even if it works fine, beleive me this circuit is not professional at all.
as pholba and myself said, you need a resistance in series with the LED, and you have to check the datahseet and see the 2 threshholds.. but again, you do not have any control over the amplification. NO it does not act as an amplifier, it acts as a diffrentiator, whose referece is fixed.
do what you want, this design may be simple but its not reliable. tell me, what are you gonna do if the lightning conditions changed to an extent that cannot be adjusted with the POT ??