Second this, my mental calendar is a circle, but running counter-clockwise with January 1 at the 12, Feb at 11, etc. I have no problem looking at linear timelines, but viewing these clockwise representations of the year, with January at the 8 position, was surprisingly difficult.
Fascinating! I would have preferred January at the 6 o'clock, with the peak temperature & community interest (Northern Hemisphere at least) at 12 o'clock, and rotating clockwise.
I've always been curious about this -- mine is also counter-clockwise, but with January 1 down around the 7 o'clock position. I've always assumed I imported that from a calendar with aligned seasons (like with the peak of summer at July/August being at the top of the circle), but no real idea of where it originated.
That said, the data is really interesting.