Air Masses & Fronts

Air Masses and Fronts

An air mass is a large body of air with similar temperature and humidity over a wide region. A front is the boundary where two different air masses meet: a warm front rises gently with wide light rain, a cold front undercuts steeply with narrow heavy showers. When a cold front catches a warm front an occluded front forms, and temperature and weather change after passage. Here you can slide front types and compare how warm and cold fronts move air.

What is an Air Mass?

🌬️ A Large Body of Uniform Air

①Air mass: a wide region of air with similar properties

②Stays put long enough to take on local temperature & humidity

③Air masses affecting Korea: Siberian, Okhotsk, North Pacific

Types of Fronts

Front Type0

Compare Fronts

ChartWarm Front vs Cold Front

Category	Warm Front	Cold Front
Movement	Warm air pushes forward	Cold air pushes forward
Slope	Gentle	Steep
Cloud	Stratus (wide)	Cumulus (tall)
Rain	Wide area, light rain	Narrow area, heavy rain
After Passage	Temp↑, clear	Temp↓, clear

Summary

Front

Front = boundary between two different air masses

Warm, cold, occluded, stationary fronts

🎯 Exam Points

①Air mass: uniform-property air over a wide area

②Front: boundary where two air masses meet

③Warm front: gentle slope, wide area, light rain

④Cold front: steep slope, narrow area, heavy showers

⑤Cold front catches up to warm front → occluded front

Examples and Unit Test

Example 1

How do a warm front and a cold front differ in the movement of air, the clouds, and the rain?

At a warm front, warm air rises gently over cold air, so layered (stratus) clouds spread widely and light rain falls for a long time.

At a cold front, cold air pushes sharply under warm air, so heaped (cumulus) clouds tower up and a strong shower falls over a narrow area.

▸ Warm front = gentle rise, stratus, wide light rain / cold front = steep slope, cumulus, narrow strong shower

Which air pushes in decides what the clouds and rain look like.

Example 2

How do temperature and weather change after a cold front passes a region, and how is an occluded front formed?

After a cold front passes, cold air moves in and the temperature drops, and once the strong shower ends the sky clears.

A cold front moves faster than a warm front, so when it catches up with the warm front ahead, the two fronts overlap and form an occluded front.

▸ After a cold front = temperature down and clearing / occluded front = a cold front catches up with and overlaps a warm front

The key to the occluded front is that the faster cold front eventually catches up with the warm front.

Unit Test

Which statement about air masses and fronts is correct?

①After a warm front passes, the temperature drops

②A cold front brings light rain over a wide area for a long time

③A front is the boundary where two air masses of different properties meet

④Stratus clouds develop at a cold front

⑤An occluded front forms when a warm front catches up with a cold front

▸ ③ A front is the boundary where two air masses of different properties meet

After a warm front passes the temperature rises (① wrong), and wide light rain is a feature of a warm front (② wrong).

Cumulus clouds develop at a cold front (④ wrong), and an occluded front forms when a cold front catches up with a warm front (⑤ wrong); a front is the boundary where two air masses meet (③ correct).

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