Environmental Science 102
Climate Classification and Climates


Air Masses Classification

Large bodies of air that form in a Source Region (origin area).
Based on 2 aspects

1) Latitude: indicates the general temperature conditions
3 class system
A (Arctic/Antarctic) – high latitudes, coldest air masses
P (Polar) – Mid- to high latitudes, cold air masses
T (Tropical/Equatorial) – Low latitudes, warm air masses

2) Source Area Surface: Indicates the humidity conditions
m (maritime) – oceans, seas or gulfs
c (continental) – large land masses

2 letter scheme, combining: – small case Source designation – upper case Latitude designation.
Examples: mA, cA, mP, cP, mT, cT

Climate

Climate is the long term average atmospheric conditions for a region.
Typically based on:
Global Climate is the long term average weather for the entire planet.

Temperature

Precipitation

Climographs

Displays average temperature and precipitation for a specific location Should contain the following information: Location name Longitude and latitude Elevation Temperature line graph Precipitation bar graph

Climate Classification

5 Major Groups of 13 Climate Types based on Temperature and Precipitation
Wladimir Köppen classification developed in 1900

Climate Classification Chart

Group A – Humid Tropical Climates

Winterless climates
All months have a mean temperature above 18°C
ITC, Trade winds, Subtropical High Pressure Belt
cT, mT, cE, mE air masses

Group B - Dry Climates

Climates where evaporation exceeds precipitation; constant deficiency of water
cP, mP, cT, mT air masses
Subtropical High Pressure Belt, Polar Front, Wave Cyclones, Prevailing Westerlies

Group C – Humid Mid-Latitude Climates

Mild winters; average temperature of coldest month is below 18°C, but above -3°C.
cP, mP, cT, mT air masses
Subtropical High Pressure Belt, Polar Front, Wave Cyclones, Prevailing Westerlies

Group D - Humid Mid-Latitude Climates

Severe winters; average temperature of coldest month is below -3°C, and the warmest monthly mean is above 10°C.
cA, mA, cP, mP, cT, mT air masses
Polar Front, Wave Cyclones, Prevailing Westerlies

Group E – Polar Climates

Summerless climates; average temperature of the warmest month is below 10°C.
cA, mA, cP, mP air masses
Polar Front, Wave Cyclones, Polar Easterlies

H - Highland Climates

Occurs in higher elevation terrains
No common latitude
Temperature is generally lower than neighboring climates but varies widely
Precipitation can be very low to very high
Orographic precipitation / Rain shadow effects are common
Many local variations in climate - Microclimates

Microclimates

Small variations in the climate due to small changes in:
Elevation
Insolation
Temperature
Wind direction
Compass orientation of the slope.

Other Climate Classifications

Thornthwaite Classification- developed in 1931- 32 climate types: 5 major humidity provinces- rainforest, forest, grassland, steppe, desert
Kendrew Classification- Based on continental geographic regions