Understanding Air Masses & Weather Fronts: Interactions & Impacts, Exercises of Earth, Atmospheric, and Planetary Sciences

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AIR MASSES

FRONTS

AIR MASSES

Types of Air Masses

• Continental Polar, “cold and dry”
  • Originates closer to the Poles over land- locked regions.
• Continental Tropical, “warm and dry”
  • Originates closer to the Tropics over land- locked regions.
• Maritime Polar, “cold and damp”
  • Originates closer to the Poles over water.
• Maritime Tropical, “warm and humid”
  • Originates closer to the Tropics over water.
• Arctic, “very cold”
  • Originates in the very cold land-locked areas

Analyzing Air Masses

• An air mass is most easily identified by

comparing it to other air masses.

• Air masses can be modified with time, most

notably by days of sunshine or lack thereof.

• Fronts are the dividing line between air

masses so understanding air masses, means

understanding where fronts are located.

Fronts are the boundaries between two air masses. Fronts are the basic building blocks of weather systems. Fronts occur where two large air masses collide at the earth's surface. Each air mass has a different temperature associated with it. Fronts are caused by winds moving one air mass away from its birthplace. Fronts

4 different types:

1. Cold front

2. Warm front

3. Stationary

4. Occluded

Air Masses and Fronts

Fronts are classified as to which type of air mass (cold or warm) is replacing the other. A cold front separates the leading edge of a cold air mass displacing a warmer air mass. A warm front is the leading edge of a warmer air mass replacing a colder air mass. If the front is essentially not moving (i.e. the air masses are not moving) it is called a stationary front.

Fronts

1. Cold front

Cold fronts occur when heavy cold air

displaces lighter warm air, pushing it upward.

Cumulus clouds form and usually grow into

snow storms.

Temperatures drop anywhere from 5° to 15°.

Winds become gusty and erratic.

Rain, snow, sleet, and hail can occur with a

cold front.

Cold Front

• Marked on a map with a blue line and blue

triangles pointing towards the warm air.

• Associated with cumulus & cumulonimbus

clouds ahead of the front in the warm air,

producing showers and thunderstorms.

Cold Front

http://www.free-online-private-pilot-ground-school.com/images/cold-front.gif

Cold Front

Warm Front

• Marked on a map by a red line with red semi-

circles pointed towards the cool air (in the

direction the warm air is retreating to.)

• Generally associated with stratus type clouds,

overcast skies, fog, and general rain or snow.

Warm Front

http://www.physicalgeography.net/fundamentals/7r.html

Warm Front

Fronts

3. Stationary

Stationary fronts occur when neither warm nor cold air advances.

The two air masses reach a stalemate.

These type of conditions can last for days, producing nothing but

Altocumulus clouds.

Temperatures remain stagnant and winds are gentle to nil.