I have the heat lamp partially above the bowl. It manages to raise the relative humidity to the upper 30's right now. But it does provide a gradient of sorts, the humidity declines as you move to the other end of the enclosure. Winters are really tough on the snakes here, the previous winter the humidity dropped to 18% and they were almost always in the 20's. I don't really have a choice but to provide a "wet box" or keep misting daily. And I don't like the idea of constantly wet surfaces in a terrarium.