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 >
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