1 Air masses, Fronts, & Cyclones Extratropical Cyclone –Cyclone not in the tropics –Also known as Frontal Lows Frontal Cyclones Wave Cyclones Frontal Waves Ch 8 Sec A

2 Air masses, Fronts, & Cyclones Air Masses: Named by where they come from: From over land or over water –c for Continental: From Over Land: Dry –M for Marine: From over the ocean: Moist From a geographic region of the Earth: –Arctic: very cold –Polar: cold –Tropical: Warm Ch 8 Sec A

3 Air masses, Fronts, & Cyclones These air masses are abbreviated: A, P, T, m, c, mP, mT, cT, cP, etc mP is cold and moist mT is warm and moist cP is cold and Dry A is very cold and dry. cT can be hot and dry: Toast w/o a Toaster or warm and moist Ch 8 Sec A

4 Airmasses, Fronts, & Cyclones These Ch 8 Sec A

5 Air masses, Fronts, & Cyclones Front: Represents the movement of an Air Mass of uniform characteristics –Warm Front: Leading Edge of a Warm air mass –Cold Front: Leading Edge of a Cold air mass –Stationary Front: Cold air mass touching a warm air mass with little movement –Occluded front: Cold front overtaking a warm front overtaking a cool air mass. Ch 8 Sec A

6 Airmasses, Fronts, & Cyclones Front Ch 8 Sec A

7 Air masses, Fronts, & Cyclones Frontal Slopes: –Cold Air masses move under Warm air masses pushing them up. The moisture in the Warm air mass condenses and produces precipitation. –This upward push can span 100 miles on the ground and up to a mile or more vertically. Ch 8 Sec A

8 Airmasses, Fronts, & Cyclones Frontal Slopes: –Cold Air masses move under Warm air masses pushing them up. The moisture in the Warm air mass condenses and produces precipitation. –This upward push can span 100 miles on the ground and up to a mile or more vertically. Ch 8 Sec A

9 Air masses, Fronts, & Cyclones Frontal Zones: –Are not sharp lines but extend for tens or hundreds of miles –A cold front pushes the Warm air up faster than a warm front rises over a cold air mass Ch 8 Sec A

10 Airmasses, Fronts, & Cyclones Frontal Ch 8 Sec A

11 Airmasses, Fronts, & Cyclones Frontal Ch 8 Sec A Which is more abrupt?

12 Airmasses, Fronts, & Cyclones Frontal Ch 8 Sec A Cold Front: Heavy Precipitation: Storms Warm Front: Mild Precipitation

13 Air masses, Fronts, & Cyclones Extratropical Cyclone Structure and Development –Depends on Climate The mT flow from the Gulf of Mexico –Geographic features The Vertical flows produced by Mountain Chains: The Rockies –Surface Conditions Warm Moist Surface Conditions Ch 8 Sec A

14 Air masses, Fronts, & Cyclones Extratropical Cyclone Structure and Development –1. As a front approaches: Pressure falls As it passes the pressure rises: cold fronts –2. The sharp change in pressure gradient across a front, corresponds to a sharp wind shift and possible cyclonic wind shear Ch 8 Sec A

15 Airmasses, Fronts, & Cyclones Extratropical Cyclone Structure and Development Ch 8 Sec A

16 Air masses, Fronts, & Cyclones Extratropical Cyclone Structure and Development A frontal low has a high probability of developing when an upper level short wave trough moves to within 300 mi. of a surface stationary front. The east side of an upper level short wave trough is the bad weather side. Ch 8 Sec A

17 Airmasses, Fronts, & Cyclones Extratropical Cyclone Structure and Development Ch 8 Sec A

18 Airmasses, Fronts, & Cyclones Extratropical Cyclone Structure and Development Ch 8 Sec A

19 Airmasses, Fronts, & Cyclones Extratropical Cyclone Structure and Development Ch 8 Sec A

20 Air masses, Fronts, & Cyclones Weather Guidelines –Approaching Warm Front: light steady precipitation with stratiform clouds –These warm fronts can produce fog. –When the air behind a cold front is moist and unstable, it is characterized by CU clouds –A high pressure ridge or area is characterized by downward air movement and SKC Ch 8 Sec A

21 Airmasses, Fronts, & Cyclones Weather Ch 8 Sec A

22 Airmasses, Fronts, & Cyclones Weather Ch 8 Sec A A Jet Stream Loop

23 Airmasses, Fronts, & Cyclones Weather Ch 8 Sec A A Jet Stream Loop

24 Airmasses, Fronts, & Cyclones Weather Ch 8 Sec A A Jet Stream Loop

25 Air masses, Fronts, & Cyclones Tropical Cyclones and Hurricanes: a mesoscale cyclonic circulation that develops in the tropical easterlies. They are classified by their intensities with 1 being the least intense and 5 being the most intense Ch 8 Sec B

26 Airmasses, Fronts, & Cyclones Tropical Cyclones and Hurricanes: Ch 8 Sec B

27 Airmasses, Fronts, & Cyclones Tropical Cyclones and Hurricanes: Ch 8 Sec B

28 Air masses, Fronts, & Cyclones Tropical Cyclones and Hurricanes: Structure –Rain Bands: Spiral Arms –Eye: High Pressure and clear of clouds –Eye Wall: Strongest Winds Ch 8 Sec B

29 Airmasses, Fronts, & Cyclones Tropical Cyclones Ch 8 Sec B

30 Airmasses, Fronts, & Cyclones Tropical Cyclones Ch 8 Sec B