Talk:Hallownest/@comment-3302608-20180716224252/@comment-36029834-20200411232012

There's a lot that we don't know or understand about the wider world of Hollow Knight; but I'd say the most likely practical/realistic reason would be that it's a larger cave, as you mentioned.

In terms of Lore however... It might be worth noting that In the Land of Storms we learn that the gods of Storms and Rain are dead; and we never encounter lightning or genuine rain within the game. Perhaps the Higher Beings have major influence over their element. The Radiance fight takes place amid imagery of clouds, with her as the sun, so the Radiance having been sealed (and/or eventually killed) could explain why there's no sunlight. The alternative Pale Light (Pale King = the moon...?) has also died, so there's not really any heavenly light to go around anymore.