Rope tornadoes, also known as skinny tornadoes, are narrow in diameter because they are formed from a different mechanism than wider tornadoes.
Rope tornadoes are typically the final stage of a tornado’s life cycle, as the rotating column of air narrows and becomes elongated, resembling a rope. This happens when the tornado is in the dissipating stage and is losing energy. As the air is drawn into the center of the vortex, the rotation speeds up, causing the funnel to narrow and stretch out like a rope.
In contrast, wider tornadoes, such as wedge tornadoes, are formed during the mature stage of a tornado’s life cycle, when the rotating column of air is still intensifying and growing. These tornadoes can be much wider because they have a larger and more powerful updraft, which draws in more warm, moist air from the ground.
Therefore, the width of a tornado is largely determined by the strength of the updraft, which is in turn influenced by the environmental conditions in which the tornado forms, such as wind shear and instability in the atmosphere.