Why should the eccentricity of Earth’s orbit make winter in the northern hemisphere different from winter in?
The eccentricity of earth’s orbit has realtively little to do with the seasons. As has been already pointed out we’re closer to the sun in January than in July. The earth’s inclination (tilt on its axis) ~23.4 degrees makes all the difference. In the January the sun’s rays are directly over the southern hemisphere causing it to be warm and the northern hemisphere to be cold. In July they’re directly over the northern hemisphere causing it to be warm and the southern hemisphere to be cold. Try this experiment. Set a plate of food directly under a heat lamp for 20 minutes. Observe that the food is warmed. Now move the plate of food off to the side for 20 minutes. Observe that the food has cooled. In the same way the hemispheres of the earth are warmed when the sun is directly over head.
