Earth’s Perihelion

Winter on the northern half of Earth’s globe comes during the southern hemisphere’s summer. Since the Earth is at perihelion during the southern hemisphere’s summer, is the summer there hotter than the northern summer?

Perihelion is our closest point to the sun, and it always comes in early January — this year in the morning on January 3, for Europe and Africa — that’s the night of January 2 for us in the U.S.

And it is the height of summer now in the southern hemisphere — while we’re closest to the sun for this year. So it’s logical to think that the southern hemisphere summers might be hotter . . .

But they aren’t. Of course, the seasons happen mainly because of Earth’s tilt on its axis. Right now, sunlight is striking the northern hemisphere less directly than the southern hemisphere — that’s why it’s winter here, and summer there.

But does our nearness to the sun now make the southern hemisphere summers a bit hotter, on average? The answer is no — because of the greater ratio of ocean to land in the southern hemisphere. The greater expanse of ocean down under helps cancel out any temperature difference caused by our nearness to the sun.

The southern oceans also keep that hemisphere a bit warmer in July — when it’s winter in the southern hemisphere — while the Earth/sun distance is greatest.

What you have in your mind?