thermal

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(thûr'məl) pronunciation
adj.
  1. Of, relating to, using, producing, or caused by heat.
  2. Intended or designed in such a way as to help retain body heat: thermal underwear.
n.
A rising current of warm air.

thermally ther'mal·ly adv.

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thermal

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pronunciation

IN BRIEF: Of or pertaining to heat, caused by or saving heat. Also: A warm upward-moving current of air.

pronunciation 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.

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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Random House Word Menu by Stephen Glazier
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Example of a thermal column between the ground and a cumulus

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

  1. ^ Bradbury, Tom (2000). Meteorology and Flight: Pilot's Guide to Weather (Flying & Gliding). A & C Black. ISBN 0-7136-4226-2. 

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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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