Why do you experience a higher evaporation rate in colder temperatures even if the humidity is 100%? Here's an explanation without being too technical.
Relative humidity (the humidity seen on weather reports) is exactly that, relative. Relative humidity is qualitatively how much water vapor that is in the air relative to the total amount of water vapor the air can hold at a given temperature.
A reasonable approximation is to say cold air can hold less water vapor than warm air. So an airmass with 100% relative humidity on a 30F degree day has much less water in it than an airmass with 100% relative humidity on a 80F degree day. Why that's important in second.
But if the air is saturated, that is the relative humidity is 100%, how can I still evaporate anything?
The relative humidity of 100% is at a given temperature, the temperature from the weather report. When you boil, generating heat, the cold ambient air and hot air coming off your boil mix, resulting in air that is warmer than the ambient weather report. Now remember the warm air can hold more water vapor than cold air. Your mixed warmer air that was saturated at 30F (relative humidity 100%) is now say 90F, is far from saturated (low relative humidity, in fact if you added no moisture to that air, the relative humidity would be 11%). But that mixed air doesn't have 11% relative humidity, it 'picks up' moisture from your brew pot via evaporation.
Now if your ambient air was 70F there is less of a difference in the total amount of water vapor the ambient air and heated air can hold and there will be less moisture 'picked up' from your brew pot....aka lower evaporation rate.
Bottom line, the larger the difference between the ambient air temperature and your boiling temperature the larger the evaporation rate will be.
Yes more wind will increase evaporation rate some due to more efficient mixing of air. The relative humidity also has an impact (greater impact at warmer temperatures, when ambient and boiling temperature difference is less), but overall the RH impact is far less than the difference attributed to the temperature difference between the ambient air and the boiling temperature.
A couple items to chew on:
100% relative humidity at 30F = 11% relative humidity at 90F
Consider two airmasses with 50% relative humidity at 40F and 90F.
The one at 90F as 600% more water vapor in it than the one at 40F.
*All this assumes sea level pressure. There are altitude concerns.........ie lower pressure in Denver, that has an impact too, but we'll let those Mile Highers out there worry about that.