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Why is it winter in the north when it's summer in the south, and vice versa?

I know the standard answer to this question is "because of the Earth's axial tilt, at a point in the Earth's orbit where the northern half is inclined towards the sun, the southern half is inclined away from it and so they get less sunlight," but the more I think about this question, the more it feels like an oversimplified "lies told to children" answer.

This explanation would make perfect sense if the Earth's orbit were perfectly circular, but it's not. According to Wikipedia, the difference between the perihelion and aphelion of Earth's orbit is approximately 4 orders of magnitude greater than the Earth's radius. This seems to suggest that the difference in insolation from the entire planet being closer or further away from the sun ought to completely dwarf the difference from one half of the planet being further away than the other half and render it negligible, and therefore we should all have summer and winter at the same time.

Why is this not what happens?

Mason Wheeler
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    The correct comparison is the fractional change of the peri-ap difference to the distance to the Sun. The difference in insolation is insignificant when compared to the difference due to tilt. – garyp Feb 13 '19 at 16:20
  • Also relevant: https://physics.stackexchange.com/questions/114243/the-reasons-of-seasons-on-earth?noredirect=1&lq=1 – Gimli Feb 13 '19 at 16:33
  • Please take the answers to these questions also into account and reformulate yours accordingly if it is not answered there. – Gimli Feb 13 '19 at 16:34
  • You may also want to investigate the seasonal effect of the land mass asymmetry and pollution asymmetry--all affect clouds and hence albedo, but that is much more complicated than saying $(94/92)^2 \approx 1.04$. – JEB Feb 13 '19 at 16:36
  • The peri-ap difference does make our southern hemisphere seasons more extreme than at equivalent latitudes in the north, but there are other factors too, like our circumpolar current, and no equivalent to the wide Eurasian landmass. – PM 2Ring Feb 13 '19 at 17:08

2 Answers2

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Earths tilt makes the greatest impact on the ammount of sunlight that a given surface area absorbs and it is not because when tilted, that part is closer...It is because when tilted towards the sun, northern part receives more direct sunlight because of the angle. More sunshine hits the surface. When on the oposite side southern hemisphere is tilted towards the sun so it then receives more sunlight. It is the angle, not the distance...

Žarko Tomičić
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    Like a flashlight at an angle, the illumination per square meter is decreased by the cosine of the angle. – PM 2Ring Feb 13 '19 at 17:02
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The effect of the change in the Earth's distance to the sun on the amount of heat the Earth receives from it is negligible when compared to the real reason for the seasons, the changing length of day. The changing length of day is caused by the 23 degree tilt in the Earth's axis meaning at one extreme the Northern hemisphere has long days and the Southern short days and at the other extreme vice versa.

Ashandy
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    It's not just the daylength, though. In summertime, the regions near the pole have very long days, but it's warmer in the regions closer to the equator, where the daylengths aren't quite as extreme. – PM 2Ring Feb 13 '19 at 16:33