What is that huge bright white hemispheric thing that appearse at Caspian sea horizon?

Question

Two times in my life (Second time it was around 1990) while being at Caspian sea Iranian beaches, I have seen what I described above that appeared at night, people were all gathered and no one had a clue what it was. Some one saying it was a atomic practice by former Soviet!!
Still after 15 years I don't know what it was. It was small at the begining, then it grew more and more until it was so big it had covered almost the whoe horizon. I doubt any one can help but it worth asking anyways.

Answer 1

Hi. One possibility is that there was a bright city over the horizon and the light was refracted by the right atmospheric conditions. Growing larger could be the conditions changing or the result of your eyes getting dark adapted.

Answer 2

You were hallucinating.