Meteorology and Climate Change

Subsection 11.2.1 General Scheme

The Koppen-Geiger classification scheme was first developed in the late 19th century to describe global climates. It is based upon five main climate groups (A-E), based primarily upon temperature and precipitation patterns throughout the year. These generally correlate with global circulation patterns and latitudinal regions of convergence and divergence:

• First letter indicates global conditions

  • A = Tropical humid

  • B = Dry

  • C = Moist subtropical and midlatitude

  • D = Severe midlatitude

  • E = Polar

• Second letter refers to whether and when a dry season occurs

  • f = no dry season

  • w = winter dry season

  • s = summer dry season

  • m = monsoonal

• Third letter denotes temperature differences

  • h = hot

  • k = cold

  • a = hot summer

  • b = warm summer

  • c = cold summer

  • d = very cold winter

• Dominant climate over land is arid B (about 30%) followed by cold D (about 25%) and tropical A (19%)

Subsection 11.2.2 Specific Groups

• Group A is subdivided into 3 subgroups

  • Af = tropical rainforest

  • Am = tropical monsoon

  • Aw = tropical savannah

• Group B is subdivided into 4 subgroups

  • BWh = subtropical desert

  • BWk = midlatitude dry desert

  • BSh = subtropical steppe

  • BSk = midlatitude steppe

• Group C is subdivided into 9 subgroups

  • Csa = Mediterranean, dry hot summer

  • Csb = Mediterranean, dry warm summer

  • Csc = Mediterranean, dry cold summer

  • Cwa = humid subtropical, dry winter, hot summer

  • Cwb = subtropical highland, dry winter, warm summer

  • Cwc = subtropical highland, dry winter, cold summer

  • Cfa = humid subtropical, hot summer

  • Cfb = marine west coast, warm summer

  • Cfc = marine west coast, cool summer

• Group D is subdivided into 12 subgroups

  • Dsa = humid continental, dry hot summer

  • Dsb = humid continental, dry warm summer

  • Dsc = subarctic/boreal, dry cool summer

  • Dsd = subarctic/boreal, dry summer, very cold winter

  • Dwa = humid continental, dry winter, hot summer

  • Dwb = humid continental, dry winter, warm summer

  • Dwc = subarctic/boreal, dry cold winter, cool summer

  • Dwd = subarctic/boreal, extremely cold dry winter

  • Dfa = humid continental, no dry season, hot summer

  • Dfb = humid continental, no dry season, warm summer

  • Dfc = subarctic/boreal, no dry season, cold summer

  • Dfd = subarctic/boreal, no dry season, extremely cold winter

• Group E is subdivided into 2 subgroups

  • EF = polar frost (permanent ice cover)

  • ET = polar tundra