Quote Originally Posted by Physician&Snakes View Post
The above poster has given accurate information, I do have one thing to add though. Humidity sinks in proportion to heat, which rises . Therefore, a damp towel at the top of the screen is going to be slowly distributing humidity that is almost immediately pushed back into the towel or through it to the outside, meaning most of the outputted humidity is not getting to the cage floor, where your snake is most likely to be. For this reason, I saturate my substrates on a weekly basis and allow them to dry throughout the weekly so that humidity is highest at the floor and lowest near the top. So, a towel may work, but it is largely inefficient compared to a well saturated substrate.
Agree! If you only need a slight humidity raise (such as when my corns are going through a shed cycle) a damp towel usually does the trick for a couple of days, but for long term use plastic wrap or plexiglass to cover 50-70% of the screen to prevent humidity from escaping. You can damped the substrate, but also make sure you don't keep *too* wet or else you risk your snake developing scale rot on their stomach.

Good luck!