ATMO 2301 Class #10: Monday, September 20, 2010

The B Climate TypesThe Oceans

1Monday, September 20, 2010

The B (dry) climate types

• Occupy more area than any other climate group—deficient in precipitation most of year

• Have potential evaporation and transpiration that exceed precipitation

• Generally occur in 2 contexts– Near the subtropical highs– On the leeward or downwind side of mountain

ranges

Monday, September 20, 2010 2

B Climate Subgroups

• There are four: BWh, BWk, BSh, BSk– W is a true desert, extremely dry– S is semi-arid, or steppe

– h is a hot climate– K is a cold (in winter) climate

– Lubbock has a BSk climate

Monday, September 20, 2010 3

Fig. 17-6, p. 477Monday, September 20, 2010 4

Fig. 17-7a, p. 478Monday, September 20, 2010 5

Fig. 17-7b, p. 479Monday, September 20, 2010 6

Table 17-1a, p. 480Monday, September 20, 2010 7

Fig. 17-2, p. 472Monday, September 20, 2010 8

Fig. 17-5, p. 476Monday, September 20, 2010 9

Fig. 17-12, p. 484Monday, September 20, 2010 10

Fig. 17-13, p. 484Monday, September 20, 2010 11

Fig. 17-15, p. 486Monday, September 20, 2010 12

Fig. 17-14, p. 485Monday, September 20, 2010 13

Fig. 17-16, p. 486Monday, September 20, 2010 14

More B Climate facts

• Subtropical deserts extend from roughly 20-30° latitude in large continental regions, often surrounded by mountains

• Xerophytes are plants capable of surviving long periods of drought—cacti, creosote bushes and short-lived plants

• Steppe has characteristic vegetation—short bunch grass, scattered low bushes, sagebrush

Monday, September 20, 2010 15

Introduction to the oceans

Monday, September 20, 2010 16

Interpreting heat fluxes for the oceans

• Positive ocean heat flux– Ocean gains energy– Ocean temperature < air temperature

• Negative ocean heat flux– Ocean loses energy– Ocean temperature > air temperature

• Fluxes are radiative, sensible and latent heating

Monday, September 20, 2010 17

Fig. 8-1, p. 210

Advection of energy by ocean currents

• Advection helps balance the overall energy budget of the earth and atmosphere

• Chapter 2 included only the average for the whole globe

• There is an energy deficit at higher latitudes• There is an energy excess at lower latitudes

Monday, September 20, 2010 19

Fig. 8-2, p. 211

Vertical structure of the oceans

• There are three layers of the ocean• Nearest the surface is the surface zone or

mixed layer of nearly constant temperature• Deepest is the deep zone of slowly decreasing

temperature approaching 0°C• Between the surface layer and the deep zone

is the thermocline, where temperature decreases downward rapidly from the surface layer

Monday, September 20, 2010 21

Fig. 8-3, p. 212

Fig. 8-4, p. 213

Sea Surface Temperatures

• Are actually measured a few feet below the surface

• Are influenced by latitude and ocean currents• Cold ocean currents flow equatorward or in

the west to east direction in middle and high latitudes

• Warm ocean currents flow poleward or in the east/west directions in tropical latitudes

Monday, September 20, 2010 24

Fig. 8-5, p. 213

Directions of ocean currents

• Ocean currents flow in gyres around the various ocean basins

• The gyres flow in an anti-cyclonic direction, clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere

• The gyres form under the influence of the subtropical highs, the deflection of the Coriolis effect, surface friction, and the boundaries of land masses

Monday, September 20, 2010 26

Fig. 8-6, p. 214

The oceans have motions similar to weather systems in the atmosphere

• Front-like features can develop at the boundaries of ocean currents

• Eddies can develop at the boundaries of ocean currents

Monday, September 20, 2010 28

Fig. 8-7, p. 214

Fig. 8-8, p. 215

Fig. 8-9, p. 215

Fig. 8-10, p. 216

Fig. 8-11, p. 217

Fig. 8-12, p. 218

Fig. 8-13, p. 218

Fig. 8-14, p. 219

Table 8-1, p. 220

Fig. 8-15, p. 221

Fig. 8-16, p. 221

Fig. 8-17, p. 222