Quiz: Remember the definition of mal de mer?
Plural cirrostrati (sîr'ō-strāt'ī')
A thin, hazy, high-altitude cloud composed of ice crystals, often covering the sky in sheets and producing a halo effect around the sun. Cirrostratus clouds generally form between 6,100 and 12,200 m (20,000 and 40,000 ft). See illustration at cloud.