Hello student ,

In common meteorological usage, a line of equal or constant value of a given quantity, with respect to either space or time;
same as isogram .

Isometric line is a line (such as a contour line) drawn on a map and indicating a true constant value throughout its extent.

In the "isopleth" map, the values are rates or ratios computed for areal units, such as census tracts, town- ships, precincts, or counties whereas in the "isometric" map the values are samples of absolute measurement taken at different points on a map.