Q. What term has been used for the iridescent clouds, that were spotted recently over parts of Scotland, northern England, and the West Midlands?
Answer: Nacreous clouds
Notes: Recently, unusual shiny clouds called nacreous clouds were seen in the skies over parts of Scotland, northern England, and the West Midlands. These rare clouds look like mother of pearl and shine with pale, rainbow-like colors during sunset and sunrise. This effect happens as sunlight bends around tiny ice crystals in the clouds, creating colors like a thin layer of oil on water does. The process that causes these colorful iridescent clouds is optical diffraction - when light waves interact with small particles and bend or spread out into spectral colors.