Section 3 of 4
A desert is a rainfall figure
Definitions that surprise people.
Desert pavement is a lag surface: wind has removed the fines and left the stones interlocked.
Photo: Desert pavement 2 · Wikimedia Commons
4 guides in this section
- A desert is a rainfall figure
Aridity is defined by precipitation against evaporation, which is why the largest desert on the planet is Antarctica and why sand is beside the point.
- The largest land biome, and almost nobody in it
The boreal forest wraps the northern hemisphere and holds a very small human population and a very large amount of carbon.
- Permafrost is a soil temperature, not a place
The definition is two years below zero, which means the map of it is drawn from boreholes rather than from the surface.
- Temperate grassland, and why it is not savannah
Same growth form, different rainfall regime, different fire return — and almost all of it now ploughed.