William Sidis called it in the 1930’s — and tied revolution to periodic sunspot activity. Revolution is more likely in the north when the sun cools and crops die; revolution in the south is more likely when the sun warms and crops die.
>> Revolution is more likely in the north when the sun cools and crops die; revolution in the south is more likely when the sun warms and crops die. <<
The principal effect being cloudiness vs drought, but the secondary effect is the one being discussed so much lately: global warming. (Obviously, if there are more clouds, it gets cooler.)