The pictures show exactly what my naked eye visualized.What is the cause of this?
It may not seem related, but here's a detailed answer: https://photo.stackexchange.com/questions/27643/why-dont-cameras-capture-dynamic-range-as-our-eyes-do
The camera doesn't differentiate between different colors and brightness nearly as well as our eyes do so in the photos you linked, both the clouds in-front of the sun and sky that's kind of around but looks behind the sun appear the same color and to our brains, it appears the sun is rising in the middle of the clouds - like a tall building or mountain peak might appear in the middle of some clouds.
If you were there in person when the photo was taken, this illusion probably wouldn't be there. (nice photos though).