thermal
American Heritage Dictionary:
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ther·mal
(thûr'məl) 
adj.
A rising current of warm air.
thermally ther'mal·ly adv.
adj.
- Of, relating to, using, producing, or caused by heat.
- Intended or designed in such a way as to help retain body heat: thermal underwear.
A rising current of warm air.
thermally ther'mal·ly adv.
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thermal
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thermal
IN BRIEF: Of or pertaining to heat, caused by or saving heat. Also: A warm upward-moving current of air.
Do you wear thermal underwear on cold winter days?
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A column of rising air heated by the sun or other phenomena. Sailplane and glider pilots use it for soaring. The pilots recognize the presence of a thermal with the help of a variometer—an instrument having two tubes with red and green indicators. A red means a downward air current, and a green means an upward air current, or a thermal. See variometer.
Saunders Veterinary Dictionary:
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thermal
Pertaining to heat.
- t. death point — the state of heat content, as measured by temperature, at which the life of an organism ceases. Important in a consideration of sterilization procedures for certain organisms, especially those that produce spores.
- t. energy — the energy of heat.
- t. injury — see burn.
- t. processing — the preservation of food by the application of heat either in boiling water, by live steam, in an autoclave or by flame.
- t. sensation — the sense of temperature.
- t. stress — see hyperthermia (1), heat stroke, fever.
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categories related to 'thermal'
- Forecasting and Meteorology - thermal: rising current of warm air
Wikipedia on Answers.com:
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Thermal
This article is about the atmospheric phenomenon. For other uses of the term thermal, see thermal (disambiguation).
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This article relies largely or entirely upon a single source. Please help improve this article by introducing citations to additional sources. Discussion about the problems with the sole source used may be found on the talk page. (July 2009) |
A thermal column (or thermal) is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. The Sun warms the ground, which in turn warms the air directly above it.[1] Dark earth, urban areas and roadways are good sources of thermals.
The warmer air expands, becoming less dense than the surrounding air mass. The mass of lighter air rises, and as it does, it cools due to its expansion at lower high-altitude pressures. It stops rising when it has cooled to the same temperature as the surrounding air. Associated with a thermal is a downward flow surrounding the thermal column. The downward moving exterior is caused by colder air being displaced at the top of the thermal.
The size and strength of thermals are influenced by the properties of the lower atmosphere (the troposphere). Generally, when the air is cold, bubbles of warm air are formed by the ground heating the air above it and can rise like a hot air balloon. The air is then said to be unstable. If there is a warm layer of air higher up, an inversion can prevent thermals from rising high and the air is said to be stable.
Thermals are often indicated by the presence of visible cumulus clouds at the apex of the thermal. When a steady wind is present thermals and their respective cumulus clouds can align in rows oriented with wind direction, sometimes referred to as "cloud streets" by soaring and glider pilots. Cumulus clouds are formed by the rising air in a thermal as it ascends and cools, until the water vapor in the air begins to condense into visible droplets. The condensing water releases latent heat energy allowing the air to rise higher. Very unstable air can reach the level of free convection (LFC) and thus rise to great heights condensing large quantities of water and so forming showers or even thunderstorms.
Thermals are one of the many sources of lift used by soaring birds and gliders to soar.
Thermals on the sun typically form hexagonal prisms (Bénard cells).
References
- ^ Bradbury, Tom (2000). Meteorology and Flight: Pilot's Guide to Weather (Flying & Gliding). A & C Black. ISBN 0-7136-4226-2.
See also
External links
- What do thermals look like? - Thermal Structure and Behavior by Wayne M. Angevine
- Time-lapse video of clouds caused by thermals forming and decaying
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Translations:
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Thermal
Dansk (Danish)
adj. - varme-, termisk, varm
n. - termisk opvind, termik
idioms:
- thermal printer termisk printer
- thermal wax printer termisk voksprinter
Nederlands (Dutch)
warmte-, warmwater-, thermisch, opstijgende warme luchtstroom
Français (French)
adj. - thermal, thermique
n. - ascendance thermique, courant ascendant
idioms:
- thermal printer imprimante thermique
- thermal wax printer imprimante à cire thermique
Deutsch (German)
n. - Thermik, (aufwärts gerichtete Warmluftbewegung), kälteisolierende Kleidung
adj. - thermisch, Wärme-, heiß
idioms:
- thermal printer Thermodrucker
- thermal wax printer Thermo-Wax-Drucker
Ελληνική (Greek)
n. - ρεύμα θερμού αέρα
adj. - (φυσ.) θερμικός, θερμαντικός
idioms:
- thermal printer (Η/Υ) θερμικός εκτυπωτής
- thermal wax printer θερμικός εκτυπωτής κηρού
Italiano (Italian)
corrente ascendente, termale
Português (Portuguese)
n. - termal
adj. - térmico (m), calorífico (m)
Русский (Russian)
теплый, горячий, термальный, тепловой, теплотворный
Español (Spanish)
adj. - térmica, térmico, termal
n. - corriente térmica
idioms:
- thermal printer impresora térmica
- thermal wax printer impresora que utiliza una cinta cubierta con cera
Svenska (Swedish)
n. - termisk uppvind
adj. - värme-, termisk-
中文（简体）(Chinese (Simplified))
热的, 烫的, 热量的, 上升温暖气流
idioms:
- thermal printer 热感式接口
- thermal wax printer 热蜡式接口
中文（繁體）(Chinese (Traditional))
adj. - 熱的, 燙的, 熱量的
n. - 上升溫暖氣流
idioms:
- thermal printer 熱感式介面
- thermal wax printer 熱蠟式介面
한국어 (Korean)
adj. - 열의, 보온성이 좋은, 정열적인
n. - 상승 온난 기류
日本語 (Japanese)
adj. - 熱の, 温泉の, 熱い
n. - サーマル
idioms:
- thermal power station 火力発電所
العربيه (Arabic)
(الاسم) ألحار (صفه) حار, حراري
עברית (Hebrew)
adj. - של חום, חומני, תרמי
n. - זרם אוויר חם, ברבים: לבנים תחתונים מחממים
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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
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This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Thermal.
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