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#31
THERM/THERMO comes from the Greek word meaning "warm." A thermometer measures the amount of warmth in a body, the air, or an oven; a thermostat makes sure the temperature stays at the same level. In a thermodynamic process, heat affects the behavior of atoms, particles, or molecules. Thermoelectricity is produced by the direct action of heat on certain combinations of metals.
thermal (1) Of, relating to, or caused by heat. (2) Designed to insulate in order to retain body heat.
eg. The glider circled slowly, seeking a thermal updraft from a plowed field that would take it spiraling upward.
Before polypropylene and thermal weave, union suits - that is, long thermal underwear that covered the entire body - were sometimes donned in October and not taken off until April. Worn by sodbusters, cowboys, and townsfolk alike, they kept America warm during its formative years. They undoubtedly also kept America itchy and a little on the smelly side through the cold months. But then, bathing even once a week was considered the height of cleanliness until very recently.
thermoclinel The region in a body of water that divides the warmer, oxygen-rich surface layer from the colder, oxygen-poor deep water.
eg. The warm water above the termocline is relatively shallow: for most of the world's oceans the top layer is only about 150 to 300 feet deep.
The -cline of thermocline comes from a Greek word meaning "to slope" and refers to the gradual series of temperature changes that occur in this kind of zone. In a freshwater lake there is very little mixing between the layers of warm and cold water during the summer. During the autumn, however, a major turnover occurs. The oxygen-rich surface water cools and sinks to the bottom, and the nutrient-rich water near the bottom is displaced to the top. The cycle is reversed the following spring.
thermocouple A device for measuring temperature that makes use of the way different metals respond to heat.
eg. Thermocouples can be used to measure temperatures as high as 2300 C or as low as -270 C, far beyond the range of ordinary thermometers.
Thermocouples use wires made of two different metals, such as copper and iron. The wires are joined at both ends; one end is placed against the object whose temperature is being measured, while the other end is kept at a known, constant temperature. The thermocouple generates a voltage that depends on the difference in temperature between the two joined ends of the wires and can be measured to obtain the temperature of the object.
thermonuclear Of or relating to the changes in the nucleus of atoms with low atomic weight, such as hydrogen, that require a very high temperature to begin.
eg. During the 1950s and 1960s american families built thousands of home underground shelters to protect themselves from thermonuclear blasts.
The sun's light comes from a sustained thermonuclear reaction deep sithin it. On earth, such thermonuclear reactions have been used to develop the hydrogen bomb, a bomb based on a fusion reaction that must be triggered by a fission bomb that uses uranium or plutonium. "Litter Boy" and "Fatman", the bombs dropped on Hiroshima and Nagasaki ti end World War II, were fission bombs. The thermonuclear era began only in 1952, and has produced bombs hundreds of times more powerful.
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