Definition of types and subtypes as defined by the Köppen-Trewartha climate classification according to Trewartha and Horn (1980). T denotes mean annual temperature (°C), Pmean is the mean annual rainfall (cm), R is Patton’s precipitation threshold. Tcold (Twarm) stands for monthly mean air temperature of the coldest (warmest) month
| Type | Criteria | Subtype | Rainfall regime |
|---|---|---|---|
| A |
Tcold > 18 °C Pmean above value given in B |
Ar | 10 to 12 months wet; 0 to 2 months dry |
| Aw | winter (low-sun period) dry; more than 2 months dry | ||
| As | summer (high-sun period) dry; rare in A climates | ||
| B | Pmean < R (R = 2.3T - 0.64 Pw +41) | BS | R/2 < Pmean < R |
| BW | Pmean < R/2 | ||
| C | 8-12 months with T > 10 °C | Cs | summer dry; at least three times as much rain in winter half year as in summer half year; driest summer month less than 3 cm of precipitation; annual precipitation total under 89 cm |
| Cw | winter dry; at least ten times as much rain in summer half year as in winter half year | ||
| Cf | no dry season; difference between driest and wettest month less than required for s and w; driest month of summer more than 3 cm | ||
| D | 4-7 months with T > 10 °C | Do | Tcold > 0 °C (to 2 °C in some locations inland). In present study the limit is 0 °C. |
| Dc | Tcold < 0 °C (to 2 °C). In present study the limit is 0 °C. | ||
| E | 1-3 months with T > 10 °C | - | |
| F | Twarm < 10 °C | Ft | Twarm > 0 °C |
| Fi | Twarm < 0 °C |