Ice Fog:

The observation room on the IARC buildings fifth floor is high enough to be above most of this particular episode of ice fog.

Ice fog forms when there's a temperature inversion in the area, the temperature drops so low (typically way below zero F) that the very last of the water in the atmosphere condenses into a fog of micro ice crystals.

It can be pretty gloomy down under the fog . . .

. . . . here at least the sun is poking through . . . .

. . . . this raven doesn't seem to be bothered even when it's so dim the street lights start to come on.

Ice fog can result in some really cool sunset effects.

This setting sun is squashed by refraction through the atmosphere (click on the image for a full size image).

This setting sun is squashed too, but it's also distorted by temperature layers in the atmosphere (click on the image for a full-size image).

Sun setting over a sea of ice fog.