An accessory cloud of small horizontal extent, in the form of a cap or hood above the top or attached to the upper part of a cumuliform cloud that often penetrates it. Several pileus may fairly often be observed in superposition.
Occurs principally with Cumulus and Cumulonimbus.
The text enclosed in grey-shaded boxes, like this example, comprises Annex I to the Technical Regulations (WMO-No. 49) and has the legal status of standard practices and procedures.