The lowest natural temperature ever directly recorded at ground level on Earth is -89.2 °C (-128.6 °F; 184.0 K) at the Soviet Vostok Station in Antarctica on July 21, 1983 by ground measurements.
A 2009 study estimated that under exceptional climate conditions similar to those recorded at Vostok in 1983, temperatures on the plateau around Dome Argus could drop lower than -95 °C (-139 °F; 178 K). On August 10, 2010, satellite observations measured a surface temperature of -93.2 °C (-135.8 °F; 180.0 K) at 81.8°S 59.3°E / -81.8; 59.3, along a ridge between Dome Argus and Dome Fuji, at 3,900 m elevation. The result was reported at the 46th annual meeting of the American Geophysical Union in San Francisco, in December 2013; it is a provisional figure, and may be subject to revision. The value may not be listed as the record lowest temperature as it was measured by remote sensing satellites and not by ground-based thermometers, unlike the 1983 record. The temperature announced reflects that of the ice surface, while the Vostok readings measured the air above the ice, and so the two are not directly comparable.
Video Lowest temperature recorded on Earth
Historical progression
On January 21, 1838 a recording was made by the Russian merchant Neverov in Yakutsk, of -60 °C (-76 °F; 213 K). On January 15, 1885 H. Wild reported that a temperature of -68 °C (-90 °F; 205 K) was noted in Verkhoyansk. A later measurement at the same place in February 1892 was reported as -69.8 °C (-93.6 °F; 203.3 K). Soviet researchers later announced a recording of -67.7 °C (-89.9 °F; 205.5 K). According to a 2012 documentary filmed by 60 Minutes Australia entitled Chilling Out, visiting the coldest place on Earth, in the 1920s in Oymyakon, a temperature of -71.2 was recorded and thus the town square is built around the monument built to commemorate this event. In February 1933 at Oymyakon, about 650 km (400 mi) to the south-east of Verkhoyansk; this measurement was reported by Soviet texts through the 1940s as a record low, with the previous measurement from Verkhoyansk retroactively adjusted to -67.6 °C (-89.7 °F; 205.6 K).
The next reliable measurement was made during the 1957 season at the Amundsen-Scott South Pole Station in Antarctica, yielding -73.6 °C (-100.5 °F; 199.6 K) on May 11 and -74.5 °C (-102.1 °F; 198.7 K) on September 17. A subsequent measurement of -88.3 °C (-126.9 °F; 184.8 K), on August 24, 1960, held the record until a temperature of -89.2 °C (-128.6 °F; 184.0 K) was measured at the Soviet Vostok Station, on the Antarctic Plateau, on July 21, 1983. This remains the record for a directly recorded temperature.
Maps Lowest temperature recorded on Earth
Laboratory cooling
Early experiments
In 1904 Dutch scientist Heike Kamerlingh Onnes created a special lab in Leiden with the aim of producing liquid helium. In 1908 he managed to lower the temperature to less than -269 °C (-452.2 F, 4 K), which is less than four degrees above absolute zero. Only in this exceptionally cold state will helium liquefy, the boiling point of helium being at -268.94 °C (-452.092 F). Kamerlingh Onnes received a Nobel Prize for his achievement.
Onnes' method relied upon depressurising the subject gases, causing them to cool by adiabatic cooling. This follows from the first law of thermodynamics;
where U = internal energy, Q = heat added to the system, W = work done by the system.
Consider a gas in a box of set volume. If the pressure in the box is higher than atmospheric pressure, then upon opening the box our gas will do work on the surrounding atmosphere to expand. As this expansion is adiabatic and the gas has done work
Now as the internal energy has decreased, so has the temperature.
Modern experiments
As of November 2000, nuclear spin temperatures below 100 pK were reported for an experiment at the Helsinki University of Technology Low Temperature Lab. However, this was the temperature of one particular type of motion--a quantum property called nuclear spin--not the overall average thermodynamic temperature for all possible degrees of freedom. At such low temperatures, the concept of "temperature" becomes multifaceted since molecular motion cannot be assumed to average out across degrees of freedom. The corresponding peak emission will be in radio waves, rather than in the familiar infrared, so it is very inefficiently absorbed by neighboring atoms, making it difficult to reach thermal equilibrium.
Low Temperature Laboratory recorded a record low temperature of 100 pK, or 1.0 × 10-10 K in 1999.
The current apparatus for achieving low temperatures has two stages. The first utilizes a helium dilution refrigerator to get to temperatures of millikelvins, then the next stage uses adiabatic nuclear demagnetisation to reach picokelvins.
Extremely low temperatures are useful for observation of quantum mechanical phases of matter such as superfluids and Bose-Einstein condensates, which would be disrupted by thermal motion.
See also
- Absolute zero
- Dilution refrigerator
- Highest temperature recorded on Earth
- List of weather records
- Magnetic refrigeration
- Orders of magnitude (temperature)
- Timeline of low-temperature technology
References
External links
- Details of HUT experiment, including details of the cryostat
Source of article : Wikipedia
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