美国西弗吉尼亚州上空的火彩虹
2021年8月30日 A Fire Rainbow over West Virginia Image Credit: Christa Harbig Explanation: What’s happening to this cloud? Ice crystals in a distant cirrus cloud are acting like little floating prisms. Known informally as a fire rainbow for its flame-like appearance, a circumhorizon arc appears parallel to the horizon. For a circumhorizontal arc to be visi...