This is the original image:

[![enter image description here](https://i.stack.imgur.com/3obk3.png)](https://i.stack.imgur.com/3obk3.png)

I believe I see a glow at the top, so I applied a curve to see if my suspicion was right. After applying the curve:

[![enter image description here](https://i.stack.imgur.com/GWYXZ.png)](https://i.stack.imgur.com/GWYXZ.png)

I tried playing around with brightness and the s-curve but it doesn't achieve what I want:
[![enter image description here](https://i.stack.imgur.com/zq1ST.png)](https://i.stack.imgur.com/zq1ST.png)

How can I generate a sky with **consistent** texture and brightness in photoshop?