Winter Solstice Sunset and Sunrise Times
The winter solstice arrives every year on December 21 or 22. However, for mid-northern latitudes the date of earliest sunset is almost two weeks earlier, on December 7. Likewise, the date of latest sunrise is later, about January 5. Why? Short Answer: For most of the year the rapidly changing number of Daylight Hours determines whether sunset is earlier or later than the day before. But as we approach the Solstice on December 21 the Solar Day 24 (amount of time between successive zenith crossings of the Sun, approximately 24 hours) becomes more important and pushes the time of sunset later. Larger than average Solar Day 24 wins the battle with shrinking Daylight Hours on December 7. A similar interaction combines to push the date of latest sunrise to January 5. Details: If the Earth’s orbit around the Sun was a perfect circle, and the Earth’s axis was not tilted with respect to its orbit, then latest sunset, earlie...