Atmospheric phenomena caused by reflected or refracted light in ice particles found in the atmosphere. Time and Date
Half of the globe that is divided by the equator.
Apparent line separating the earth (or body of water) and the sky. Wikipedia.
Horizontal coordinate system
It is a method of defining positions of objects in the sky, such as the sun, moon, stars and planets. It is based on elevation and azimuth position angles originating from the observer. Time and Date
The minimum distance at which the target keeps acceptably focused from the half of that distance to the infinite point. Wikipedia.