Caveman

From Caveman to Chinaman - Cremieux Recueil

Briefly, seasonality is primarily dependent on three factors. The first is the Earth’s tilt, or obliquity, which determines how hemispheres will be tilted towards the Sun in summer and away in winter. The other two factors are lesser-known, but they are nevertheless important. They are the eccentricity of Earth’s orbit, which is how elliptical it is, and the precession, which is about whether the Earth’s closest approach to the Sun happens in the northern or southern hemisphere’s summer season