Article 16199 of alt.solar.thermal: Path: news.misty.com!not-for-mail From: nick@acadia.ee.vill.edu (Nick Pine) Newsgroups: alt.solar.thermal Subject: Re: Solar Shower for sunny days Date: 26 Sep 2003 21:11:49 -0400 Organization: Villanova University Lines: 15 Message-ID: References: <3f74b758.5435571@news1.on.sympatico.ca> NNTP-Posting-Host: acadia.ece.villanova.edu X-Trace: news.misty.com 1064625115 17461 153.104.63.246 (27 Sep 2003 01:11:55 GMT) X-Complaints-To: abuse@misty.com NNTP-Posting-Date: Sat, 27 Sep 2003 01:11:55 +0000 (UTC) Xref: news.misty.com alt.solar.thermal:16199 Down Under On The Bucket Farm wrote: >Can anyone explain the reason for those "solar/camping" shower bags >being half black-coloured and half clear? Intuitively, I would expect >all black to absorb better, but perhaps that isn't the case? Perhaps it makes little difference whether a vertical (vs horizontal) surface in contact with water is black or clear, because the film-to-water thermal conductance is 40X greater than the film-to-air conductance. Then again, it may help avoid temperature stratification. A clear "solar pool cover" can be a lot more effective than a black one, since the downward heat conductivity of water is small. Nick