Concept: A line on a map that connects points with the same value of a weather element is called an isopleth, and its name depends on the element measured.Explanation:An isotherm joins places with equal temperature.An isohyet joins places with equal rainfall.An isobar joins places with equal atmospheric pressure.An isoneph joins places with equal cloudiness or cloud cover.Therefore, the correct term for equal cloudiness is isoneph.Answer: C. isoneph