Things people say
Desert myths
“Deserts are all sand”
Sand covers only about 20 percent of the Earth's deserts. USGS Most of the sand is in sand sheets and sand seas: vast regions of undulating dunes. USGS Nearly 50 percent of desert surfaces are plains where wind has exposed loose gravels. USGS
“Deserts are always hot”
Though normally associated with hot, sandy environments, cold deserts are also widespread. Met Office The Gobi Desert of east Asia is one example, where annual average temperatures can be below 0 degrees C. Met Office Whether hot or cold, deserts pose great challenges for the plants and animals that live there, which must adapt to extreme, prolonged water deficits. Met Office Polar deserts are given a mean annual precipitation less than 250 millimeters and a mean temperature during the warmest month of less than 10 degrees C. USGS Antarctica is a desert. British Antarctic Survey
Are polar deserts "deserts"?
USGS includes polar deserts, giving them a mean annual precipitation less than 250 millimeters and a mean temperature during the warmest month of less than 10 degrees C, and says they cover nearly 5 million square kilometers. Britannica notes that some definitions include "frigid deserts," but the account we checked restricts the term to hot and temperate deserts. We report both approaches.
“The Sahara is simply the largest desert, full stop”
The Sahara of Africa is the world's largest desert, in USGS wording. USGS Antarctica is a desert. British Antarctic Survey
Which desert is the largest?
USGS calls the Sahara of Africa "the world's largest desert" in its types essay (a non-polar framing in that sentence). The British Antarctic Survey says "Antarctica is a desert," with snowfall equivalent to only 150mm of annual rain. We report both wordings. We do not call Antarctica the world's largest desert, because none of the sources we checked for this site use that phrase.
“It never rains in the Atacama”
In the Atacama, measurable rainfall of 1 millimeter or more may occur as infrequently as once every 5-20 years. USGS Some areas of the Atacama are touched by rain only four times a century. NASA Other areas have never received rainfall for as long as records have been kept. NASA
How often does it rain in the Atacama?
USGS says that in the Atacama, measurable rainfall of 1 millimeter or more may occur as infrequently as once every 5-20 years. NASA Earth Observatory says some areas of the Atacama are touched by rain only four times a century, and other areas have never received rainfall for as long as records have been kept. Those are different statements about different places and timescales, so we keep both.
“The real danger is thirst”
More people drown in deserts than die of thirst. USGS Normally dry stream channels, called arroyos or wadis, can quickly fill after heavy rains, and flash floods make these channels dangerous. USGS