- the Sundial App
shows the actual sundial reading right now wherever you are in the world
Instructions for using SNAP! – the Sundial App
1. Go to relativedata.com find SNAP in the menu list on the left hand side, and click on it. The image shown on the left below is displayed
2. Click on the button to the right of “Choose name of country” and select the country you are in
3. Then click on the list of cities.
4. If you find the name of the place you want, click on that. The sundial display changes, with the place name at the top, its latitude and longitude on the next line, and a red line showing the clock time at that location, and a blue line on the top edge of the shadow showing the exact solar time. (If you need an explanation of the difference between the two, please visit www.sundials.co.uk/eot)
5. If you can’t find the name of the place you want, try to find a place to the north or south of it which is on a fairly similar longitude. Then subtract the longitude of the place you want from the latitude of the place shown on the screen. 6. The difference in solar time between your chosen place and the place shown is 4 minutes for every degree of longitude, and 4 seconds of time for every minute of longitude.
7. As an example, Startford-on-Avon (where William Shakespeare was born) at 1:42:30W is not in the list, but Coventry (1:30:41W) is on the list. The difference in longitude is just under 12 minutes of longitude, which translated to 4 X 1 = 48 secs of time. Coventry is to the east ofStratford-on-Avon , so the sun is overhead in Stratford-on-Avon later than it is in Coventry. So the sun time in Stratford-on-Avon is 48 seconds earlier than the time shown for Coventry.
8. The differences (of 48
and 45 seconds respectively)of sun time are unchanged throughout the year.
So if you ever wanted to know the sun time in Stratford-on-Avon at a later
date, you could just look up SNAP! For Coventry (or for Birmingham) and
add the 48 seconds (or subtract the 45 seconds) as above.