13:08 Jan 26 

Maybe it's talking about the dirt carried by the fog that leaves dirty lines between the wrinkles on the passers-by's forehead...

18:52 Jan 25 

Could the passers by be walking under a roof or ceiling that has gaps, skylights or even cracks which let in the light? Would that make sense?

17:26 Jan 25 

Any idea why 'fessure' is used here? It's hardly a noun that can be associated with fog, let alone with the heads of passers-by...
As a description, I'd call it obscure...

17:11 Jan 25 

the painter is Caravaggio and I think a little more text would help:D’inverno il giorno si annuncia con una nebbiolina che non tarda a tingersi di un bianco sporco, antico. Tra le fessure che lascia sulla testa dei passanti si aprono ombre amiche che ricordano i chiaroscuri delle tele del Caravaggio. Si dilegua poi lentamente, per lasciar posto a una pioggerellina leggera, come solo può esserlo una carezza. Le montagne circostanti, parte delle Montagne Rocciose che partendo dalla British Columbia vanno a sfumare nel New Mexico, sono sempre coperte di un bianco splendore.

16:49 Jan 25 

We really need to know what comes before this bit. What is the subject of 'lascia'? Are you sure you cannot name the painter's name? There's little we can do here unless we know more.