I l everything about thish shot but the tree. The colors and the play of light on the clouds and the grass are first rate, but the tree is so small in the frame that its form needs to be iconic, very tree like, with a trunk holding the crown into the sky. The tree here, could be a shrub since all we see is a blob of green, and it makes the scale uncertain. It may be a personal prefrence, but for me it knocks this fine shot out of ribbon teritory.
The sky is great and I like the composition. It looks like this has been processed carefully. I wonder what would have happened if you'd walked forward somewhat... I wish the trunk of the tree were visible!
Lovely sky and interestingly devoid terrain. The tree is barely discernable as a tree - without a scale reference, it might as well be a bush. Overall, a nice photo in search of a little more subject.