Determines whether a given UTC timestamp at a given position is during
daytime or nighttime per FAR 1.1 definitions.
FAR 1.1 defines "night" as the time between the end of evening civil twilight
and the beginning of morning civil twilight. Therefore, daytime includes the
civil twilight periods (dawn and dusk).
In polar regions where civil twilight does not occur:
If the sun is continuously above the civil twilight angle, the entire day
is considered daytime (returns true).
If the sun is continuously below the civil twilight angle, the entire day
is considered nighttime (returns false).
Parameters
lat: number
Observer latitude in decimal degrees (positive north).
lon: number
Observer longitude in decimal degrees (positive east).
dateTime: Date
UTC timestamp to evaluate.
Returns boolean
True if the timestamp falls during daytime (including civil twilight), false if nighttime.
Determines whether a given UTC timestamp at a given position is during daytime or nighttime per FAR 1.1 definitions.
FAR 1.1 defines "night" as the time between the end of evening civil twilight and the beginning of morning civil twilight. Therefore, daytime includes the civil twilight periods (dawn and dusk).
In polar regions where civil twilight does not occur: