Hmmmm! Its really very difficult to work with such a thing in PS. If you have the capability to shot RAW format or using a tripid to get 3 pictures at -2EV,0EV and +2EV, then you can try doing an HDR. The one with -2EV will give you the cloud details and the one with +2 will get you all the areas that appear underexposed here. Is this post posted after cranking up the levels? (Ctrl+L, the pushing the left slier right, and the right slider left). That would also do some help.