Multiple choice general knowledge science & technology Hygrology Study of fishes Study of Sleep Study of Health and Hygiene Study of Humidity Reveal answer Fill a bubble to check yourself D Correct answer Explanation Hygrology is the study of humidity and moisture in the atmosphere. The prefix 'hygro-' relates to moisture or water (as in hygrometer). This is distinct from ichthyology (fish), hypnology (sleep), or general health studies.