To find the wettest spot on Earth is fairly simple, and, no, I don’t mean just any blue portion on the map. How wet or dry a place is gets measured by annual precipitation, so the wettest place is where there’s the most rainfall, snow, etc.
But what is the driest place on Earth ?
It turns out, rather than cracked sand floors, it’s located at the very bottom of the map in Antarctica, in a place known as the Dry Valleys.
Dry Valleys, Antarctica
The driest place on Earth is located in a part of Antarctica known as the Dry Valleys. Also known as the McMurdo Dry Valleys for being near Antarctica’s McMurdo Sound, portions of the Dry Valleys, such as the Friis Hills rising above Taylor Valley, haven’t seen water flowing over it for up to 14 million years!
You may think of Antarctica as a place of blinding whiteness, but the Dry Valleys in Victoria Land are a polar desert which are mostly ice-free.
The Dry Valleys are made up of Taylor Valley, Wright Valley, and Victoria Valley as the main “dry valleys,” as well as several other valleys, glaciers, and even some lakes and rivers. One reason for the unique dryness here is due to the surrounding mountains, which block any chances of ice flowing in from the East Antarctic Ice Sheet.
Another reason for the extreme dryness is katabatic winds, powerful winds spurred on by gravity to pull higher-density air from mountains down into the valleys, reaching speeds of up to 200 mph (320 km/h)! With such high speed winds pummeling the Dry Valleys, the friction and heat wick any remaining moisture away and evaporate any stray water or ice.
In fact, scientists have been using the McMurdo Dry Valleys to get a sense of Martian terrain, as the Dry Valleys represent the Earth environment most similar to Mars.
The Atacama Desert
For those of you looking for a “real” desert as the driest place on Earth, let’s travel about 5,600 miles (9,012 km) to northern Chile in South America.
The Atacama Desert is located in the northern third of Chile near its border with Peru, from around the city of La Serena in Coquimbo north to around the city of Arica. Some organizations include the very southern part of Peru to be part of the Atacama Desert.
The Atacama Desert earns the distinction of being the driest non-polar place on Earth, an area of extreme aridity (lack of moisture). This is due to the double whammy of temperature inversion (where warmer air remains above cooler air) and a two-sided rain shadow (dry area on one side of a mountain, here it’s on both sides).
While there is almost a complete lack of precipitation in the Atacama Desert, there are times when it gets rain. And, as deserts are known for, when it rains, it pours. In March of 2015, there was such heavy rainfall that it flooded some areas and resulted in 100+ deaths.