Originally Posted by
conspiratemus1
Yes, from mow until the summer solstice, the sun will be up in the evening a little longer every day. The shortest day is not until 21 Dec. but owing to the elliptical nature of the earth’s orbit, the apparent movement of the sun gets enough out of kilter with the clocks this time of year that the clock timing of sunrise, noon, and sunset gets shifted. By Christmas, you will notice the afternoon sun definitely lasting longer.
The downside for those who have to get up early is that latest sunrise doesn’t occur until about 10 Jan. So those post-New Year commutes make for awfully dark mornings.
This “time-shifting” has nothing to do with the seasons per se. It’s just the orientation of the ellipse happens to make the effect strongest in that portion of the orbit that we call December. “The equation of time.”
Is it just us bike commuters that pay this sort of attention to the times of the sunrise and sunset?
I had to ride east in the morning and always tried to adjust my start time to reduce the chance of riding into the sunrise.
The ride home was after peak traffic, so I got to just enjoy the sunsets. Not a bad way to unwind after a day of work!
Back in the early days of the internet, I downloaded a table of sunrises and sunsets from the Naval Observatory's website. I put it into a spreadsheet and plotted it out. That was when it became very obvious that the latest sunrise did not occur at the same time as the earliest sunset. It makes sense that the elliptical orbit accounts for the non-sinusoidal shape of the sunrise/sunset curves, but it's still not clear how that accounts for the different days for latest sunrise and earliest sunset. Maybe there is a video somewhere that explains this in detail??
Steve in Peoria
(I also have a Casio watch that calculates sunrise and sunset time!
)