Subhan Allah take a look at the London fog today, all the city covered.

12200647 1645439549078847 895791219 n?oh1fea66e4aefce1637bbd2c70ca3c3d76&ampoe5638FD51 - Fog in Islam

This made me think, is there anything else in Islam related to fog? The wisdom behind why Allah does it?

Of course it's one of the signs of Qiyamah, "The fourty day smoke/fog".

Fog or smoke will cover the skies for forty days. The non-believers will fall unconscious, while Muslims will be ill (develop colds). The skies will then clear up.
But has anyone found any other knowledge on it?