Re: Condensation

[Paul Hunt <on76@dial.pipex.com>]

>... Warm air can hold a larger amount of water vapor than cold air. 
>Because relative humidity is a measure of how much water vapor is 
>present expressed as a percentage of how much the air can hold, 
>heating the air lowers the relative humidity of the air.  The warm 
>air can now hold more water vapor than the same air could hold when 
>colder ...

... and hence deposits it on the cold windscreen.