Quoting Ed Speer:
> Coy, you mentioned something I've also noticed. I often set up my hammock
> and stand in my back yard on the grass where the dew is always heavy and my
> PeaPod is normally covered with frost on cold mornings. I often set up the
> hammock before dark, then don't go to bed til much later--the PeaPod is
> usually covered with frost before I ever get to the hammock (ie, the heavy
> dew from the grass).
When I put up my tarp over the hammock until well after dark, I do not get the
Dew and frost forms because the hammock radiates infra-red heat (IR light) into
a cold night sky. The cloth facing the sky actually gets colder than the air.
I have been able to show this with my IR thermometer. Last night the air
temperature was a balmy 21 F, but the grass out to the side of the hammock was
12 F. The top of the TravelPod was about 15 F except over my waist where the
temperature rose to about 25 F. (Heat loss through the quilt - it was 96 F
inside the quilt and about 25 F outside.)
The dew forms on the hammock or grass in exactly the same way that drops of
water form on the outside of an iced soft drink glass. The glass is cold and
the air right against the glass is cooled by the glass and gives up it's water
content when the relative humidity of the air against the glass reaches 100
percent. Frost forms the same way, except that the water vapor is laid down in
frost crystals instead of water drops.
A tarp over the hammock protects the hammock somewhat from radiant heat loss.
The temperature of the tarp will reach the low teens when it is 20 degrees
outside, but that is quite warm compared with the effective temperature of the
clear night sky... which is something like 60 degrees below zero. So the top of
the hammock does not develop frost (or dew if it is a little warmer.)
Think about it... this is just what happens to a car under a carport. The car
does not develop frost or dew when the "dew can't fall."