Where Is the Hottest Place on Earth? It Lies Somewhere Between Folklore and Science, the Desert and the City

In October 2004, ecologist Steve Running visited the Flaming Mountain, a ridge of dark red sandstone on the edge of the Taklimakan Desert and the Tian Shan range. The surface of the mountain is said to reach temperatures of 50 to 80°C (122 to 175°F) in the summer, and a nearby tourist center marks the spot with a huge golden thermometer. It is the hottest place in China, if not the world, or so says the local lore.

According to local lore, the Flaming Mountain is the hottest spot in China. After visiting the site, scientists used NASA data to find out for sure. (Photograph ©2011 oh contraire.)

And that got Running thinking: exactly where is the hottest place on Earth? With some colleagues at the University of Montana, he did some research and found that the location of the world’s hottest spot changes, though the conditions don’t. Think dry, rocky, and dark-colored lands.
In July 1913, observers in Furnace Creek, California—Death Valley—watched the thermometer reach 56.7°C (134°F) and declared it to be the highest temperature ever recorded on Earth. But just nine years later, on September 13, 1922, a weather station in El Azizia, Libya, recorded a temperature of 58.0°C (136.4°F). According to the World Meteorological Organization (WMO), that remains the highest air temperature ever measured.
“Yet most of the places that call themselves the hottest on Earth are not even serious contenders,” says Running. The reason is partly about where the measurements are made. But it is also a tale about how temperature is measured.

In the remote, sparsely populated areas that are likely to be the world’s hottest, weather stations (black dots) are widely spaced. Satellites provide a global view that can fill in the gaps. (Map by Robert Simmon, using data from the WMO & Natural Earth.)

“The World Meteorological Organization has approximately 11,119 weather stations on Earth’s land surface collecting surface temperature observations,” notes David Mildrexler, also from the University of Montana. “When compared to the 144.68 million square kilometers of land surface, that’s one station every 13,012 square kilometers.”
“The Earth’s hot deserts—such as the Sahara, the Gobi, the Sonoran, and the Lut—are climatically harsh and so remote that access for routine measurements and maintenance of a weather station is impractical,” he adds. “The majority of Earth’s hottest spots are simply not being directly measured by ground-based instruments.”
That’s where satellites come in.
For a dozen years, NASA has operated the Moderate Resolution Imaging Spectroradiometer (MODIS) on two different satellites; first on Terra (launched in 1999) and then on Aqua (2002). The instrument has 36 different spectral bands (groups of wavelengths) and many ways to view the planet. One of them is the detection of thermal radiance, or the amount of infrared energy emitted by the land surface. Since the two MODIS instruments scan the entire surface each day, they can provide a complete picture of earthly temperatures and fill in the gaps between the weather stations.

By Michael Carlowicz
Design by Robert Simmon
April 5, 2012.

- Earth Observatory - NASA