A cumulonimbus cloud
All tornadoes are produced by thunderstorms.
Tornadoes are a product of severe thunderstorms, which take the form of cumulonimbus clouds.
Low pressure system
rain clouds
nimbus clouds
Most tornadoes are produced by rotating thunderstorms called supercells.
cumulonimbus
Most tornadoes are produced by thunderstorms called supercells. Tornadoes spawned by other types of thunderstorm are generally weaker.
Tornadoes, especially strong tornadoes, are most often associated with a type of thunderstorm called a supercell.
Tornadoes are associate with cumulonimbus clouds, wall clouds, and funnel clouds. Hurricanes are associated with cumulonimbus clouds and cirrus clouds.
A cold front.
Tornadoes are associated with a type of thunderstorm called a supercell.