NATS 101 Lecture 23 Fronts

Review

	Air Masses
	Large regions with ÒuniformÓ temperature and moisture distributions and distinctive weather
	Classified by Source Region
	Continental (c) or Maritime (m)
	Polar (P) or Tropical (T)
	Source Regions
	Big in area (>1600 km by 1600 km)
	Dominated by light winds (long resident times)

Air Mass Characteristics

Air Mass Source Regions

Weather Map with Air Masses, Fronts, Extratropical Cyclone

Extratropical Cyclones and Fronts

	In mid-latitudes, significant weather is often associated with a particular type of storm: Extratropical Cyclone
	Cyclone denotes the circulation around a low pressure center
	The energy for extratropical cyclones comes from horizontal temperature contrasts

Extratropical Cyclones and Fronts

	ET cyclones often form on a boundary between a warm and cold air mass, associated with the jet stream
	They tend to focus temperature contrasts along frontal zones, bands of very rapid horizontal temperature changes

Extratropical Cyclones and Fronts

	Strongest temperature gradients occur at warm edge of frontal zone, called a front
	There are four types of fronts Classified by their movement     Each has its own symbol, color scheme
	Cold, Warm, Stationary, Occluded

Frontal Types

Frontal Types

Frontal Types

Frontal Types

Slide 13

Cross-Section: Cold Front

Typical Cold Front Weather

Slide 16

Cross-Section: Warm Front

Typical Warm Front Weather

Occluded Fronts Cold-Warm Hybrid

Typical Occluded Front Weather

Summary Fronts

	ET cyclones tend to focus temperature contrasts along frontal zones
	Strongest temperature gradients occur at warm edge of frontal zone, called a front
	Fronts classified by movement, each has own symbol and characteristic weather
	Cold, Warm, Stationary, Occluded

Summary: Frontal Weather

Summary: Frontal Weather

Assignment for Next Lecture

	Topic - Extratropical Cyclone Formation
	Reading - Ahrens pg 219-228
	Problems - 8.14, 8.15, 8.17