fronts and warm fronts differ in slope, speed, clouds and weather
- How a midlatitude storm grows and occludes in the Norwegian Cyclone Model
- Why stationary fronts flood and drylines spark supercells
- How outflow boundaries from thunderstorms trigger new storms
Lessons In This Unit
- 4.1Air Masses And Where They Come FromAn air mass is a huge body of air, often more than 1,000 miles across, with fairly uniform temperature and humidity at each height. It takes on those traits by sitting over one...Beginner · 9 min
- 4.2Cold Fronts And Warm FrontsA cold front is advancing cold air that wedges under warm air and lifts it sharply, bringing a narrow band of showers or storms, then cooler, drier air. A warm front is...Intermediate · 10 min
- 4.3Occluded Fronts, Stationary Fronts And DrylinesAn occluded front forms when a faster cold front catches up with a warm front and lifts the warm air off the ground. It is drawn as a purple line with triangles and half...Intermediate · 11 min
Questions People Ask
What is a front in weather?
A narrow boundary between air masses of different density, usually marked by changes in temperature, dew point, wind direction and pressure.
What air mass brings humid weather to the eastern US?
Maritime tropical air from the Gulf of Mexico, the Caribbean and the subtropical Atlantic.
Why are fronts associated with storms?
Warmer, less dense air is forced upward along the boundary, and rising air cools to form clouds, precipitation and sometimes thunderstorms.
Once you can spot the boundaries, you will start seeing storms coming before the radar does. — Jen
