ATMO 2301 Class #10: Monday,
September 20, 2010
The B Climate Types
The Oceans
Monday, September 20, 2010
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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
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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
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Fig. 17-6, p. 477
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Fig. 17-7a, p. 478
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Fig. 17-7b, p. 479
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Table 17-1a, p. 480
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Fig. 17-2, p. 472
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Fig. 17-5, p. 476
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Fig. 17-12, p. 484
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Fig. 17-13, p. 484
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Fig. 17-15, p. 486
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Fig. 17-14, p. 485
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Fig. 17-16, p. 486
More B Climate facts
• Subtropical deserts extend from roughly 2030° 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
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Introduction to the oceans
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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
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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
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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
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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
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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
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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
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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