Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
Dear Willy, I much enjoyed looking at your diagrams on: http://www.wijzerweb.be/analemmatischengels.html Now consider the following special case... 1. Use the latitude of the Arctic Circle 2. Take a Direct NORTH-facing vertical wall 3. Take the day of the Summer Solstice 4. Assuming a clear sky, for how many hours can sunlight fall on the north face of the wall? This is the theoretical maximum sunlight that a (single-sided) vertical wall can receive in a day. The south side doesn't get so much sun! Your diagram works very well, though some readers may find the Lambert Circle a little surprising in this special case :-) Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
dear Frank and Willy, I share the point of view of Frank, the insolation of a dial may produce unexpected results changing its latitude or its orientation. A dial is enlightned when the sun is above the horizon and when it is above the dial. The sun is above the dial when it is above the horizon of the point where it become horizontal, moving it parallel to itself. I don't know the exact english definition of these coordinates, I might translate it as 'horizontal equivalent point'. To calculate this coordinates is easy: usually we know latitude, declination and inclination of the dial from wich we get substyle angle, elevation angle of the style and substyle hour (or substyle time). The elevation angle is the latitude of the horizontal equivalent point and the substyle hour (misured as an angle) is its longitude. Now it is possibile to calculate the daily arc of the local horizon, centered at noon, and the daily arc of the equivalent horizon, centered at substyle time, their comparison determines the enlighting of the dial and it depends on the sun declination. ciao Fabio Fabio Savian fabio.sav...@nonvedolora.it Paderno Dugnano, Milano, Italy 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2) -Messaggio originale- From: Frank King Sent: Monday, July 02, 2012 4:37 PM To: 'Willy Leenders' ; 'Sundial sundiallist' ; Frank King Subject: Re: a way to determine the period of insolation of a wall, using an analemmatic sundial Dear Willy, I much enjoyed looking at your diagrams on: http://www.wijzerweb.be/analemmatischengels.html Now consider the following special case... 1. Use the latitude of the Arctic Circle 2. Take a Direct NORTH-facing vertical wall 3. Take the day of the Summer Solstice 4. Assuming a clear sky, for how many hours can sunlight fall on the north face of the wall? This is the theoretical maximum sunlight that a (single-sided) vertical wall can receive in a day. The south side doesn't get so much sun! Your diagram works very well, though some readers may find the Lambert Circle a little surprising in this special case :-) Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
Hello Frank, This is an interesting example but I don't quite agree with your conclusion. I estimate the south wall receives 13:20 hours and the north side only 10:40. To draw the analemmatic sundial with Lambert Circles in green and seasonal marker azimuth lines in blue, I use the DeltaCad NASS macro attached. Fer de Vries wrote the original. I hacked it to include seasonal markers as a separate layer. This example also shows that the seasonal marker concept fails at high latitudes. The rise and set azimuth lines no longer converge. Roger Bailey -- From: Frank King frank.k...@cl.cam.ac.uk Sent: Monday, July 02, 2012 7:37 AM To: 'Willy Leenders' willy.leend...@telenet.be; 'Sundial sundiallist' sundial@uni-koeln.de; Frank King frank.k...@cl.cam.ac.uk Subject: Re: a way to determine the period of insolation of a wall, using an analemmatic sundial Dear Willy, I much enjoyed looking at your diagrams on: http://www.wijzerweb.be/analemmatischengels.html Now consider the following special case... 1. Use the latitude of the Arctic Circle 2. Take a Direct NORTH-facing vertical wall 3. Take the day of the Summer Solstice 4. Assuming a clear sky, for how many hours can sunlight fall on the north face of the wall? This is the theoretical maximum sunlight that a (single-sided) vertical wall can receive in a day. The south side doesn't get so much sun! Your diagram works very well, though some readers may find the Lambert Circle a little surprising in this special case :-) Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial hor_analem3SM.bas Description: Binary data --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
I realized I loss the conclusion: I didn't know this graphic method, it is interesting, and 'visual', for the vertical dial. Well done Willy. Fabio Fabio Savian fabio.sav...@nonvedolora.it Paderno Dugnano, Milano, Italy 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2) --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
The original was too large for the size filter. Attached is a small version as a GIF. Regards, Roger From: Roger Bailey Sent: Monday, July 02, 2012 9:09 AM To: 'Willy Leenders' ; 'Sundial sundiallist' ; Frank King Subject: Re: a way to determine the period of insolation of a wall, using an analemmatic sundial Here is a copy of the sketch for those without DeltaCAD. Green are the Lambert Circles for various dates. Blue are the azimuth lines for sunrise and set. The math fails when sunrise and set is at 12, due north, on the summer solstice. The wall parallel is the black line through the date point. This wall line crosses the sundial ellipse when the sun is due east and west as the wall faces due north and south. Regards, Roger -- From: Frank King frank.k...@cl.cam.ac.uk Sent: Monday, July 02, 2012 7:37 AM To: 'Willy Leenders' willy.leend...@telenet.be; 'Sundial sundiallist' sundial@uni-koeln.de; Frank King frank.k...@cl.cam.ac.uk Subject: Re: a way to determine the period of insolation of a wall, using an analemmatic sundial Dear Willy, I much enjoyed looking at your diagrams on: http://www.wijzerweb.be/analemmatischengels.html Now consider the following special case... 1. Use the latitude of the Arctic Circle 2. Take a Direct NORTH-facing vertical wall 3. Take the day of the Summer Solstice 4. Assuming a clear sky, for how many hours can sunlight fall on the north face of the wall? This is the theoretical maximum sunlight that a (single-sided) vertical wall can receive in a day. The south side doesn't get so much sun! Your diagram works very well, though some readers may find the Lambert Circle a little surprising in this special case :-) Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial attachment: Lambert SM.gif--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
