Something else to consider when comparing Ace Combat on PS2 and this. The Wii is a particle monster so clouds, contrails, jet exhaust, etc coupled with much better wind physics will look far beyond what was seen in Ace Combat series on PS2.
I just scanned though 360 images of AC4 and saw clouds only rarely and they looked like they may have been static or above the flight ceiling. I see dynamic clouds in 2 of the 3 Sky Crawler screens.
However, I too feel they may actually be target renders. Notice the peculiarly placed sparkles on the wing tips and complex propeller blur?
The rEVOLution is not being televised