Wiktionary
lightning mapper
n. 1 (context meteorology English) A system that displays a map of the position of recorded or real-time lightning discharges relative to the user or other objects. 2 (context instrumentation English) The component of such a system that gathers the required data, comprised of an interconnected network of electric field change sensors that measure the time of arrival of electric field pulses from the strokes in a lightning flash. 2D maps require 3 such sensors, 3D maps require 4.