Simplified: Koppen Method of Climate Classification

The three methods of classification of climate by Koppen, Trewartha and Thornthwaite are very frequently asked in the UPSC Geography Optional Paper 1. I had made notes for such high frequency topics. This topic should be studied comparatively to remember the three methods. I will list out Koppen’s method of classification and compare Trewartha and Thornthwaite with it.

Koppen’s Classification of Climate

• It is empirical (based on observation) and not genetic (based on origin)
• Based on Candolle’s vegetation Zones
• Average annual precipitation and monthly temperature & precipitation values are the criteria

5 Major Types and their sub-types

1. A: average monthly temperature always above 18 degrees. Tropical region
2. B: Moisture/ Rain deficit. Evaporation exceeds precipitation
3. C: Humid, mesothermal, mid-latitude, coldest month between 3-13 degrees
4. D: Humid microthermal, coldest month 3 degree or below. Warmest month 10 degree or above
5. E: Polar climate. Warmest month <10 degree

Other letter code

These codes are fairly intuitive. If you learn them, it will be easier to remember the entire classification.

1. f: rain throughout the year
2. w: winter dry
3. m: monsoon
4. s: summer dry
5. h: hot
6. k: cold

Detailed Koppen Classification of Climates

• Type A
  • Af: Equitorial rainforest (A= tropical, f= always rain; easy peasy!)
  • Aw: Savanna type (winter dry tropical region)
  • Am: Monsoon type (short dry season, adequate rainfall)
  • As: Summer Dry (rare)
• Type B
  • BS: Steppe Type semi-arid (less
    • BSh: avg. annual temperature >18 degrees (tropical Steppe)
    • BSk: avg. annual temperature <18 degrees (mid-latitude Steppe)
  • BW: dry desert climate (more extreme)
    • BWh:  avg. annual temperature >18 degrees
    • BWk: avg. annual temperature <18 degrees
• Type C
  • Cf: Western European Type
  • Cs: Dry summer, 3x precipitation in winter. Mediterranean Climate
  • Cw: Dry Winter. 10x ppt. in summers. China type climate
• Type D
  • Df: no dry season
  • Dw: winter dry season
• Type E
  • ET: Tundra type, 0-10 degrees
  • EF: Permafrost zone, below 0 degree

Pros of Koppen Classification

1. Quantitative: easier to understand and measure
2. Co-incides with vegetation pattern
3. gave importance to effective precipitation (evapotranspiration)

Cons of Koppen Classification

1. Difficult to memorize (not anymore 🙂 )
2. Too much emphasis on average values
3. Ignored precipitation intensity, cloud cover, daily temperature variations, number of rainy days etc.
4. Ignored role of air masses
5. Was not a genetic classification