Are you guys saying that every region of Tamriel should look like the closest approximation of the Earth-equivalent - regardless of things like atmosphere, mass, orbit, other bodies in the solar system and rotation of the planet?
Not that I'm an expert - by any means - on this, but it would seem that some of those things could be different in an alternate solar system.
If they were actually going for a "true" emulation of nature and our current perception of science.
Well, we know where Skyrim is in relation to Cyrodii. There are world maps of the Elder Scrolls universe:
http://pc-overware.be/Frenrir/Images/Jeux/The Elder Scrolls Map.jpg
Considering that the planet of the Elder Scrolls universe has extremely similar conditions to earth, and since towards the northern pole the regions get considerably colder - As proven by both Oblivion and now Skyrim - the axis of the sun should be different in those two regions.
If the axis of sun would be the same, then the temperatures in Skyrim should be the same as they are in Cyrodiil.
We can't even justify Skyrim being colder by claiming that it's much more above sea level than Cyrodiil. Because parts of Skyrim are exactly at the sea level, and I'm betting that they don't have the lush Cyrodiil nature. Moreover, Cyrodiil clearly has different environmental regions, with southern parts being warmer, and northern parts being colder. And with the exception of the very north, they are at the sea level.
We can't even justify the change between Skyrim and Cyrodiil by assuming that Oblivion happened during summer, while Skyrim happens during the winter. Because if that were the case, the days in Skyrim should be much shorter than in Oblivion. Winter happens exactly because days get shorter, and the axis of the sun is different.
These rules would apply even on another planet on another solar system. It's basic physics. Since both Cyrodiil and Skyrim would be affected by the same atmosphere, mass, orbit and rotation, I don't see how any of those things could explain the difference. Another body in the solar system, namely another sun, could affect the climate in surprising ways, but there is only one sun in the sky of the planet.
Admittedly there is at least one plausible scenario that could explain this: Maybe Skyrim and Cyrodiil would indeed otherwise have the same temperatures, but Skyrim is being hit by a cold ocean current, while Cyrodiil is being hit by warm ocean currents. The two regions are separated by a big mountain range, which might effectively stop the air current on both sides.
This would mean that the "world map" of the planet is in fact not a world map, but merely a chunk of an islands in the middle of a much grander planet that we have never seen a map of.
But ultimately my point is this: I think it's rather obvious that Bethesda are modeling the weather conditions in the ES planet to the weather conditions on earth. Cyrodiil is the equivalent of the lush Middle-Europe, with southern parts being more Mediterranean. Northern parts such as Skyrim are emulating the nature in places like Norway. All the other details follow this principle - Except for the axis of the sun.
I don't like it, because the flat top lighting tends to make everything look a little bit uglier (movies try to avoid it for a reason). And assuming that the ES universe is emulating the weather conditions on Earth (which is kinda obvious IMHO), it's simply wrong and inaccurate. They are trying to create a northern feel with the game, but they have a southern sun.
I can easily see why it wouldn't matter to other people, thought. It's just my personal pet peeve. But then again, if they could see a comparison, most people would probably agree that more emphasis on side-lighting would make the game more attractive and atmospheric. It really does make a huge difference in visuals.
…Maybe I can convince one of those modder-people to make a "Northern sun" mod once the game comes out. Shouldn't be too hard of a mod to make, I guess. Just adjusting some values for the sun.
Despite my complaints I think the game looks really good graphically. It's an open world game after all. And on my high-end PC it should look even better, even if the textures are probably identical to X-box version.