Class #20: Friday, October 20, 2010

Class #20: Friday, October 20, 2010

The C and D Climate Types

Friday, October 15, 2010 1

The C climate types: moist, subtropical mid-latitude climates

• General characteristics: humid with mild winters (average temperature between 27°F and 64°F); distinct summer and winter seasons, ample precipitation

• Extent: on the eastern and western regions of most continents, from about 25° to 40° latitude

• Major types: humid subtropical (Cfa), marine (Cfb), and dry-summer subtropical or Mediterranean (Csa, Csb)


Categorization of C climates

• C Moist with mild winters– w dry winters– s dry summers– f wet all seasons (no dry season)• a summers long and hot• b summers long and cool• c summers short and cool

• See table on page 480 for details


Cfa: The humid subtropical climate

• Found principally along the east coasts of continents 25° – 40° latitude; Southeastern section of the US, eastern China, and southern Japan. In SH, southeastern SA, Southeastern coasts of Africa and Australia

• Hot muggy summers: under the influence of the western side of subtropical highs, where maritime tropical air flows poleward



• Upper-level ridges produce devastating heat waves

• High temperatures, dew points make summer weather more uncomfortable than the tropics

• Winter weather can be quite changeable• Little snow• Adequate and well-distributed precipitation

through the year



• Summer thunderstorms are common• Tropical cyclones contribute to rainfall total in

the US and China• Winter precipitation in mid-latitude cyclones• Vegetation: in southeast US, thick pine forest

mixed with oak at higher latitudes• Example: Mobile, Alabama


Fig. 17-17, p. 488

Cfb: West coast marine, or marine climate

• Along the west coast of most continents, from latitude 40° to about 60°.

• Dominated by prevailing winds from the ocean that moderate the climate (warmer winters, cooler summers) compared to farther inland. Summers are quite cool. If short, Cfc.

• Limited in horizontal extent by coastal mountains



• In western Europe, Cfb extends well inland• For much of the year, low clouds, fog, drizzle• Adequate precipitation in all months, from mP

air masses, is light or moderate• Mountains enhance precipitation• Along NW coast of NA, less rain in summer,

with northward migration of the subtropical high



• Characterized by a low annual temperature range for such high latitudes

• Frequent precipitation and overcast skies act to minimize daily variation in temperature

• Dense forest of Douglas fir where precipitation is heavy

• Example: Port Hardy, Vancouver Island, Canada


Fig. 17-18, p. 488

Csa,b Dry-summer subtropical, or Mediterranean climate

• On west coasts south of the Cfb climates• On the shores of the Mediterranean Sea• Summer dryness more pronounced than the

Cfb climates• Mild (Csb) to hot (Csa) dry summers• Dryness due to the sinking air in the

subtropical highs and their diversion of storms poleward in summer



• During winter, subtropical highs move south, and extratropical cyclones provide rain

• Typically, mild wet winters

• Csa: interior Mediterranean (Sacramento)• Csb: coastal Mediterranean (San Francisco)



• Csa– Summers are hot– Winters a little colder than Csb– Wider annual variation in temperature

• Csb– Upwelling keeps air cool all summer– Often shrouded in low cloud and fog– Small annual range in temperature


Fig. 17-19, p. 489


• Snow is rare• Land supports chaparral, a scrubby type of

low-growing woody plants and trees• Mediterranean Sea: summers not so dry as

NA (far from subtropical high); also warmer (no upwelling)


Fig. 17-20, p. 490

Cw climate type

• Winter dry season• Associated with the winter monsoon in Asia• Prevailing winds around continental High• Northern India and portions of China• In lower latitudes, higher altitudes keep them

from being tropical because they are too cool


Fig. 17-21, p. 491

Table 1, p. 492

Fig. 3, p. 492

Fig. 4, p. 493

Fig. 17-22, p. 494

Fig. 17-23, p. 495

Fig. 17-24, p. 495

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Class #20: Friday, October 20, 2010

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