Revised 10 September 2018
Most individuals are in all probability unaware of this however the size of a photo voltaic day, which is the pure day measured by the rising and setting of the Solar isn’t at all times 24 hours. It varies barely all through the course of the 12 months and that September 18 is actually the shortest photo voltaic day within the 12 months. This submit discusses this curiosity, which isn’t extensively recognized.
Background- the variation within the size of the day.
Though a day for sensible timekeeping functions is at all times 24 hours, the precise size of a photo voltaic day, which is the time distinction between two successive events when the Solar is at its highest within the sky, varies all year long. As proven within the graph beneath, it’s at its longest, 24 hours 30 seconds, round Christmas Day and is at its shortest, 23 hours 59 minutes 38 seconds, in mid-September.
How the size of a photo voltaic…