World Climate Regimes

Geog403

Climate classifications

• Empirical Classification: based on the results (temperature, precipitation, vegetation, etc.)

Examples: Köppen’s classification; Thornthwaite’s classification

• Genetic Classification: based on the causes (air masses, atmospheric circulation; geographical location, etc.)

Examples: Strahler and Strahler; Mather

Köppen Climate Classification (based on vegetation distribution)

A: Equatorial (tropical) Climate

Af-humid, no dry season (tropical rainforest)

Am- short dry season (monsoon)

Aw-wet and dry seasons (Savanna)

Rainforest

Monson

Tropical Savanna

Koppen- DesertB: Dry climateBs: semiaridBw: arid

Low-Latitude Hot

Desert

Mid-Latitude Cold Desert

Low-Latitude Hot Steppe

Köppen-Mesothermal

C: Humid Temperate climate

Cf-no dry seasonCw-dry winter

(subtropical monsoon; interior)

Cs-dry summer (mediterranean)

Humid Subtropical Hot-Summer

Humid Subtropical Hot-Summer

Humid Subtropical Winter-Dry

Figure 10.12

Marine West Coast

Marine West Coast

Mediterranean Climates

KÖppen-MicrothermalD: Humid Cold

ClimateDf-no dry seasonDw-dry winter

(interior, high latitude, shorter, cooler summer)

Humid Continental

Hot-Summer Climates

Humid Continental Mild-Summer Climates

Subarctic Cool Summer Climates

Extreme Subarctic Cold Winter

Polar and Highland climates

E: Cold polar climate (too cold to support vegetation)

F: High Land climate

Genetic classificationAir masses:cP: continental polar (cold

and dry; source: northern Canada, Siberia)

mP: maritime polar (cool and moist; Source: northern Pacific and Atlantic Ocean)

cT: continental tropical (hot and dry; source: desert)

mT: maritime tropical (warm and moist; tropical oceans)

mT mTcT

cPmP mP

General Circulation patterns

ITCZ: inter-tropical convergence zone (wet)

NE trade windSubtropical high

(dry)WesterliesPolar front (wet)NE wind

Potential evapotranspiration

Defined by ThornwaiteThe demand of water by a continuous

vegetation cover with uniform height that never lacks of water

It is determined by the latitude (solar radiation) and time of the year (solar angle) only. (or represents the air temperature)

Genetic Climate regimes

Low latitudes (30ºS-30ºN)1. Wet equatorial 10ºS-10ºN, warm

to hot, abundant rain.2. Tropical wet and dry: 5º-25º N or

S, warm to hot, distinct wet and dry seasons (savanna)

3. Trade wind littoral (monsoon and trade wind), east coast 10º-25º N or S.

4. Tropical desert/steppe: 15º-35ºN or S, world’s hottest desert

5. West coast desert: 15º-30ºN or S, west coast.

PEP

J D

PEP

PE

P

J

1 & 3

2

4 & 5

Middle latitudes (30º-60ºN or S)6. Humid subtropical: 25º-40ºN or S

eastern continent, hot and humid summer, mild winters, ample rain year around.

7. Mediterranean: 30º-40ºN or S west coast, hot and dry summer, and rainy winters

8. Maritime west coat (40º-60ºN or S), warm summers and cool winters with more rain in winter.

9. Middle-latitude desert and steppe: 35º-60ºN or S interior, not as hot and dry.

10. Humid continental: 35º-60ºN or S, cold winters and warm summers, ample precipitation through out the year.

P

PE

PE

P

PPE

6

7

8

PEP

9

PE

P10

High latitudes (60º-90ºN)• Continental subarctic: 50º-70ºN

interior, short, cool summers and long bitterly cold winters.

• Marine subarctic: 50º-60º west coast, cool summers, mild winters.

• Tundra: 50ºN, long severe winters (proximity to Arctic ocean).

• Ice cap: bitterly cold temperatures, temperature remains below freezing in summer.

60N

30N

Tropical wet

West C

oat D

esert Tropical wet & dry

Desert and Steppe

Trade wind littoral

MediterraneanHumid tropicalDesert

Humid continentalMarine west coast

Marine subarctic

Continental subarctic

Tundra

Ice cap

0N

90N