B North and South poles of Mars are at different temperatures?

[sophiecentaur]

The images I have seen of Mars seem to show a more pronounced polar 'ice' cap on the South Pole than at the North. Could that be something to do with the times in the Martian year that the images are all taken (relative orbital positions vs winter and summer) or something else?
Earth's South pole has more of a permanent ice cap but that can be explained by the solid ground of Antarctica vs the sea under the North pole. But there isn't an equivalent difference on Mars.
Any ideas?

 

[CygnusX-1]

According to Magnificent Mars by Ken Croswell, page 72: "Mars is nearest the Sun just before the start of southern summer, so southern seasons are the more severe." So southern summers are warmer and southern winters are colder.

 

[mathman]

According to Magnificent Mars by Ken Croswell, page 72: "Mars is nearest the Sun just before the start of southern summer, so southern seasons are the more severe." So southern summers are warmer and southern winters are colder.

On earth, the seasons of the northern hemisphere are opposite that of the southern. In the quote which hemisphere of Mars is being referred to?

 

[CygnusX-1]

The southern.

Mars is like Earth in that northern winter coincides with southern summer, and as the quote says, Mars is nearest the sun just before the start of southern summer.

 

[sophiecentaur]

According to Magnificent Mars by Ken Croswell, page 72: "Mars is nearest the Sun just before the start of southern summer, so southern seasons are the more severe." So southern summers are warmer and southern winters are colder.

That could make sense; the more elliptical the orbit, the greater would be this effect.
This leads to the question why the tilt of the axis (Earth's too) happens, coincidentally to line up with the major axis of the orbital ellipse. Is there some sort of locking mechanism at work or is it just luck. Or, is it to do with the geometry and timing of the elliptical orbit and the fact that the focus (Sun) is not at the centre of the ellipse? I tried a sketch but it didn't help me.

 

[CygnusX-1]

It's just luck.

The direction the Earth's axis points varies over a period of 23,000 years due to precession. From page 88 of Ken Croswell's book Magnificent Mars: "Precession causes a planet to wobble, altering where its axis points–in particular, which hemisphere leans sunward when the planet nears the Sun." Right now the Earth is closest to the Sun in early January, but in 11,500 years that will occur in early July.

 

[Simon Peach]

Aren't our pole at different temps? Or am I missing the point of the post?

 

[stefan r]

The altitude difference is around 6 kilometers.

I remember hearing about this in an NPR interview with an areologist. The spherical cow joke is hard to forget.

 

[JMz]

Yes, I believe the altitude difference is the dominant effect.

BTW, for those who enjoy spherical cows, and especially those with a taste for astrophysical analysis (and Prof. Chandra), see a famous article on elevator operation: http://adsabs.harvard.edu/full/1972QJRAS..13...63C.

 

[sophiecentaur]

Aren't our pole at different temps? Or am I missing the point of the post?

I did sort of assume that connection in my OP.

 

[Chronos]

Since Mars has almost no atmosphere compared to earth, E3SM does not apply to mars. Temperature variance should be dominated by the integrated effects of orbital inclination, albedo and thermal emissivity of the martian surface.

 

[JMz]

E3SM = ...?

 

[sophiecentaur]

E3SM=...?

https://climatemodeling.science.energy.gov/news/acme-transitions-e3sm
Google is magic.

 

[JMz]

Quite right, of course. :-) I had imagined it was a term of art within some small (PF-only?) community.