I really don't like commenting on others pics when i'm using the laptop as the screen is pretty poor. BUT that first shot is very, very good so I just had too. The second shot is also good and doesn't seem too dark here but as i've just explained.......
Never been lucky enough to shoot lightning before but something i'd like to try if you have any tips?
Do I have to assume that the light source in your second photo is actually the MOON!?!?
If that is the case then on my screen the photo is great.
However it could also be a deliberately underexposed sun ... then it still is quite an interesting photo!!
Only could this be anywhere ... it does not show that this is Bulgaria and nowhere else.