Question

Which one of the following is the basis of Thomthwaite's classification of climates?
1. Precipitation effectiveness and thermal efficiency
2. World distribution of natural vegetation
3. Distribution of land and waterbodies
4. Movement of air masses

Answer 1

Correct Answer - Option 1 : Precipitation effectiveness and thermal efficiency

Precipitation effectiveness and thermal efficiency are the basis of Thomthwaite's classification of climates.

Thomthwaite's classification of climates:

• Thornthwaite climate classification scheme for describing climates devised in 1931, the full scheme in 1933 and revised in 1948
• Charles Warren Thornthwaite (1889–1963) was an American climatologist which divides climates into groups according to the vegetation characteristic of them.
• His scheme was complex and empirical
• Here he used some factors like precipitation effectiveness, temperature effectiveness, potential evapotranspiration or thermal efficiency index, moisture index, aridity, and humidity indices. 
• He tried to draw an indication by natural vegetation for the climate of a region.
• Here he considered two factors
  • Precipitation effectiveness: (monthly precipitation)/(monthly evaporation)
  • Temperature effectiveness: 

Humidity zones	Vegetation	P/E index
A (wet)	Rainforest	127
B (humid)	Forest	64-127
C (subhumid)	Grassland	32-63
D (semiarid)	Steppe	16-31
E  (arid)	Desert	<16

 

Temperature provinces	T-E index
A’ (tropical)	127
B’ (mesothermal)	64-127
C’ (microthermal)	32-63
D’ (taiga)	16-31
E’ (tundra)	1-15
F’ (frost)	0