Meaning & use
isotherm
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Meanings
nouncountable
A line on a weather map or chart that joins places having the same temperature.
Grammar: Countable; the plural is isotherms. An isobar, by contrast, joins points of equal pressure.
Patterns
- an isotherm on a map
- isotherms show something
- draw an isotherm
On the January climate map, the 0°C isotherm runs just south of the Great Lakes.
Weather forecasters use isotherms to show how cold air is spreading across the country.
nouncountablephysicschemistry
In physics and chemistry, a curve showing how two quantities, usually pressure and volume, relate at a constant temperature.
Grammar: Countable; mostly used in scientific writing, often in compounds like adsorption isotherm.
Patterns
- an adsorption isotherm
- plot an isotherm
- fit an isotherm to data
The adsorption isotherm describes how much gas a solid surface can hold at a fixed temperature.
Students plotted an isotherm to study how the gas volume changed as pressure increased.
Word forms
| plural | isotherms |
|---|
Common combinations
- temperature isotherm
- The 20°C temperature isotherm marks the northern limit of the citrus-growing region.
- adsorption isotherm
- The lab measured an adsorption isotherm for water vapor on activated carbon.
- map of isotherms
- A map of isotherms makes it easy to compare climates at a glance.
- isotherm analysis
- Her thesis included an isotherm analysis of heat flow through the wall.
Synonyms and how they differ
- contour line
- A contour line joins points of equal value for any variable, such as height or pressure; an isotherm is specifically for temperature.
Word family
- isothermal adjective
- Happening or existing at a constant temperature; also describes lines of equal temperature.
- isothermally adverb
- In a way that keeps the temperature constant.
Commonly confused: isotherm or isobar?
isotherm vs isobar
An isobar joins points of equal atmospheric pressure, while an isotherm joins points of equal temperature; both appear on weather maps.
Practice
On a weather map, an isotherm connects places with the same ______.
Choose one answer.
An isotherm always joins points of equal temperature. 'Pressure' is tempting because it is also shown on weather maps, but a line of equal pressure is called an isobar.
Make it your own
Write a sentence using “isotherm”, then check it and compare it with the examples above.