sunrise algorithm alt correction

[compressor stall]

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]

Try this link,

http://www.xylem.f2s.com/kepler/sunrise.html#twig03

Hope this is of use.

[compressor stall]

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

[Sheep Guts]

You doing you JAA etxernal ATPL course Stallie?


regards
Sheep

[compressor stall]

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.

[Zeke]

http://imagiware.com/astro/almanac.cgi

[compressor stall]

Thanks Zeke!

[OzExpat]

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...