nuage en étagère

OBS: Les nuages en rouleau et étagère sont des types d'Arcus.

CONT: Shelf Cloud ... is usually attached to the thunderstorm base and forms along the gust front. The leading edge of the shelf is often smooth and at times layered or terraced. It is most often seen along the leading edge of an approaching line of thunderstorms, accompanied by gusty straight winds as it passes overhead and followed by precipitation. The underside is concave upward, turbulent, boiling, or wind-torn. Tornadoes rarely occur with the shelf cloud.
OBS: Roll clouds are ... completely detached from the convective storm's cloud base, thus differentiating them from the more familiar shelf clouds.