Want to see Yosemite’s famed ‘firefall’? A reservation is now require…

For a rare, if not lucky, few days a year, Yosemite National Park’s famed El Capitan granite cliff converts into what looks like an active volcano jutting 3,000 feet above the valley floor.

The conditions need to be right, including early-evening clear skies, generally in February, and plenty of water. Should the sunset properly backlight a small waterfall known as Horsetail Fall just so,…