Skywatcher Chart
Pileus. The pileus is the cap of the mushroom. In meteorology, pileus clouds are formed when air at higher levels is forced to rise, either by a mountain or by a growing cumulus tower.
The air that forms pileus is drier and consequently has a much higher condensation level. This is also responsible for the smoother, horizontal shape, thus looking like a cap of the mushroom.
Image © For Spacious Skies/John A. Day
