I notice the transparency of the fog is much clearer when looking at the ground than looking above the traffic. This suggests the temperature profile is such that the air is relatively clear up to about 6 feet height, and then densifies into opaque fog. I suppose this could happen if the ground is warm when the air is cold. I think I have driven in conditions like this, but they are admittedly uncommon.
I notice the transparency of the fog is much clearer when looking at the ground than looking above the traffic. This suggests the temperature profile is such that the air is relatively clear up to about 6 feet height, and then densifies into opaque fog. I suppose this could happen if the ground is warm when the air is cold. I think I have driven in conditions like this, but they are admittedly uncommon.