An extended period of abnormally low precipitation that creates a serious water shortage relative to a region's normal climate and demand, affecting agriculture, water supply and ecosystems. Drought differs from simple aridity in being a temporary departure from expected conditions, and its severity is measured by indices tracking rainfall deficit, soil moisture and streamflow over time. Prolonged droughts, such as the 1930s Dust Bowl in the American Great Plains, have reshaped entire regional economies and populations.
Facts
PeriodicityCan last for days, months or years, and is a recurring feature of the climate in most parts of the world; annual dry seasons in the tropics significantly increase the chances of a drought developing. 1 ScaleMeasured with indices such as the Palmer Drought Severity Index, a regional index using precipitation and temperature data to monitor drought events and the areal extent and severity of drought episodes; droughts are also categorized as meteorological, agricultural or socioeconomic depending on cause. 1 First DescribedAmong the earliest documented climatic events, appearing in the Epic of Gilgamesh and tied to the Biblical story of Joseph's arrival in, and the later Exodus from, ancient Egypt. 1 Identification
Distinguishing AppearanceHas no single visible form but is marked cumulatively by drying wetlands, more and larger wildfires, and loss of biodiversity as vegetation and habitat dry out. 1 Connections
Associated With
Extended drought strips soil of moisture and vegetation cover, a major contributing cause of large dust storms, most famously during the 1930s Dust Bowl.
El Nino-Southern Oscillation phases are a well-documented driver of drought in specific teleconnected regions, such as El Nino-linked drought in Southeast Asia and Australia and La Nina-linked drought in the southwestern United States.
Heat waves and drought commonly reinforce one another: sustained high temperatures increase evaporation and deplete soil moisture, intensifying and prolonging drought conditions already underway.
Desert locust plagues are documented to follow the end of extended drought, when the heavy rains that break a drought create the moist soil conditions locusts need for mass breeding and swarm formation.
A desert superbloom typically follows the end of an extended drought, when unusually heavy rains after dry years trigger mass germination of a dormant wildflower seed bank.
Prolonged drought dries vegetation and soil moisture, a primary and well-documented driver of increased wildfire risk, frequency and severity.
Demonstrated By
Source National Oceanic and Atmospheric Administration
Source National Oceanic and Atmospheric Administration
Source National Oceanic and Atmospheric Administration
The climate of the Mediterranean Basin is defined by long, reliably dry summers, a seasonal drought pattern distinct from the wet winters of the region.
Source Encyclopaedia Britannica
Source National Oceanic and Atmospheric Administration
Source National Oceanic and Atmospheric Administration
Source National Oceanic and Atmospheric Administration
Source National Oceanic and Atmospheric Administration
The Taklamakan sits in the deep rain shadow of surrounding mountain ranges, making it one of the driest and most drought defined deserts on Earth.
Source Encyclopaedia Britannica
Sources
1. Drought (Wikipedia)
WikipediaWikipedia 'Drought', lead section
A drought can last for days, months or years.
Wikipedia 'Drought', Types section
Palmer drought index (sometimes called the Palmer drought severity index (PDSI)): a regional drought index commonly used for monitoring drought events and studying areal extent and severity of drought episodes.
Wikipedia 'Drought', History section
Drought is among the earliest documented climatic events, present in the Epic of Gilgamesh and tied to the Biblical story of Joseph's arrival in and the later Exodus from ancient Egypt.
Wikipedia 'Drought', Effects section
Environmental effects include the drying of wetlands, more and larger wildfires, loss of biodiversity.
View the Source National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric Administration- Demonstrated By: Savanna
- Demonstrated By: Kalahari Desert
- Demonstrated By: Patagonian Steppe
- Demonstrated By: Atacama Desert
- Demonstrated By: Pampas
- Demonstrated By: Sahel
- Demonstrated By: Karakum Desert
View the Source Encyclopaedia Britannica
Encyclopaedia Britannica, Inc.- Demonstrated By: Mediterranean Basin
- Demonstrated By: Taklamakan Desert
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