What do isobars represent on a weather map?

Concept overview / definition Key idea: Weather and climate maps use isolines to show equal values of a variable across space. For pressure, the isolines are called isobars, and they help visualize pressure distribution clearly.

Why the correct option is correct An isobar literally represents “equal pressure”. So it is defined as a line joining locations with the same atmospheric pressure (typically reduced to sea level for standardization). This allows quick interpretation of pressure patterns and supports wind and weather inference in later topics.

Why the other options are incorrect Lines of equal temperature are isotherms, not isobars. Lines of equal rainfall are isohyets. Lines of equal height/relief are contour lines. Mixing these terms is a common source of wrong answers in prelims maps-based MCQs.

UPSC exam tip / common confusion Elimination trick: Look for the “iso-” word matching the variable (bar = pressure, therm = temperature, hyet = rainfall). If a question mentions pressure map lines, the correct term is isobars, not any other isoline.