The Lightning Flash 229
Flash
number of flashes for
low structure heights
and overestimate the number of flashes for high structure heights. Or,
more probably, it may be that Eriksson's curve is for a combination of flat and mountainous terrain.
However, since upward strokes occur for high structures,
for heights aboveabout 100 meters this equation is not totally valid for the important negative downward stroke.
Eriksson then presented an equation for the number of upward strokes
in per unit of the total number of strokes N(G):