{"copyright":"Christa Harbig","date":"2026-08-02","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 visible, the Sun must be at least 58 degrees high in a sky where cirrus clouds present below --  in this case cirrus fibratus.  The numerous, flat, hexagonal ice-crystals that compose the cirrus cloud must be aligned horizontally to properly refract sunlight in a collectively similar manner.  Therefore, circumhorizontal arcs are somewhat unusual to see.  The featured fire rainbow was photographed in 2021 near North Fork Mountain in West Virginia, USA.    Sky Surprise: What picture did APOD feature on your birthday? (after 1995)","hdurl":"https://apod.nasa.gov/apod/image/2608/FireRainbow_Harbig_4000.jpg","media_type":"image","service_version":"v1","title":"A Fire Rainbow over West Virginia","url":"https://apod.nasa.gov/apod/image/2608/FireRainbow_Harbig_960.jpg"}