Tarp question

[Joe Clement]

I used a MLD tarp I bought here for the first time this weekend, and was surpised to find condensation on the inside of the tarp. Is that normal? It was 85% humidity, instead of our normal 20%, but I was surprised. My bag stayed dry, so I don't guess it matters, it just surprised me.

[Thomas Burns]

Ah, something I can comment on with the authority of an observatory director responsible for keeping a telescope condensation free.

Contrary to popular opinion, dew does not fall. It condenses when the temperature falls to the dew point. At 85-percent humidity, the temperature doesn't have to fall that far to reach the dew point, and moisture will condense on every available surface, up or down.

Add to the mix . . . you, a veritable Grundlage of extra H2O, and you have condensation. I have frosted up telescope eyepieces just by putting my eye near them. Our snores are even worse moisture producers. Even with good ventilation, without a strong evaporative wind, high humidity and a human presence are bound to produce condensation.

I keep my bandana handy to wipe it off if it's dripping on me — or I just leave to live with it if it isn't too cold. The biggest problem is turning over into the tent wall. That's why I like my Tarptent Moment, which has mesh barriers to protect the head from getting wet.

Stargazer

[Jim Colten]

Seeing that you live in a region where "water problems" are most often not having any (as opposed to having an excess) it DOESN'T surprise me that you'd be surprised!

But condensation over, under, around and through a tarp sure is normal in the eastern half of the country. I was surprised when we had no condensation on our TarpTent Friday and Saturday night … very rare for us.

Here's a story from an acquaintance who went to school in Houston: He had a friend who was a native to the area and moved from there to San Antonio. Was amazed to see water evaporate!

Condensation is a manageable condition in my region (upper Midwest) .. just be a little careful about what touches the tarp, shake off as much water as you can before packing it and hang to dry when you get home. I'm not sure about that in regions where the dew is so heavy that it flows off the tarp most nights.

[Joe Clement]

Thanks for the responses. It wasn't a problem, I just watched it run down and drip off. Just surprising. Of course, I think my kids didn't see rain until they were 2 years old too..

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