Potential evapotranspiration in the context of "Climate model"

The tundra climate is a polar climate sub-type located in high latitudes and high mountains. It is classified as ET according to the Köppen climate classification. It is a climate which at least one month has an average temperature high enough to melt snow (0 °C [32 °F]), but no month with an average temperature in excess of 10 °C (50 °F). If the climate occurs at high elevations, it is known as alpine climate.

Despite the potential diversity of climates in the ET category involving precipitation, extreme temperatures, and relative wet and dry seasons, this category is rarely subdivided. Rainfall and snowfall are generally slight due to the low vapor pressure of water in the chilly atmosphere, but as a rule potential evapotranspiration is extremely low, allowing soggy terrain of swamps and bogs even in places that get precipitation typical of deserts of lower and middle latitudes. The amount of native tundra biomass depends more on the local temperature than the amount of precipitation.

Charles Warren Thornthwaite (March 7, 1899 – June 11, 1963) was an American geographer and climatologist. He is best known for devising the Thornthwaite climate classification, a climate classification system modified in 1948 that is still in use worldwide, and also for his detailed water budget computations of potential evapotranspiration.

He was Professor of Climatology at Johns Hopkins University, adjunct professor at Drexel University, President of the Commission for Climatology of the World Meteorological Organization, a recipient of the Outstanding Achievement Award of the Association of American Geographers, and the Cullum Geographical Medal from the American Geographical Society.