Water droplets in the fog or mist make light scatter a lot more than it would otherwise. This greatly softens light, but also makes light streaks visible from concentrated or directional light sources. The classic example is the photo in a forest with early morning light: when the photo is taken in the direction of this light, rays of light streak down from the trees and scatter off of this heavy morning air. I call this effect an explosion of light - I have managed to make a few spiritual images lately and I really like this one; I love these calm mornings they somehow boost my energy and I feel happy.
(Nikon D700, Nikkor VR 70-200/2,8 II, iso 200, handheld)