Re: a way to determine the period of insolation of a wall, using an analemmatic sundial
Dear All, I am delighted that so many readers explored the amusing problem of how long the sun can fall on a north-facing wall. I liked the diagrams that Roger and Helmut prepared. The different approaches led to much the same answers, including Roger's once he had looked at the correct side of the wall! Willy says: You're right. Never and nowhere a vertical wall can receive sunlight over a longer period of time in a day. Helmut adds: Further on the pdf shows that the maximum of sun on a south wall is 12:00 hours but, at equinox not on summer solstice. This needs interpretation... For the maximum sun on a vertical *south* wall you have to place it on the ANTarctic circle where you get the same answer! Helmut is right that a south-facing wall gets 12 hours of sun at an equinox. This is true for any south-facing vertical wall in the northern hemisphere. You won't get 12 hours on the south side in the southern hemisphere! Alas, here it is raining so no sun at all, and in half an hour I am leading 20 visiting academics on a sundial walk walk:-( Enjoy the sun if you have it! 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
Few people know that a north-facing sundial is useful. They are quite surprised that the insolation time of a north-facing sundial in summer (summer solstice) may be as long as the insolation time of a south-facing sundial in winter (winter solstice). This is the case at 53 ° 18 'N. For example, - in Bedum, 9 km north of Groningen (Netherlands) - in Marxen, 18 km south of Hamburg (Germany) -near the motorway junction of the A41 and the M53, 12 km south of Liverpool (Great Britain) - in the north of Lake Winnipeg in Canada. 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 3-jul-2012, om 11:03 heeft Frank King het volgende geschreven: Dear All, I am delighted that so many readers explored the amusing problem of how long the sun can fall on a north-facing wall. I liked the diagrams that Roger and Helmut prepared. The different approaches led to much the same answers, including Roger's once he had looked at the correct side of the wall! Willy says: You're right. Never and nowhere a vertical wall can receive sunlight over a longer period of time in a day. Helmut adds: Further on the pdf shows that the maximum of sun on a south wall is 12:00 hours but, at equinox not on summer solstice. This needs interpretation... For the maximum sun on a vertical *south* wall you have to place it on the ANTarctic circle where you get the same answer! Helmut is right that a south-facing wall gets 12 hours of sun at an equinox. This is true for any south-facing vertical wall in the northern hemisphere. You won't get 12 hours on the south side in the southern hemisphere! Alas, here it is raining so no sun at all, and in half an hour I am leading 20 visiting academics on a sundial walk walk:-( Enjoy the sun if you have it! 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
Willy, They are quite surprised that the insolation time of a north-facing sundial in summer (summer solstice) may be as long as the insolation time of a south-facing sundial in winter (winter solstice). This is the case at 53 ° 18 'N. For example, -near the motorway junction of the A41 and the M53, 12 km south of Liverpool (Great Britain) A very useful fact for me to know, as I live at 53º 22’ North, quite close. In fact, 5.9 miles from the junction of the A41 and M53. Mike Shaw 53º 22'N 03º02'W www.wiz.to/sundials - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2193 / Virus Database: 2437/5108 - Release Date: 07/03/12 --- 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 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
a way to determine the period of insolation of a wall, using an analemmatic sundial
On my website I describe the analemmatic sundial and some posibilities of this type of sundial. Inter alia, the Lambert Circle, and thereto is added a way to determine the period of insolation of a wall, using an analemmatic sundial. For these two descriptions I made a separate English translation and put them on my website at this address: http://www.wijzerweb.be/analemmatischengels.html The full page about analemmatic sundials, although in Dutch, you'll find at this address: http://www.wijzerweb.be/analemmatisch.html 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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: a way to determine the period of insolation of a wall, using an analemmatic sundial
Very elegant! It would be interesting to build a mechanical model with a moveable rule for the wall line, for field checking. Dave _ From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Willy Leenders Sent: Sunday, July 01, 2012 11:54 AM To: Sundial sundiallist Subject: a way to determine the period of insolation of a wall,using an analemmatic sundial On my website I describe the analemmatic sundial and some posibilities of this type of sundial. Inter alia, the Lambert Circle, and thereto is added a way to determine the period of insolation of a wall, using an analemmatic sundial. For these two descriptions I made a separate English translation and put them on my website at this address: http://www.wijzerweb.be/analemmatischengels.html The full page about analemmatic sundials, although in Dutch, you'll find at this address: http://www.wijzerweb.be/analemmatisch.html 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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
