1) Isoceraunic map 1) Isokeraunic 
isoceraunic, isokeraunic Indicating or having equal frequency or intensity of thunderstorm activity. An isoceraunic line is a line drawn through geographical points at which some phenomenon connected with thunderstorms has the same frequency or intensity; used for lines of equal frequency of lightning discharges.
representing, having, or indicating equality in the frequency or intensity of thunderstorms: isoceraunic line; isoceraunic map.