iOS 7 clouds don't move on weather app
There are many graphical upgrades in iOS 7 that simply don't work on iPhone 4 because of the relative lack of processing/GPU power. See this Ars Technica article for a list of the features disabled on iPhone 4.


  What don't you get?
  
  The slowest devices in Apple's lineup tend not to get every single feature that the newer ones get. Generally, this is either because the old hardware is incapable of supporting it or because the device's aging system-on-a-chip (SoC) isn't fast enough to provide a good experience. The iPhone 4 gets most of the features we highlighted in our massive iOS 7 review, but there's a long list of fine print attached. Let's run through not just the list of iOS 7 features it misses out on, but also the features from previous iOS versions that it isn't privy to. If the feature is on this list, it's missing from the iPhone 4.
  
  
  3D Flyover or turn-by-turn navigation in Maps.
  Panorama mode or Filters in the Camera app (filters can still be applied after-the- fact in the Photos app).
  AirPlay Mirroring.
  Siri.
  AirDrop.
  A number of the new graphical effects present on all other iOS 7 devices. These include translucency effects throughout the OS, live wallpapers, and the parallax effect used on the Home screen.