wow, it’s hard to prevent condensation under a tarp

Tent or tarp, you're going to get condensation. With science and all you can try to keep it away but the inside of tarps just get wet.

I just learn to live with it. If it's to the point of drips you can carry a small sponge and just brush it a few times a night. Or lay your rain gear or something else over your down sleeping bag if becomes a problem. Stay dry!

Acronym,

Thanks for the link to the article (http://johncwalton.com/WindowOutdoors/Dew%20Frost%20Condensation%20and%20Radiation.htm).

This helped me understand things a bit better.

I've noticed for some time that I get very little condensation on the inner tent if I am in a small inner tent with a fly. The fly gets plenty of condensation, however. From the article I think it is because I can keep the interior of the small inner tent 10-25 degrees warmer than the outside air.

I've also noticed that coated bathtub floor walls of an inner tent will get less condensation if they hang from the inside of the inner tent walls than if they hang directly below the inner tent walls. That double layer of nylon, again, keeps the bathtub floor wall warmer than the single layer of fabric that is typical for bathtub floor walls.

Daryl