What is drought?
Drought is best described as a deficiency on precipitation compared to a climatological average. The more severe and prolonged the deficit, the worse the drought is. Droughts are also associated with warmer temperatures. Some droughts initiate with a combination of persistently warmer than average temperatures (from more anamolous upper-level ridging) and some start seeing more significant heat after a period of below average precipitation. A rapid onset or intensification of drought is called a flash drought.
Figure 1. Latest U.S. drought map from the U.S. Drought Monitor
As shown in Figure 2, there are five other types of drought: meteorological, agricultural, hydrological, ecological, and socio-economic.
Figure 2. Five types of drought
There is often overlap between the drought types. For example, it is possible for all five drought to co-exist during a particularly severe long-term drought. Often meteorological and agricultural drought are aligned earlier on and then hydrological, ecological, and socio-economic drought are aligned later on in a drought.
