During the middle of the Eocene, about 40 million years ago...

On Nov 4, 11:06*pm, Sam Wormley wrote:

* *A necessary condition for this angular change is the fact that the
* *rotational axis of the earth is tilted with respect to the normal
* *of the ecliptic by roughly 23.5° .

Once you discover that the reasons behind the 6 months of darkness
followed by 6 months of daylight at the polar coordinates (where daily
rotation is residual) arises solely from the orbital behavior of the
Earth,you are half way to explaining the temperature fluctuations at
lower latitudes where it mixes with daily rotation.As the orbital
daylight/darkness cycle is now common knowledge I had hoped even an
anonymous reader would take a crack at normal language and explain it
to you instead of that robotic statement you just made.