Cold air from an airconditioner works fastest for clearing a fogged-up windscreen because it has a very low relative humidity compared to the ambient air, and therefore it has a much higher capacity for picking up more water vapour. A windscreen appears fogged up due to millions of microscopic condensation droplets packed on its cold surface. If you don’t have an airconditioner, hot air works better than cold for essentially the same reason: increasing the air temperature also increases the air’s capacity for picking up water vapour. Hairdryers and tumbledryers illustrate this principle.
Now my own question: So, who are the spring chickens?
'Luthon64
"Sensitive" people are now carefully examining the entire universe, trying to find something to be "offended" at. It won't stop until such time as the "offenders" learn to stop apologizing, and saying "freck off" instead. — brianvds, The ShoutBox Classics, 02/07/2018.