noun. (meteorology) an isogram connecting points having the same temperature at a given time.
1. Noun, singular or mass The tropopause typically marks the uppermost limit of cloud activity; instead of rising above this isotherm, large storm clouds typically spread out horizontally in an anvil shape. 2. Adjective Step 4 follows another isotherm down and to the right to the point (1.8299 × 10-4, 101,325).