Condensation during cold smoking
Warm air can hold much more water vapor than cold air
1 kilogram of air at 5 degrees Celsius can contain a maximum of 5.7 grams of water vapor. If it is 25 degrees Celsius, 1 kilogram of air can contain up to 20 grams of water vapor. Or to put it another way: if you increase the temperature at the same amount of water vapor per cubic meter of air, the air will become a lot drier. (relative air humidity)
We call this physical phenomenon the maximum vapor pressure.
The maximum vapor pressure of a liquid at a given temperature is equal to the saturated vapor pressure of the liquid at that temperature.
When steam (= warm) condenses (= cools) then you get condensation = liquid.
There is also condensation on a cold glass of beer on a hot summer day.
If you are going to cold smoke with an outside temperature where the humidity is so high that the saturated vapor pressure has been reached, then you only need small temperature fluctuations to get condensation on a slightly colder surface, (lid of your smoker / BBQ)
Mist occurs at different temperatures, high and low and that just means that the saturated vapor pressure of water has been reached at that temperature. (Relative humidity is very high, 100%)
Cold smoking if it freezes well for a few days, then you will hardly suffer from condensation, after all, the icy air is very dry due to the frost and therefore contains little water vapor.
If the dry air heats up without the presence of moisture, the air will only become drier and there is no chance of condensation if it encounters a colder surface.
This happens in practice:
Air with temperature X saturated with water vapor enters your smoke barrel and is burned by the smoldering smoke moth and heated slightly, so it can absorb a little more water vapor that is present in the environment, the air rises and encounters the cold lid, causing the air again. cooling down, he can no longer retain the water vapor absorbed that this air had absorbed after heating by the smoke moth, since the air was already saturated with water vapor when it was still colder.
this extra absorbed water vapor during heating must therefore let go of the air again and will deposit on the lid as condensation.
As long as the relative humidity is low and the cool air can warm up and cool down again without becoming saturated with water vapor, everything is fine, without condensation.