A good science lesson from recently retired Milwaukee meteorologist Vince Condella (a friend of mine from grad school):
It’s that time of year again, one of the great paradoxes of nature. On Wednesday, January 4, at 7:18 a.m. Arizona time, 8:18 a.m. in Wisconsin, the Earth reaches Perihelion, its closest approach to the Sun during the year.
Note in the image Earth’s elliptical orbit around the Sun. Yes, we are 3% closer to the Sun now than we are at Aphelion in July. So why are we closest to the Sun during the coldest time of year? It’s all about the tilt of the Earth on its axis. Our Northern Hemisphere is tilted AWAY from the Sun this time of year, so the Sun is lower in the sky and we receive less direct solar radiation. Just the opposite occurs at Aphelion.
So Happy Perihelion one day in advance! And no, it is NOT a national holiday……although perhaps it should be.😉