[QUOTE] Carb icing occurs in conditions of relatively high humidity, when there is a lot of water vapour in the air. There's shitloads of sciencebabble akin to a hair conditioner advert about this, but what it comes down to is that as the petrol is atomised it loses heat, chilling the already cold and moist air coming into the carb.[/QUOTE] So does jacket icing. I had a nice thick ish coat of ice on my jacket after my ride this morning.