IPA: /ˌaɪsoʊˈhaɪətəl/
KK: /aɪsoʊˈhaɪətəl/
Related to lines on a map that connect points of equal rainfall or precipitation.
The isohyetal map showed the distribution of rainfall across the region.
Isohyetal is formed from "iso-" (meaning equal) and "hyetis" (from Greek, meaning rain). The term refers to lines on a map connecting points of equal rainfall, thus indicating areas of equal precipitation.
Think of 'equal' ('iso-') rainfall ('hyetis') to remember that 'isohyetal' refers to areas with the same amount of rain.