Well today is overcast so visibility is not as good as it normally is. I live in the higher desert area about 30 miles north of Phoenix proper so there are quite a few "mountains" or what most people call hills around me. Standing in that flat area in the pic above, I can clearly see the mountain range that surrounds north Scottsdale which is about 10 miles from me on an overcast day like this no problem.
Ten miles!!! I am lucky to see one with all the forest around here.