The image was very well composed but sky was dull and plain.
Using Photofilre added contrast to the image which completely whited the sky. Thereafter using Magic wand tool copied the shape of the white sky and pasted in second image of sky. The shape from the first image allowed to crop the exact sky which fitted well into the original image.
I tried same thing yesterday with another image however in that WS some grainy patches remained.
But the present image was crisp so it worked smoothly.