💾 Archived View for thrig.me › blog › 2023 › 04 › 23 › seasonality.gmi captured on 2024-07-09 at 01:01:52. Gemini links have been rewritten to link to archived content

-=-=-=-=-=-=-

Seasonality

A teacher once put two of us to the board; the task was to assign the months to the seasons. My thinking went along the lines of "December is pretty cold, that must be winter, therefore winter is December, January, and February." Years later I came to understand that for some spring is defined as starting on the equinox; from that one might derive April, May, and June. This could be a rounding error; one could easily truncate down instead of rounding up. Neither of these triads were very good; we were being taught the Orthodox American System somewhere the seasons ran to three.

"I had three palaces: one for the cold season, one for the hot season, one for the rainy season. During the four months of the rainy season I was entertained in the rainy-season palace by minstrels ..."

https://www.dhammatalks.org/suttas/AN/AN3_39.html

Seattle has a spring that may run as early as late January all through June, based on when things grow. The summer weather shift typically happens somewhere in July. If winter begins in January, that would make the Seattle winter mostly "Winter, when the dandelions grow". Doubtless there is somewhere on the planet where spring begins in April. Some have it worse: Idunn, in the snowstorm. Others center spring on the equinox, which seems less bad, even if it does result in fairly ridiculous poetry.

http://www.wakapoetry.net/kks-i-1/

The Japanese used both the Chinese lunisolar calendar and a definition of spring centered on the equinox, which puts the new year either on what we tag the 4th or 5th of February, or anywhere between the 21st of January and the 20th of February. Or both. The lunisolar calendar does start the year on a new moon, a quality somewhat lacking in the Gregorian system: January 1st is most notable for following December. Likewise, midnight lacks the quality of a day that begins at sunset. Many are asleep for midnight; even if awake, how would they know when midnight is, apart from the glare or noise of a clock? 00:00:00, the time after 23:59:59 (or sometimes 23:59:60, or not).

At Greenwich, the time ball marks the hour after noon, solar noon being another noteworthy event. Noon is less controversial than sunset.

    0 degrees
      Center of Sun's disk touches a mathematical horizon

    -0.25 degrees
      Sun's upper limb touches a mathematical horizon

    -0.583 degrees
      Center of Sun's disk touches the horizon; atmospheric refraction
      accounted for

    -0.833 degrees, DEFAULT
      Sun's upper limb touches the horizon; atmospheric refraction
      accounted for

    -6 degrees, CIVIL
      Civil twilight (one can no longer read outside without artificial
      illumination)

    -12 degrees, NAUTICAL
      Nautical twilight (navigation using a sea horizon no longer possible)

    -15 degrees, AMATEUR
      Amateur astronomical twilight (the sky is dark enough for most
      astronomical observations)

    -18 degrees, ASTRONOMICAL
      Astronomical twilight (the sky is completely dark)

https://metacpan.org/pod/Astro::Sunrise

And what happens when there's a big hill in the way, sometimes? Do you guess where the horizon is? Move to somewhere more suitable for your astronomy? Tweak a mathematical horizon to account for subsidence from soil loss over time? Firehose the hill? Most probably shrug and make do.