[pct-l] condensation on inside of homemade tarptent

[elee at microsoft.com (Eric Lee (GAMES))]

Ilja wrote:
>
I have had condensation in the 2 person tarp tent (with 2 people). Now I

tested it recently alone in the continuous rain (all night) on grass. 
There were little streams running all around the tarp tent. So I doubled

up with a bivy sack. (Not something I would usually carry.) I had zero 
condensation on the tent walls! (Some of course inside the bivy.) Maybe
I 
had enough of an air flow. Or it is the body moisture that normally
causes 
the condensation on the tent walls. So having a VBL might solve the 
problem. Worth experimenting and carrying a thin trash bag.
>

As a general rule, I've found that I get much more condensation when I
pitch my tarp out in the open on a clear night than I do on a cloudy,
rainy night.  The reason being (I think) that on a clear night in the
open the thin fabric easily radiates away its heat to the sky and
becomes colder than the surrounding air, which causes condensation.  If
I pitch the tarp under trees, the problem is much lessened because there
isn't as much heat radiating away.  And if it's cloudy and rainy, I
don't get much condensation either because the fabric is the same
temperature as everything else.

All that to say that I think your success the second time had much more
to do with the weather than with your VBL.

Eric