When and where should one be able to see (and photograph) the sun set, the sun rise, the moon set end the moon rise without clouds being between the observer and object on the sky?
In order to build a successful “Sun/moon rise/set time, direction and cloud free path calculator” I suggest the following steps:
Add Sun/moon rise/set times to the graphs.
A) Add the (sun day/) night shadow as animation to the map.
B) Same for the moon.
Add lines showing the direction to the sun and moon on the map.
A) Get map data for elivation (hight above sea level) .
B) Projekt the elivation onto the "direktion-to-the-sun/moon-lines.
C) Use the above steps and the curvature of the earth to calculate the distance to the point that the sun/moon will set/rise behind.
D) Use the above and an approximate thickness of troposphere (or better yet, if available, weather data for hights for clouds) to calculate the amount of clouds that the light from the sun/moon have to travel through to get to the observer.
I’ve seen other apps do Step 2 and 3.
(For example, step 3 is done by https://play.google.com/store/apps/details?id=com.andymstone.sunposition
What would be really cool is to see step 1 combined with a weather graph!
And then to see step 2, 3 and 4 be combined with a weather map.
Best of wishes!