How to identify the solar terms ABCD in the northern hemisphere?

This picture first looks at the left picture and the right picture: the North Pole facing the sun is the summer solstice, so C is the summer solstice; The North Pole faces away from the sun, so so does the winter solstice.

Then, according to the counterclockwise direction (the revolution of the earth) and the order of spring, summer, autumn and winter, we can know that B is the vernal equinox and D is the autumnal equinox.

A is the winter solstice, b is the vernal equinox, c is the summer solstice, and d is the autumn equinox.