The coldest place on earth is colder than the thought of scientists

The tiny valleys near the top of the Antarctic ice cap are reaching temperatures near minus 100 degrees Celsius (minus 148 degrees Fahrenheit) in winter, according to a new study. The results could change scientists' understanding of how low temperatures can reach the Earth's surface, the researchers say.

Scientists announced in 2013 that they had found the lowest temperatures on the Earth's surface: sensors on several satellites observing the Earth have measured temperatures of minus 93 degrees Celsius (minus 135 degrees Fahrenheit) in several places of the Antarctic Plateau of the East. which includes the South Pole. But the researchers revised this initial study with new data and found that temperatures actually reached minus 98 degrees Celsius (minus 144 degrees Fahrenheit) during the southern polar night, mostly during July and August.

When the researchers announced for the first time that they had found the coldest temperatures on Earth five years ago, they determined that clear, persistent skies and light winds are needed for temperatures to go down. as low. But the new study adds a twist to the story: not only is clear skies needed, but the air must also be extremely dry, as water vapor traps heat in the air. ;air.

The researchers observed ultra-low temperatures in small troughs or troughs in the Antarctic ice sheet. The super-cold and super-dry air is denser than the slightly warmer air that surrounds it, so it falls in the troughs and becomes trapped. This allows the surface of the snow and the air above to cool down further, until the clear, calm and dry conditions change and the cold air mixes with it. Warmer air higher up in the atmosphere.

"In this area, we see incredibly dry air periods, allowing the surface's heat to radiate more easily into space," said Ted Scambos, Senior Researcher at the National Data Center. on snow and ice at the University of Colorado-Boulder and lead author of the new study Letters of geophysical research, a journal of the American Geophysical Union.

The record of minus 98 degrees Celsius is about as cold as possible on the surface of the Earth, according to the researchers. In order for the temperature to fall so low, clear skies and dry air must persist for several days. Temperatures could drop a bit more if conditions lasted several weeks, but this is extremely unlikely, Scambos said.

Find the coldest place

The high altitude of the Eastern Antarctic Plateau and its proximity to the South Pole give it the coldest climate of all regions of the planet. The lowest air temperature ever measured by a meteorological station, minus 89 degrees Celsius (minus 128 degrees Fahrenheit), was recorded at the Russian Vostok station in July 1983.

But weather stations can not measure temperatures everywhere. Thus, in 2013, Scambos and his colleagues decided to analyze data from several Earth observation satellites to see if they could find temperatures on the plateau even lower than those recorded at Vostok.

In the new study, they analyzed satellite data collected during the winter of the southern hemisphere between 2004 and 2016. They used data from the MODIS instrument aboard the Terra and Aqua satellites. NASA as well as NOAA polar operational environmental satellite data.

The researchers first saw a large plateau region at more than 3,500 meters (11,000 feet) above sea level where temperatures regularly dropped to less than 90 degrees Celsius (minus 130 degrees Fahrenheit) on the surface of the snow. The lowest temperature they observed was minus 93 degrees Celsius (minus 135 degrees Fahrenheit).

Data from MODIS instruments are calibrated using temperature measurements from ground weather stations. In 2016, NASA recalibrated MODIS data with more recent weather station measurements, and the researchers reanalyzed the temperature data. The weather conditions on the plateau have not changed, but the adjusted satellite data gave researchers a more accurate picture of the lowest temperature.

They found that the record low was about 5 degrees Celsius (9 degrees Fahrenheit) colder than what they originally reported, about minus 98 degrees Celsius (minus 144 degrees Fahrenheit). ).

How cold can he get?

Scambos and his colleagues analyzed the terrain where they saw these ultra-low temperatures and found that they were occurring in shallow cavities of 2 to 3 meters deep on the ice surface, on the south side of the highlands. peaks of the plateau. .

Interestingly, researchers have noticed a slew of places where temperatures plummeted almost exactly to this record level over the 14 year period, even though they were located hundreds of miles away. 39 one of the other. This led them to wonder: Is there a limit to the cold on the set?

In order for the temperature to drop to this low level, the sky must be clear and the air must be dried for several days. When the temperature drops below a certain point, the air cools so slowly that it can not become significantly colder before the weather changes, according to the researchers. Less than 98 degrees Celsius, then, seems to be the limit of how cold it can be on the surface of the Earth, Scambos said.

"There is a limit to the duration of the conditions that allow cooling at these ultra-low temperatures, and a limit to the amount of heat that you can actually cross, because the water vapor must be almost non-existent to emit from the heat of the surface at these temperatures, "he said.

The research team has developed a set of instruments designed to survive and operate at the coldest places throughout the winter in order to measure the temperature of snow and ice. ;air. They plan to deploy the instruments over the next two years.

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