isokeraunic 1. Having thunderstorm phenomena of equal frequency or severity, or simultaneous occurrence. 2. A line on a map that connects places of equal thunderstorm frequency.
Found on http://www.wordinfo.info/words/index/info/view_unit/2795/5
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.
Found on http://www.wordinfo.info/words/index/info/view_unit/2795/2
line connecting points of equal occurrence of thunderstorms
Found on http://phrontistery.info/i.html
No exact match found