thermo-, therm-, thermi-, -thermia, -therm, -thermal, -thermic, -thermias, -thermies, -thermous, -thermy
(Greek: heat, heating, heater, hot, warm)
The term heat is employed in ordinary language in different senses. Some scientists distinguish four principal applications of the term:
- Sensation of heat.
- Temperature, or degree of hotness.
- Quantity of thermal energy.
- Radiant heat, or energy of radiation.
An important criterion for thermal insulators or conductors.
2. The study of the independent and interactive biotic and abiotic components of naturally heated environments.
2. An expression of the effect of temperature on the rate of plant growth; assuming other condition are satisfactory.
3. The ratio of the amount of work performed by a heat engine in one cycle to the amount of thermal energy input required to operate the engine over one cycle; a measure of the efficiency of converting a fuel to energy and useful work.
2. The condition under which two substances in physical contact with each other exchange no heat energy.
British scientists have discovered that people experience far less pain when they touch a sore part of their body with their hand; so, a gentle rub may very well help pain go away, or at least decrease.
- The researchers investigated what is called the "thermal grill illusion" or TGI, where participants placed their index and ring fingers in warm water and the middle finger in cold water.
- With the TGI, or thermal grill illusion, the brain perceives the cool water as painfully hot.
- The study looked at heat perception after participants submerged their fingers in water of different temperatures and pressed their fingertips together in different combinations.
- This allowed scientists to study the experience of pain without actually causing any injury to those who participated in the studies.
- The scientists involved concluded that touching an apparently painful part of the body will affect the way pain signals travel to the brain.
- While touch may help an individual to cope with pain to some degree, perhaps by easing very mild pain from a minor injury, it is unlikely to completely eliminate the experience of pain.
- Pain is a very subjective experience, and many factors, including psychological and emotional factors, affect the way it is experienced.
During a thermal inversion, air pollution can increase dramatically as a mass of cold air is held in place below a warmer mass of air.
The absence of air circulation prevents the pollution near the earth's surface from escaping.
This can be a highly efficient method and has the experimental advantage of producing ions with a small energy spread characteristic of the filament temperature, typically a few tenths of an electron volt, as compared with beam energies of thousands of electron volts.
The filaments, generally made of platinum, rhenium, tungsten, or tantalum, are heated by current.
Surface ionization requires a nearby source of atoms, often another filament operating at lower temperatures.
Samples can also be loaded directly on the filament, a widely used and successful technique and one that has resulted in many interesting chemical treatments of the sample when it is deposited on the filament.
One such application changed lead from a difficult to an easy element to analyze, enabling important geochronological and environmental measurements.
A disadvantage of thermal ionization is the possible change in isotopic composition during the measurement. This effect is caused by Rayleigh distillation, wherein light isotopes evaporate faster than heavy ones.
Studies done on isotopes that come from radioactive decay; such as, those used in determining the ages of rocks, encounter this problem, but it is correctable using the measured values of the isotopes that are not radiogenic.
With few exceptions the use of a thermal source requires the chemical separation of the sample. Useful data are commonly obtained on extremely small (nanogram) samples.