Step 6. Open image in Photoshop and also the top frame with a properly exposed sky. drag this sky onto a new layer on top of the vertorama and roughly align the horizon.
Step 7. Create a layer mask on the top sky layer by selecting the sky layer first and then click on the white square with a hole in at the bottom of the layers pallete to create the mask. This shows as the white rectangle next to the sky image at the top of the layers pallete.
Step 8. Enlarge the image first where the join will be. Now i have selected a soft brush which i will paint over the bottom part of the sky image to mask off everything below the horizon.
Step 9. Select the brush tool and with a smaller size selected increase hardness to go over the horizon above the mountains to get a neat merge, reducing opacity also helps with the merge.
Step 10. Adding a new levels adjustment layer to darken down the top 2/3 rds of the image, masking off the bottom trees which look ok.