What is a storm cloud called?
a storm cloud is called a cumulonimbus.
Cumulonimbus incus, which has an obvious anvil top. Only very strong ones, called supercells, spawn tornadoes. Cumulonimbus icnus is the most likely type of storm cloud to produce a tornado. These cumulonimbus clouds are often supercells. Tornadoes can form from any cumulonimbus cloud, but they usually form from Cumulonimbus incus (heaped rain cloud with anvil) with a rotating updraft called a mesocyclone. The type of storm this rotating cumulonimbus cloud brings is a strong thunderstorm…
It's not so much the anatomy of the cloud itself, but that of the wind currents in and around it. First, the updraft of the storm must rotate, this rotation often producess a lowering of the cloud base called a wall cloud. Second, a downdraft must descend from the back of the storm, often producing a hole in the clouds. This downdraft allows the rotating updraft to produce a tornado.