sunrise
The sunrise method returns an Instant representing the elevation adjusted sunrise time. The zenith used for the calculation uses geometric zenith of 90 plus AstronomicalCalculator.getElevationAdjustment. This is adjusted by the AstronomicalCalculator to add approximately 50/60 of a degree to account for 34 archminutes of refraction and 16 archminutes for the sun's radius for a total of 90.83333˚. See documentation for the specific implementation of the AstronomicalCalculator that you are using.
Return
null if sunrise can't be computed (see getUTCSunrise). Otherwise, the Instant representing the exact sunrise time. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, a null will be returned. See detailed explanation on top of the page.