22º radius halos are visible all over the world and throughout the year. Look out for them whenever the sky is wisped or hazed with thin cirrus clouds. These clouds are cold and contain ice crystals in even the hottest climes.
What happens is that millions of ice crystals glint down, from the 3 to 5 mile high cirrostratus haze, to form the 22º halo. The sharp inner edge is red tinged. Beyond that the halo fades gradually away. The sky Inside is dark because no crystals can glint there.
Photographed in "The Wave" of Coyote Buttes, in the Vermilion Cliffs / Paria Canyon Wilderness of Northern Arizona.