Earth Science
Chapter 18
Section 2
A. Classifying Climates:
Scientists classify climates according to two major factors.
1. Temperature
2. Precipitation
There are five main climate regions:
1. Tropical rainy
2. Dry
3. Temperate marine
4. Temperate continental
5. Polar
1. Tropical rainy:
Temperature always 18 C (64 F) or above.
Subdivisions
a. Tropical wet:
Always hot and humid, with heavy rainfall
(at least 6 cm/year) all year round.
b. Tropical wet and dry:
Always hot, with alternating wet and dry
seasons; heavy rainfall in the wet season.
2. Dry:
Occurs wherever potential evaporation is greater than
precipitation. May be in hot or cold regions.
Subdivisions
a. Arid:
Desert, with little precipitation, usually less
than 25 cm/year.
b. Semiarid:
Dry but receives about 25 to 50 cm of
precipitation/year.
3. Temperate marine:
Average temperature 10 C (50 F) or above in the warmest
month, between –3 C (26 F) and 18 C (64 F) in the coldest
month.
Subdivisions
a. Mediterranean:
Warm, dry summers and rainy winters.
b. Humid subtropical:
Hot summers and cool winters
c. Marine west coast:
Mild winters and cool summers, with
moderate precipitation year round.
4. Temperate continental:
Average temperature 10 C (50 F) or above in the warmest
month, -3 C (26 F) or below in the coldest month.
Subdivisions
a. Humid continental:
Hot, humid summers and cold winters, with
moderate precipitation year round.
b. Subarctic:
Short, cool summers and long, cold winters.
Light precipitation, mainly in summer.
5. Polar:
Average temperature below 10 C (50 F) in the warmest
month.
Subdivisions
a. Tundra:
Always cold with a short, cool summer,
warmest temperature about 10 C (50 F).
b. Ice Cap:
Always cold, average temperature at or
below 0 C (32 F).
6. Highlands:
Generally cooler and wetter than nearby lowlands,
temperature decreasing with altitude.