Here is an example of how to adjust the sky/ground transition in an image with very strong light pollution on the horizon:
1. Result with default adjustments
As there is a lot of light pollution on the horizon, the default sky/ground blending does not quite manage to solve this particular situation, so the sky/ground transition does not look natural at all. As always, the first thing to do is to check that the general adjustments of the sky/ground transition are selected (red arrow).
Applying a geometric transformation to the sky image is a very effective way to solve the problem of intense light pollution on the horizon. Thus, by applying a small stretch (both vertically and horizontally) to the sky image and, in addition, shifting the sky all the way down (+100), most of the light pollution is below the horizon and, therefore, no longer affects the sky/ground blending.
3. Adjusting the sky transition
The radius of the sky transition is increased to definitively solve the problem of intense light pollution on the horizon. Thus, the transition zone of the sky is wider and the light discontinuities caused by all the light pollution concentrated in the horizon zone are better covered.
4. Adjusting the exposure balance
It was decided to decrease the exposure balance a little (by half a stop) to equalize the light intensity of the horizon area with the rest of the sky.
5. Adjusting the ground transition