On Wednesday, November 1, 2017 at 11:06:47 AM UTC, Martin Brown wrote:



It is the elliptical orbital motion of the Earth around the sun that
makes the solar motion across the sky vary in speed.

Regards,
Martin Brown

This is the statement with the greatest impact in dynamical terms so no offence that I concentrate on this first. The variations in the natural noon cycle greater and lesser than the average 24 hour weekday also shares the same mechanism as seasonal changes.

The principles are based on variable orbital speed which in turn affects the surface rotation as a function of the orbital motion of the Earth. The Equation of Time which registers the natural inequality with each passage of a meridian to noon or midway either side of the circle of illumination (sunrise/sunset) is a global timekeeping correction so no hemispherical declination is involved as the application of the noon correction is common to along locations along a specific meridian line.

The only way to extract the inequality is to isolate the Polar day/night cycles at the poles and construct the Polar day/night cycle in isolation from the daily cycle. The Polar day/night cycle mirrors the daily cycle in terms of sunrise /sunset at the Equinoxes and noon/midnight at the Solstices. Currently the South pole is heading towards noon while the North pole is heading towards Polar midnight.

When the rotation responsible for the Polar day/night cycle is combined with daily rotation at our latitudes, the combination of these rotations create both the natural noon variations and the seasons. It is really lovely weather at the South Pole presently with the acknowledgment that the Sun will remain constantly in view until next March 21st as a means to isolate the polar cycle and the rotation behind it and also why the Equation of Time is necessary to isolate the average 24 hour day which in turn creates constant rotation as a neat trick -

https://www.usap.gov/videoclipsandmaps/spwebcam.cfm

There is no advantage in ignoring the Polar day/night cycle and the uneven rotation parallel to the orbital plane behind it.