Hours during the day when the sun is above the horizon (horizontally midnight to midnight) throughout the year (vertically January to December) at locations of varying altitude from 90°N (North Pole) to 90°S (South Pole).
Note that for northern and southern places the sun never sets or raises in parts of the year, whereas close to the equator the hours of sunlight hardly change through the year.
White vertical lines mark 6:00/12:00/18:00 of the local time (without daylight savings). Weak horizontal lines show the month boundaries.
The images below show the same for fixed locations:
The underlying calculations of the sun position have been done using the nice and concise code given by
Python Sun Position for Solar Energy and Research | by John Clark Craig | Level Up Coding
(after conversion to Kotlin).