If the winter solstice is the longest night of the year, why does it mark the beginning of winter, rather than the very middle of it?

Question

If the winter solstice is the longest night of the year, why does it mark the beginning of winter, rather than the very middle of it?

In: Earth Science

Answer 1

It’s not just the shortness of the day but the length of the night that makes winter. The longer night means there is more time for heat to escape and less time to reheat the land and sea.

This is similar to how ice ages happen. It’s not the coldness of winter but how mild the summers become (due to less axial of tilt). The milder summers can’t melt the ice sheets fast enough so every year ice accumulates until we have an ice age.