Fog that descends with night has always seemed of a character different from the fog of dawn. They are the same to a meteorologist but the metaphors are distinct.
With night comes the end of processes and pursuits, the descent into sleep and the loss of consciousness. Hence the metaphor of a foggy brain or of one’s mind in a fog is a negative image, a smothering of vitalities. It has nothing to do with night people or owls who enjoy late night reading or music or reflection. These insulate the self from the night, make it a context. They do not live in the night but, in a sense, outlast it, until sleep comes inevitably.
But the fog that seems to emerge with the first light of dawn is a bridge to awakening and consciousness, a promise of brightness, a clear and cooling metaphor for gradual enlightenment. (It can accommodate sudden enlightenment, too, as when one moment there is fog and the next there is nothing but absolute clarity.) The scintillating moments when night begins to ebb and fog reveals itself pulling away from the thick edges of darkness show how independent is fog. The ambiguity and flexibility of fog at dawn is a reminder of how everything gradually reveals itself, that it is not the harsh light but the gentle realization of perception and pattern that gives meaning and insight.