アメリカ内務省さんのインスタグラム写真 - (アメリカ内務省Instagram)「Snow is possible any time of year in Yellowstone National Park, but during the winter months, the park transforms into a wonderland of winter phenomena. One of which is the sun dog, or parhelion. They are a member of the family of halos caused by the refraction of sunlight by ice crystals in the atmosphere. Sundogs are most common when temperatures are extremely cold and the sun is low on the horizon. If you plan to visit #Yellowstone in #Idaho, #Wyoming or #Montana this winter, plan ahead and prepare. Many of the features including Old Faithful and the Grand Canyon of the #Yellowstone (pictured here) are only accessible by guided #snowmobile or #snowcoach #tours. Photo @yellowstonenps by Jacob W. Frank, National Park Service. #usinterior #yellowstonenationalpark #yellowstoneNPS」11月19日 2時33分