Definition of cirrostratus in US English:



  • Cloud forming a thin, more or less uniform, semitranslucent layer at high altitude, usually 16,500–45,000 feet (5–13 km).

    • ‘Halos form when light from the sun or moon is refracted by ice crystals associated with thin, high-level clouds (like cirrostratus clouds).’
    • ‘The cloud most suited to halo formation is cirrostratus, which is most commonly observed well ahead of a developing frontal system.’
    • ‘Stratosphere air contains little water vapor or dust; only wispy cirrostratus clouds streak the distant sky.’