Yosemite National Park: The photos before the Horsetail shots were done in late spring. The ones after the Horsetail shots were shot in the winter. The majority of the winter shots were modified by HDR(Photomatix) by merging the highlights and shadows due to the high contrast situation in the valley.
Unfortunately, Yosemite is located in the middle of a major corridor for airlines. So, if you fly in California, odds are you have flown over Yosemite.