Thermals Are Underwear and Also Rising Air
Thermal means relating to heat. As a noun it covers warm underclothes and the columns of rising air that gliders climb.
Thermal means relating to heat. The noun goes two ways: *thermals* are insulating undergarments, and a *thermal* is a column of rising warm air. Gliders and birds circle inside them to gain height without power, which is why buzzards spiral over ploughed fields on sunny days.
- Relating to heat. *Thermal insulation.*
- A rising column of warm air. *Circling in a thermal.*
- Thermals — warm underclothes. *A set of thermals.*
Word forms
| Form | Word | Example |
|---|---|---|
| Adjective | thermal | Thermal imaging. |
| Noun | thermal | A strong thermal. |
| Plural | thermals | Wearing thermals. |
| Related | thermometer | A digital thermometer. |
| Related | thermostat | Turn down the thermostat. |
How it is used in a sentence
- Thermal imaging shows heat loss.Building surveys.
- The glider found a thermal over the quarry.Rising air.
- Pack thermals; it will be freezing.Clothing.
The heat family
- Thermometer — measures temperature
- Thermostat — holds a temperature steady
- Thermos — a vacuum flask, originally a trade name
- Thermodynamics — the physics of heat and energy
- Hypothermia — dangerously low body temperature
From Greek *therme*, heat, from *thermos*, hot. The word entered English through nineteenth-century physics and spread outward.
How do gliders use thermals?
They circle inside a rising column of warm air, gaining height, then glide onward to the next one. Birds do the same thing.
Why is a vacuum flask called a Thermos?
It began as a trade name from the Greek for hot, and became a general word in several countries.