1. "Lenticular clouds over Mount Fuji, Japan."
Sorry — it's photoshopped.
2. "Rainbow meets Tornado"
Also photoshopped, sad to say.
3. "Solar Eclipse and Milky Way seen from ISS"
That's actually a computer-generated artwork made by deviantART member A4size-ska.
4. "Spectacular View of The Stars in Alaska"
This one seems to originate from an art forum, under the category "Fantasy/Landscape."
5. "Difference between day and night!"
No single spacecraft or astronaut took this picture. It is a digital composite of archived images taken by several Earth-orbiting satellites and ocean-faring ships... This image is different from what an astronaut would see for reasons including a complete lack of clouds and an unrealistic exaggeration of lights and contrasts. The image has become both an internet wave in that it continues to circulate as an attachment to digital correspondence, and a modern urban legend.