Air Masses and Fronts Air Mass n Large
- Slides: 34
Air Masses and Fronts
Air Mass n Large unit of air in which temperature and moisture conditions are uniform at a given altitude. n Moves separately from surroundings n temperature and moisture conditions determined by SOURCE REGION of air mass
Properties of source region: n Moisture: continental “c”, maritime “m” n determined by underlying surface (ocean or land) n n Thermal: Polar “P”, Tropical “T”, Equatorial “E”, Arctic “A” n determined by latitude n
n Combination: n c. P n m. T n c. A n m. E (or c. AA)
Air Masses that affect U. S. weather: n c. P: n c. A: n m. P, Pacific: cool, moist air cold dry air from Canada; High pressure from Arctic Ocean region; extremely cold m. P, Atlantic: cool, moist, but often no effect due to prevailing wind n m. T: from Gulf and Caribbean: hot, wet air n m. T, Pacific: slightly cooler and drier n c. T: hot dry air; persistent
Air masses… n modify the local weather of places they invade n are modified by the places they invade
n Front: the boundary between two unlike air masses n n unlike in temperature, moisture, or both named according to motion of the cold air
Cold front
Cold front Cold air is advancing n 20 mph n leading edge is steep (1: 40) n unstable along front: warm air rises over cold air rapidly n short duration (hours) n heavy precipitation in narrow band behind front n followed by clear weather n Symbol : n
Cold front animation
Warm Front
Warm front Cold air is retreating n 10 mph n leading edge is not steep (1: 150) n warm air gently climbs over cold air (not as unstable as cold front) n duration (days) n stratus and nimbostratus clouds n light precipitation in wide band ahead of front n Symbol: n
Warm front animation
Stationary front n no movement of air masses n precipitation at the front: not much on warm side n stratus clouds and steady precipitation on cold side n n Weather map symbol :
Occluded front occurs when a cold front overtakes a warm front
n In occluded fronts, warm air wedge is lifted off of ground; clouds are high, then they lower and thicken into middle and low clouds; precipitation occurs n Symbol : n Occluded fronts are associated with storms called “wave cyclones”
Cyclogenesis: the development of a wave cyclone n Wave cyclone: migrating center of low pressure n causes storms in the midlatitudes n Form along polar front n
Favorable conditions: n n n “Trough” of low pressure between two Highs along polar front converging air unstable
1. Early stage surface convergence; lifting around Low
2. Open Stage
3. Occluded Stage
4. Dissolving Stage warm air mass completely cut off from ground; no more uplift
- What are middle-latitude cyclones?
- Air mass
- Air masses in north america
- Two cold air masses converge on a warm air mass
- Cold front air movement
- Air masses & frontswhat is an air mass?
- Maritime tropical air mass symbol
- Air masses & frontswhat is an air mass?
- Air masses & frontswhat is an air mass?
- Stationary front
- Why are cold fronts steeper than warm fronts
- An air mass is created when a large body of air
- Cold air mass overtakes warm air mass
- Air mass vocabulary
- Large scale rotating air mass
- Front
- Air fronts
- Air masses and their characteristics
- Area of low pressure where air masses meet and rise
- Air masses form in the tropics and have low pressure
- Meteorological symbols for four types of fronts
- Jet stream map
- How to draw warm and cold fronts
- Importance of air masses
- Types of air masses
- Lake effect side
- Continental polar symbol
- Air mass map
- Warm hall
- Weather depression
- What are the five types of air masses?
- Continental arctic air mass symbol
- Air masses
- Air masses
- Occluded front