English: Thermal image of 22 degree solar halo above Missoula, MT, USA on 2013-05-15. Part of the sun itself can be seen at the top center of the image. The halo itself is not visible in the thermal infrared spectrum, as the ice crystals responsible for the optical effect are opaque to thermal wavelengths. However, the ring of cold temperatures responsible for the ice crystals can be seen. (note: this is a FLIR format "radiometric JPEG" and the 16-bit RAW thermal data can be viewed with appropriate software)