water bottle question for cooler incubator

I was wondering why, in every DIY cooler incubator thread, did all the water bottles have lids on them? How does the humidity transfer from the bottles to the rest of the surrounding inside the incubator? Thanks

The water bottles are not for humidity. They are to help keep a stable temp. Once they warm up they will help to keep the incubator from getting as bad of temp fluctuations...

Aaahh, I see I see. Thanks very much

Not a problem....Anytime...:D

Most incubators are built to not have any humidity in the bator itself. Temps are controlled in the bator and humidity is controlled inside the eggbox. Water bottles will also help a little at holding temps during a power outage. Shorts periods of time granted, mainly used as mentioned above, as a stabilizer.