Originally Posted by 250 or point 65

Whoa guys. CARB HEAT HAS NOTHING TO DO WITH COLD OAT!

When it's cold outside, the air cannot hold much moisture. You worry most about it when its 50-70 degrees out because that temp air can hold much more moisture than 30 degree air. Also important to note is that carb ice does not have much to do with the venturi in the carb, it has a lot more to do with the heat robbed from fuel atomization. The liquid to gas cooling has a lot of effect on the temp of the air going through the carb.

We were also told a very important story in school about someone who did not understand carb ice. Before taking off in a twin on a very cold day, a guy decides he will use the carb heat before takeoff as a precaution. So what happens is he actually heats the air up to a temp that would cause carb ice, ices up his carb on one side and crashes after takeoff.