View Full Version : sunrise algorithm alt correction
compressor stall
30th Jul 2003, 12:47
Trying to work out an excel spreadsheet that compensates sunrise sunset times for the effect of the observer's altitude.
I have Ed Williams Avformulary but that's for sea level...
Any pointers?
MaxBraking
31st Jul 2003, 07:11
Try this link,
http://www.xylem.f2s.com/kepler/sunrise.html#twig03
Hope this is of use.
compressor stall
31st Jul 2003, 09:18
hmmm, thanks for the link...the required altitude there seems to be teh altitude of the sun (-6deg for civil twilight etc) not the observer sitting in a plane or on top of a tall mountain.
is there any way of easily calculating it from say 16000 feet...i think I'll have to calculate the distance to horizon from height and go from there :confused:
Sheep Guts
31st Jul 2003, 10:52
You doing you JAA etxernal ATPL course Stallie?
regards
Sheep
compressor stall
31st Jul 2003, 11:19
Nah sheep, actually its for calculating sun rise and sets for the summit of a 14000 foot active volcano in a very remote part of the world where we'll be doing some video and still photography of some ski-mountaineering next April.
It's also of academic interest to me as a pilot in the flight levels...and another little equation to play around with on long sectors. :D
http://imagiware.com/astro/almanac.cgi
compressor stall
3rd Aug 2003, 20:56
Thanks Zeke! :ok:
OzExpat
4th Aug 2003, 16:51
Hey Stallie, I've found this to be true just about everywhere... when the pics and videos come out too dark, it means they were taken at night... :O