Equinox

Sunrise: 06:24, Sunset 18:24. Later today the sun passes over the equator, en route to Northern Hemisphere summer[1].

And indeed, after a winter characterised by unusually cold nights and the first real snow since I returned from Italy in 1998, spring is upon us.  It’s getting rapidly warmer, even within the timescale of the week, though cloud yesterday looked like possible rain after several weeks of bright sunshine.

Another sign of spring is a burst of bright colours from the spring flowers, now out in force.  But though the March flowers are happy, not everything is well.  The local tree that normally blossoms in February or even January is looking sick, probably having suffered from the winter.

[1] Unless, that is, I am misled by misinformation or some aspect of terrestrial asymmetry.  I don’t know exactly what those published sunrise/sunset times represent, bearing in mind that the sun appearing/disappearing over the horizon is not instantaneous.

Posted on March 17, 2010, in seasons. Bookmark the permalink. 2 Comments.

  1. Figures. It’s getting positively cool down here. I actually put on a dressing gown, when I get out of bed, for more than just modesty now.

    Enjoy your summer. It hasn’t completely gone from here yet, but I figure it’s only a couple more weeks before autumn sets in in earnest.

  2. Good question in that footnote, and Google finds that the nmm.ac.uk says:
    ————-
    Sunrise and sunset

    The times of sunrise and sunset refer to the times when the Sun’s upper limb, as affected by refraction, is on the true horizon of an observer at sea-level. This occurs when the Sun’s centre is 50 arcminutes below the true horizon, the upper limb then being 34 arcminutes (just more than the Sun’s apparent diameter) below the true horizon.
    ————–
    So they are assuming some sort of standard atmospheric refraction for the purposes of forecasting the time. So when you are at sea level with normal refraction sunrise and sunset denote the times between which you can see any part of the sun (if I understood it correctly). Comments about physicists and spherical horses running in vacuums not required.

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