| Forum Home | ||||
| PC World Chat | ||||
| Thread ID: 59455 | 2005-07-03 05:52:00 | sundials / Nth. Hem & Sth. Hem | mark c (247) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 368896 | 2005-07-03 05:52:00 | Is a sundial different in the northern hemisphere to the southern hemispere? Er, I can't quite think straight. They both point to the north at midday. or rather the angled bit in the middle does. I know they can be adjusted to latitude or you can calculate the adjustment yourself like the one in the Town Basin in Whangarei. I kind of think you ask people and nine out of ten wouldn't know if they were different in the northern Hem. to the southern. :confused: person...........m (one of the nine) :help: |
mark c (247) | ||
| 368897 | 2005-07-03 05:58:00 | The shadow goes clockwise in the Northern hemisphere, Anticlockwise in the Southern hemisphere. The "Gnomon" points in the opposite direction as well. |
godfather (25) | ||
| 368898 | 2005-07-03 06:10:00 | OK so a sundial designed for the northern hemisphere would show the wrong reading in the southern? All the numerals would be back to front? Thanks GF. :) |
mark c (247) | ||
| 368899 | 2005-07-03 06:21:00 | liftoff.msfc.nasa.gov | godfather (25) | ||
| 368900 | 2005-07-03 06:26:00 | Terrific, thanks again . (think I'll build one now . ) :) |
mark c (247) | ||
| 368901 | 2005-07-03 06:38:00 | Terrific, thanks again . (think I'll build one now . ) :)Goodluck finding the sunshine to run it! :p |
Jen (38) | ||
| 368902 | 2005-07-03 06:50:00 | And remember to turn it off when not in use . They use a lot of energy . . . |
godfather (25) | ||
| 368903 | 2005-07-03 06:58:00 | Sunshine's not a problem as I live in the winterless north. Energy consumption I already thought about. I'll make the gnomon removeable. :D |
mark c (247) | ||
| 368904 | 2005-07-04 05:19:00 | The simplest dial to construct is the equatorial (www . as . utexas . edu/mcdonald/scope/poster/sundial . pdf) . That demonstration model is for the northern hemisphere . Just change the numbers . It has the advantage that if you make the dial rotatable you can adjust it for both the permanent 1/2 hr offset (because NZ isn't at 180 degrees longitude) and daylight saving . The Equation of Time will always be a problem (or as long as the earth has a wobble) . The hour divisions are exactly 15 degrees which saves some calculations . You do need two dials on both sides of the panel, one for each half of the year . That's much more convenient at our latitudes than nearer the poles . |
Graham L (2) | ||
| 368905 | 2005-07-04 06:53:00 | That's very interesting Graham L. Thanks for the link, and the info. Build a better sundial the world will make a path to your door. :D I like the adjustment factor. Cheers..........m I plan to mount a small solar panel to drive a fountain pump for my pond on the same post so will have the ancient and modern together. :) P.S. As to the puzzle about the two hemispheres it suddenly struck me. How many times have I heard / seen Nth. Hem. properties being praised because the garden was 'south facing'. So the sun and shadows are all opposite to us. Tch. |
mark c (247) | ||
| 1 2 | |||||