Fog can have symbolic meaning. Fog is a visual aspect that can creep into your sub-conscious.
The “fog of war” is used to describe that which is not known until the smoke clears.
But you can see some things through the fog. A momentary vision partially obscured is like a dream only partially remembered. Descriptions of fog are used by novelists to create a feeling of mystery, think Sherlock Holmes, in the readers mind.
Let’s take it a step further. Fog can create a sense of fear. If walking through thick fog one never knows if one might unsuspectingly fall off the face of a cliff. If the windshield of one’s car fogs up one might drive into a truck head on, unsuspectingly. The drug induced fog in one’s mind might cause one to forget who they they are, or others.
Fog can be burned off by the sun or be blown away by the wind. It can descend upon a sleepy town or blanket the low lying hills. Fog can drift in or disappear.
Fog is a vapor, a steam or a kind of smoke. It can be billowing or passing through. You can go through the fog or avoid it altogether.
Fog can be your friend if you want to remain unseen or your enemy if you are hunting someone or something down.
When the fog has lifted, however, everything becomes clear again.