isoterme

Isoterme isoterme refer to lines or concepts associated with constant temperature. The term derives from the Greek iso- meaning equal and therme meaning heat, and it appears in both meteorology and thermodynamics, with related uses in cartography and the earth sciences.

In meteorology and climatology, isotherms (plural; isoterme in some languages) are lines on maps that connect points sharing the same temperature. They help visualize temperature gradients, seasonal patterns, and air-mass distributions. Isotherms are commonly used on weather maps alongside isobars (lines of equal pressure) to interpret atmospheric conditions, forecast fronts, and study climate regions. In oceanography, sea-surface isotherms illustrate temperature distribution in the oceans, informing studies of currents and climate change.

In thermodynamics, an isothermal process is one in which the absolute temperature of a system remains constant during the transformation. For an ideal gas, the relation PV = nRT applies at constant T, so with fixed amount of substance n and constant T, the product PV is constant. Real systems approximate isothermal behavior when heat exchange with the surroundings maintains a steady temperature.

Isotherms also appear in geology and soil science, where temperature distributions within the ground are mapped to study phenomena such as permafrost development and subsurface heat flow. They provide a simplified representation of thermal fields in both natural and engineered settings.

See also: Isotherm, Isobar, Thermodynamics, Weather map, Permafrost.