Climatic zones

050-08-01Pablo Asensio Martínez2026-04-013 min

Climatology studies long-term weather patterns. One of the most widely used classifications is the Köppen system, which divides the world's climates into five main groups based on temperature and precipitation.

Köppen Climate Classification Map Köppen-Geiger Climate Classification global map.

Köppen Climate Classification

Class A: Tropical Rain Climate

  • Location: 0° - 10° N/S (Equatorial regions).
  • Characteristics:
    • Mean temperature of the coldest month > 18°C.
    • Mean monthly precipitation > 60 mm.
    • No dry season.
    • High relative humidity (~80%).
    • High freezing level (~15,000 ft).
  • Examples: Amazon Rainforest (Brazil), Congo Basin.

Class B: Dry Climate

  • Location: 20° - 35° N/S (Subtropical high-pressure belts).
  • Characteristics:
    • Evaporation and transpiration exceed precipitation.
    • No permanent watercourses.
    • Influenced by subtropical anticyclones.
  • Examples: Sahara Desert, Kalahari Desert.

Class C: Mid-latitude / Warm Temperate Climate

  • Location: 40° - 70° N/S.
  • Characteristics:
    • Defined summer and winter seasons.
    • Mean temperature of the coldest month between -3°C and 18°C.
  • Examples: Northwest Europe, New Zealand, Southeast USA.

Class D: Sub-arctic or Boreal Climate

  • Location: 50°N - 70°N (Northern Hemisphere only, large landmasses).
  • Characteristics:
    • Mean temperature of the warmest month > 10°C.
    • Mean temperature of the coldest month < -3°C.
  • Examples: Northern Eurasia, Canada.

Class E: Polar or Snow Climate

  • Location: > 70° N/S.
  • Characteristics:
    • Mean temperature of the warmest month < 10°C.
    • Dry and anticyclonic winters.
    • Permafrost soil.
  • Examples: Greenland, Antarctica.

Transitional Climatic Zones

Between the main zones, there are transition areas with mixed characteristics:

Tropical Transition Climate (Savanna)

  • Location: 10° - 20° N/S.
  • Characteristics:
    • Winter: Warm and dry (Trade Winds).
    • Summer: Warm and wet (Equatorial rains).
  • Examples: Northwest Africa, Ghana.

Temperate Transition Climate (Mediterranean)

  • Location: 35° - 40° N/S.
  • Characteristics:
    • Winter: Cool and wet (frontal depressions).
    • Summer: Hot and dry (subtropical anticyclonic influence).
  • Examples: Mediterranean Basin, California, Central Chile.

Global Circulation and Winds

Global climate is determined by latitude, air masses, heat exchange from ocean currents, and mountain barriers.

Trade Winds

Persistent winds blowing from the subtropical high-pressure belts towards the Intertropical Convergence Zone (ITCZ).

  • Northern Hemisphere: Northeast Trades (NE Trades).
  • Southern Hemisphere: Southeast Trades (SE Trades).
  • In summer, over the oceans, they usually bring fair weather with cumulus or stratocumulus (Trade Wind inversion).

Monsoons

Seasonal wind systems caused by thermal differences between large landmasses and the ocean.

  1. NE Monsoon (Asian Winter):

    • Blows from the Siberian High.
    • Cool and dry air.
    • Brings clear weather to India, Burma, and Thailand.

  2. SW Monsoon (Asian Summer):

    • Produced by SE Trades crossing the equator and turning SW.
    • Warm and very moist air.
    • Brings clouds of vertical development (Cu, Cb), heavy thunderstorms, and severe turbulence.
    • Affects India, Sri Lanka, Burma, and the West African coast.

ITCZ Movement

The Intertropical Convergence Zone shifts with the sun:

  • NH Summer: Shifts North.
  • NH Winter: Shifts South. This movement causes the seasonal displacement of circulation cells and rain belts.