Fig. 4

Diel distributions of land (empty markers) and sea (full markers) normalized frequencies of high Ip cloud-to-ground strokes above different peak current thresholds (Ip > 30,50,100 and 200 kA, left Y axis) compared the normalized fair-weather atmospheric electric field Carnegie Curve (Blue dashed line, right Y axis), that was calculated according to Harrison25. The time axis in UT.