Final answer:
Supercell thunderstorms acquire rotation due to the environmental condition known as wind shear. Wind shear is the change in wind speed and direction with height. This rotation is necessary for the formation of tornadoes, which are often associated with supercell thunderstorms.
Step-by-step explanation:
Supercell thunderstorms acquire rotation when there is a specific environmental condition known as wind shear. Wind shear occurs when the speed and direction of the wind changes with height. In the case of supercell thunderstorms, the difference in wind speeds and directions creates a rotating column of air. This rotation is essential for the development of tornadoes, which are often spawned by supercell thunderstorms.