From a bug downstream at https://bugs.launchpad.net/weather-wallpaper/+bug/138026 I found the source of the images to be from the Tango project. The problem is with the weather-few-clouds icon, where a large sun with a cloud in front and a cloud behind the sun is shown. There should only be clouds between the observer and the sun. Same goes for the moon in weather-few-clouds-night.
Just like cartoon characters have only 4 fingers, no harm is done here by having the sun obstruct a cloud. Iconic representation doesn't aim to be realistic.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.