Dear Frank, Thank you for the appreciation. Using my method (on an Excel grafic simulation) I see that in the case you describe the insolation period of the north facing wall is: from 0:17 to 6:43 = 6:26 hours and from 17:17 to 23:43 = 6:26 hours = a total insolation period of 12:52 You're right. Never and nowhere a vertical wall can receive sunlight over a longer period of time in a day. 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): http://www.wijzerweb.be Op 2-jul-2012, om 16:37 heeft Frank King het volgende geschreven: Dear Willy, I much enjoyed looking at your diagrams on: http://www.wijzerweb.be/analemmatischengels.html Now consider the following special case... 1. Use the latitude of the Arctic Circle 2. Take a Direct NORTH-facing vertical wall 3. Take the day of the Summer Solstice 4. Assuming a clear sky, for how many hours can sunlight fall on the north face of the wall? This is the theoretical maximum sunlight that a (single-sided) vertical wall can receive in a day. The south side doesn't get so much sun! Your diagram works very well, though some readers may find the Lambert Circle a little surprising in this special case :-) Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
The calculation of Helmut Sonderegger showed me that I should not take the rounded value of 66.5 ° but the exact value of 66:33:33 Then the results are: Using my method (on an Excel grafic simulation) I see that in the case you describe the insolation period of the north facing wall is: from 0:00 to 6:43 = 6:43 hours and from 17:17 to 24:00 = 6:43 hours = a total insolation period of 13:26 You're right. Never and nowhere a vertical wall can receive sunlight over a longer period of time in a day. 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): http://www.wijzerweb.be Op 2-jul-2012, om 16:37 heeft Frank King het volgende geschreven: Dear Willy, I much enjoyed looking at your diagrams on: http://www.wijzerweb.be/analemmatischengels.html Now consider the following special case... 1. Use the latitude of the Arctic Circle 2. Take a Direct NORTH-facing vertical wall 3. Take the day of the Summer Solstice 4. Assuming a clear sky, for how many hours can sunlight fall on the north face of the wall? This is the theoretical maximum sunlight that a (single-sided) vertical wall can receive in a day. The south side doesn't get so much sun! Your diagram works very well, though some readers may find the Lambert Circle a little surprising in this special case :-) Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Fw: a way to determine the period of insolation of a wall, using an analemmatic sundial
I am now in full agreement that the north side of the wall gets more sunshine. When the sun is to the north side of the wall, the hours indicated by the shadow are read on the south side of the hour ellipse. Regards, Roger -- From: Roger Bailey rtbai...@telus.net Sent: Monday, July 02, 2012 8:56 AM To: 'Willy Leenders' willy.leend...@telenet.be; 'Sundial sundiallist' sundial@uni-koeln.de; Frank King frank.k...@cl.cam.ac.uk Subject: Re: a way to determine the period of insolation of a wall,using an analemmatic sundial Hello Frank, This is an interesting example but I don't quite agree with your conclusion. I estimate the south wall receives 13:20 hours and the north side only 10:40. To draw the analemmatic sundial with Lambert Circles in green and seasonal marker azimuth lines in blue, I use the DeltaCad NASS macro attached. Fer de Vries wrote the original. I hacked it to include seasonal markers as a separate layer. This example also shows that the seasonal marker concept fails at high latitudes. The rise and set azimuth lines no longer converge. Roger Bailey -- From: Frank King frank.k...@cl.cam.ac.uk Sent: Monday, July 02, 2012 7:37 AM To: 'Willy Leenders' willy.leend...@telenet.be; 'Sundial sundiallist' sundial@uni-koeln.de; Frank King frank.k...@cl.cam.ac.uk Subject: Re: a way to determine the period of insolation of a wall, using an analemmatic sundial Dear Willy, I much enjoyed looking at your diagrams on: http://www.wijzerweb.be/analemmatischengels.html Now consider the following special case... 1. Use the latitude of the Arctic Circle 2. Take a Direct NORTH-facing vertical wall 3. Take the day of the Summer Solstice 4. Assuming a clear sky, for how many hours can sunlight fall on the north face of the wall? This is the theoretical maximum sunlight that a (single-sided) vertical wall can receive in a day. The south side doesn't get so much sun! Your diagram works very well, though some readers may find the Lambert Circle a little surprising in this special case :-) Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Sundials.org hit by storm
The NASS website www.sundials.org has suffered a significant outage due to the severe thunderstorm that hit the Washington DC - Maryland - Virginia area on Friday, June 29th. The storm ranged from Ohio through West Virginia and into the metropolitan area of DC, Northern Virginia, and Maryland. Our website, hosted by Jack Aubert in Falls Church, VA was hard hit . Power outages have been predicted to run throughout the area until July 7th or later. Please be patient for www.sundials.org to come back on line. Our temperatures still hover in the 100 F (38 C), making conditions extremely hard for many people. My power came on early today and fortunately with it, Internet connection. You can see the storm's damage at: http://www.washingtonpost.com/blogs/post_now Regards, Bob Kellogg NASS webmaster --- https://lists.uni-koeln.de/mailman/listinfo/sundial
