I am very often "in the fog" when trying to fully grasp concepts conveyed by neurologists, and others in their papers and books.
I’m used to being there though
. Perhaps you will think it is carrying the metaphor too far to say that sometimes clarity is brought about by the fog itself. This is true in more ways than one, but sometimes we don't even need to employ the metaphor...
...we only need to "listen"
Fog acts as an attenuator... a sound-deadening medium.
It is a very thin sound-deadening medium, so sounds that are relatively near you are attenuated very little. In fact, the amount that nearby sounds are reduced may be so small, that the deadening effect on them is imperceptible.
Fog is also an evenly distributed attenuation medium. In other words, the deadening effect of 100 meters of fog is exactly half the deadening effect of 200 meters of fog.
This would be kind of boring, except that the sound it is deadening is a point-sourced phenomena. Like light, sound's intensity reduces at the rate of "1 over r squared", where r is the distance that the sound has traveled from the source.
This combines with fog's even attenuation-effect to produce an environment where the background noise normally present as a result of distant sounds has been steeply attenuated, while relatively nearby sounds reach you almost unchanged.
The effect is clarity. You hear every sound around you clearly, and seemingly isolated, as if it had been spoken in a library.
There is also a very non-intuitive perception that the fog is actually an amplifier: that it lets you hear sounds from far away. These farther-away sounds aren't amplified by fog, instead, they are no longer masked by the every-day noise from sources that are even farther out. That is, these sounds that seem amplified are those that are a little farther away, which you would not have normally heard over the din from a thousand more distant sounds filling your ears. The slightly closer sounds become clearer because the sounds from the very distant sources are all silenced by the fog.
P.S. Let's not forget about the clarity we all got from cloud-chambers back in the 1920's (thanks Mr. Wilson).