Literal uses:
* The fog rolled in so thick we couldn't see the road ahead.
* The fog cleared as the sun began to rise.
* The city was shrouded in a thick fog that morning.
Figurative uses:
* The fog of war made it difficult to understand the situation.
* Her mind was clouded with fog after the accident.
* The scandal cast a fog over his career.
Let me know if you'd like to see more examples!