Re: Using analemmatic sundials for determining sun exposure times

My guess would be a north-facing wall on the Arctic Circle at the summer solstice, or a south-facing wall on the Antarctic circle at the summer solstice down under. John Lynes On 14 June 2016 at 16:39, Frank King wrote: > Dear Willy and Geoff, > > Good answers but the

Re: Using analemmatic sundials for determining sun exposure times

What am I talking about, I mean 6 months on a vertical cylindrical wall at the north (or south) pole, not a mere 24 hours. Mike Shaw --- https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Using analemmatic sundials for determining sun exposure times

Frank, You only said a vertical wall, not a straight vertical wall, so I'll go for 24 hours on a cylindrical lighthouse wall above (or below) the arctic (or Antarctic) circle. Mike Shaw 53º 21' N 3º02' W ---

Re: Using analemmatic sundials for determining sun exposure times

Dear Frank, I request clarification: Are there limits on the height or length of your wall? I'm thinking of something like Hadrian's Wall, where there is a difference in Local Solar Time between the two ends (but I'd build it longer). Is the wall straight? In particular, does the whole

Re: Using analemmatic sundials for determining sun exposure times

Dear Willy and Geoff, Good answers but the correct value exceeds both your scores. Let's see who else will rise to the challenge before I declare my hand! Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Using analemmatic sundials for determining sun exposure times

Geoff, If you measure the time in true local time (solar time), as I do, the EoT is not relevant. Willy Leenders Hasselt in Flanders (Belgium) Visit my website about the sundials in the province of Limburg (Flanders) with a section 'worth knowing about sundials' (mostly in Dutch):

Re: Using analemmatic sundials for determining sun exposure times

Thanks for the mental exercise, Frank. I think that Willy might squeeze another 15 seconds of illumination at the end of December owing to the rapid change in the EoT. A useful graph showing the rate of change of EoT is provided by the USNO at: http://aa.usno.navy.mil/faq/docs/eqtime.php Geoff

Re: Using analemmatic sundials for determining sun exposure times

See on my website: http://www.wijzerweb.be/analemmatischengels.html The maximum time (12 hours) of sunlight on a vertical wall of any direction is above the Arctic Circle on a day when the midnight sun shines Willy Leenders Hasselt in Flanders (Belgium) Visit my website about the sundials in

Orologi Solari n. 10

Dear friends, Orologi Solari n. 10 is finally available for download from http://www.orologisolari.eu. Here is the list of articles (they are all in Italian but a short abstract is available in English and French): "A Meridian Line at home: Giovanni Battista Amici (1850) Florence" by Paolo

Re: Using analemmatic sundials for determining sun exposure times

Dear Dan, The approach that you describe does indeed show you how long the sun can theoretically shine on a vertical wall, for a given solar declination, provided (as you say) that you know the times the sun rises and sets. Now a simple exercise... What is the maximum amount of time the sun can

Using analemmatic sundials for determining sun exposure times

Hello! An interesting use for an analemmatic sundial which I have only recently read about involves measuring how many hours the sun potentially shines on a given vertical wall. First you draw the analemmatic sundial on paper according to your geographic location. Then you place a ruler on the