Pannus or scud clouds are a type of fractus clouds, found on thunderstorms. They appear as ragged cloud shreds at low altitude above the ground and detached from beneath the thunderstorm base.
- Ragged and wispy in appearance.
- Often along the gust front on a thunderstorm.
- They form by forced lift along the gust front and mixing (entrainment) of cooled outflow air.
- May also form in the inflow region of the storm by mixing (entrainment) of cooled outflow air. Pannus (scud) clouds in this region may form a wall cloud and/or inflow tail.