thank you, guys.
#2 is special in that regard that the sun was too low to shine on the dark bushes on the ground, yet it was still at the right angle to illuminate the yellow / orange trees which stood out. a matter of a few minutes, then it was gone.
#3: yes, a polarizer helped to refine the details of the sky. the same mountains in the background as in #4, btw.
eventually the pictures are too saturated, i think.