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Temperature - Temperature Extremes

temperatures liquid zero absolute

The highest recorded weather temperature on Earth was 136°F (57.8°C), observed in North Africa in 1922. The record low temperature is -129°F (-89.2°C), observed in the Antarctic in 1983. Elsewhere in the universe, temperature extremes are much greater. The average surface temperatures of the most distant planets in our solar system (Uranus, Neptune, Pluto) are about 53K (-364°F; - 220°C;). Although temperatures on and within the sun vary, the core is about 27 million° F (15 million° C). (At very high temperatures Celsius and Kelvin temperatures are virtually identical; the 273 is negligible).

Temperatures produced in laboratories can be even more extreme. The study of very low temperatures, called cryogenics, is an active field of scientific research because of the unusual properties of many substances when they are close to absolute zero. Using magnetic techniques, temperatures below one microkelvin have been achieved. (A microkelvin, μ K, is 0.000001K.) Absolute zero itself, however, has not yet been reached.

Less extreme low temperatures can be obtained relatively easily with dry ice or liquid nitrogen. Dry ice, solid carbon dioxide, vaporizes (sublimes) under normal pressures rather than melting to a liquid. The sublimation temperature of dry ice is 195K (-198°F; 78°C). Liquid nitrogen can be used to obtain even lower temperatures. It is used at its normal boiling point, which is of liquid nitrogen is 77K (-321°F; -196°C).

Scientific interest in very high temperatures is largely due to the hope of achieving controlled nuclear fusion—the energy producing process in the sun and stars. By the use of powerful lasers, temperatures over 400 million kelvins have been achieved for short periods of time.

Resources

Books

Atkins, Peter W. The Second Law. New York: Freeman, 1984. Klein, Herbert A. The Science of Measurement. New York: Dover, 1974.

Periodicals

Kikoyin, A. "Temperature, Heat, and Thermometers." Quantum (May 1990): 16-21.

"Temperature And Rainfall Tables: July 2002." Journal of Meteorology 27, no. 273 (2002): 362.

"Weather Extremes: July 2002." Journal Of Meteorology 27 no. 273 (2002): 361.


John C. Whitmer

KEY TERMS

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Absolute temperature scale

—A temperature scale that has the lowest possible temperature set at absolute zero.

Absolute zero

—Absolute zero is the lowest temperature possible. It is associated with the absence of molecular motion and is equal to 0K (-459°F [- 273°C]).

Kinetic energy

—Energy of an object or system due to its motion.

Molecular translational energy

—Kinetic energy of an object or system due to the random constantly changing motion of individual molecules (or atoms) relative to each other.

Thermal equilibrium

—A condition between two or more objects in direct thermal contact in which no energy as heat flows from one to the other. The temperatures of such objects are identical.

Thermometer

—A device for obtaining temperature by measuring a temperature dependent property (such as the height of a liquid in a sealed tube) and relating this to temperature.

Triple point

—The unique temperature at which three phases of a single substance can coexist in equilibrium. The triple point for ice liquid water vapor is about 0.01°C above the normal freezing point of water.

[back] Temperature - The Kelvin Scale

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