Click thumbnails for a larger image: -
 |
Pileus (pil) – pileus meaning ‘cap’, this flattened cloud often appears above a cumulus congestus or cumulonimbus calvus cloud. Upward convection results in a layer of icy fog. Unlike the incus or ‘anvil’ above a cumulonimbus capillatus, these clouds are short-lived and swallowed up by the cloud below. |
 |
Pannus (pan) – pannus meaning ‘cloth’ or ‘rag’, these ragged stratus fractus or cumulus fractus clouds appear beneath other, often rain bearing, clouds. Also known as scud or messenger clouds, they often accompany or precede rain. |
 |
Velum (vel) – velum meaning ‘sail’ or ‘awning’, these clouds form a thin, long-lived ’veil’ through which cumulus congestus or cumulonimbus clouds rise. |