Walking above the cloud

It's been foggy in Vancouver since yesterday.
Although the sun has been heating the ground for the entire morning, people still need to keep their headlight on when they drive.
When I headed towards Burnaby campus, I could see the change of the scene.
It seemed that the cloud was much lower than usual, lower to the ground.
If you stand on the mountain, you could clearly see a blue sky and beautiful sunshine.
However, when you look down, the city was covered by fog.
What you see is exactly the same thing as you might have looked down on the ground from an airplane.