Cold: Difference between revisions
→Cooling: Laser cooling are techniques used to reach very low temperatures. |
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Another common method of cooling is exposing an object to [[ice]], [[dry ice]], or [[liquid nitrogen]]. This works by [[convection]]; the [[heat]] is transferred from the relatively warm object to the relatively cold [[coolant]]. |
Another common method of cooling is exposing an object to [[ice]], [[dry ice]], or [[liquid nitrogen]]. This works by [[convection]]; the [[heat]] is transferred from the relatively warm object to the relatively cold [[coolant]]. |
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[[Laser cooling]] are techniques used to reach very low temperatures. |
[[Laser cooling]] and [[Magnetic evaporative cooling]] are techniques used to reach very low temperatures. |
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==Notable cold locations and objects== |
==Notable cold locations and objects== |
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Revision as of 19:17, 24 December 2010
Cold (having less heat) refers to the condition or subjective perception of having low temperature.
The coldest theoretically possible temperature is absolute zero, which is 0 K on the Kelvin scale, a thermodynamic temperature scale, and −273.15 °C on the Celsius scale. Absolute zero is also 0 °R on the Rankine scale, another thermodynamic temperature scale, and −459.67 degrees on the Fahrenheit scale.
Cooling
Cooling refers to the process of becoming cold, or lowering in temperature. This could be accomplished by removing heat from a system, or exposing the system to an environment with a lower temperature.
Fluids used to cool objects are commonly called coolants.
Air cooling is the process of cooling an object by exposing it to air. This will only work if the air is at a lower temperature than the object, and the process can be enhanced by increasing the surface area or decreasing the mass of the object.
Another common method of cooling is exposing an object to ice, dry ice, or liquid nitrogen. This works by convection; the heat is transferred from the relatively warm object to the relatively cold coolant.
Laser cooling and Magnetic evaporative cooling are techniques used to reach very low temperatures.
Notable cold locations and objects
- The Boomerang Nebula is the coldest known natural location in the universe, with a temperature that is estimated at 1 K (kelvin) (−272.15 °C/−457.87 °F).[1]
- Herschel Space Observatory instruments and detectors are kept at temperatures below 2 K, using large helium tank for cooling.[2]
- The Universe is bathed in electromagnetic radiation that corresponds to a thermal equilibrium blackbody spectrum of roughly 2.725 kelvin.[3]
- Neptune's moon Triton has a surface temperature of −235 °C (−390 °F).
- Uranus with an atmospheric temperature of −215 °C (−355 °F).[4]
- Saturn with a temperature of −175 °C (−285 °F) at cloud tops.[5]
- Mercury, despite being close to the Sun, is actually cold during its night, with a temperature of about −170 °C (−275 °F). Mercury is cold during its night because it has no atmosphere to trap in heat from the Sun.[6]
- Jupiter with a temperature of −145 °C (−230 °F) at the cloud tops.[7]
- Mars has a temperature of about −125 °C (−195 °F).[8]
- The coldest continent on Earth is Antarctica.[9] The coldest place on Earth is the Antarctic Plateau,[10] an area of Antarctica around the South Pole that has an altitude of around 3000 metres. The lowest reliably measured temperature on Earth of −89.2 °C (−128.6 °F) was recorded there at Vostok Station on 21 July 1983[11] (See List of weather records).
- The first "pure" Bose–Einstein condensate was created by Eric Cornell, Carl Wieman, and co-workers at JILA on June 5, 1995. They did this by cooling a dilute vapor consisting of approximately two thousand rubidium-87 atoms to below 170 nK (one nK or nano K is a billionith (10^-9) of a degree Kelvin) using a combination of laser cooling (a technique that won its inventors Steven Chu, Claude Cohen-Tannoudji, and William D. Phillips the 1997 Nobel Prize in Physics) and magnetic evaporative cooling.
See also
References
- ^ "Boomerang Nebula boasts the coolest spot in the Universe". NASA's Jet Propulsion Laboratory. June 20, 1997. Retrieved July 8, 2009.
- ^ Jonathan Amos (9 February 2009). "'Silver Sensation' Seeks Cold Cosmos". BBC News. Retrieved 2009-03-06.
- ^ Hinshaw, Gary (December 15, 2005). "Tests of the Big Bang: The CMB". NASA WMAP. Retrieved 2007-01-09.
- ^ http://www.nasa.gov/worldbook/uranus_worldbook.html
- ^ http://www.nasa.gov/worldbook/saturn_worldbook.html
- ^ http://www.nasa.gov/worldbook/mercury_worldbook.html
- ^ http://www.nasa.gov/worldbook/jupiter_worldbook.html
- ^ http://www.nasa.gov/worldbook/mars_worldbook.html
- ^ http://earthobservatory.nasa.gov/IOTD/view.php?id=8070
- ^ Bignell, Paul (2007-01-21). "Polar explorers reach coldest place on Earth". The Independent. London. Retrieved 2010-04-30.
- ^ Budretsky, A.B. (1984). "New absolute minimum of air temperature". Bulletin of the Soviet Antarctic Expedition (in Russian) (105). Leningrad: Gidrometeoizdat.