How do tornadoes form?

Scientists don’t fully understand exactly how tornadoes form, but the phenomenon has been heavily observed. When warm rising air (updraft) meets cooler sinking air (downdraft), and there is a change in wind direction and speed, a horizontal spinning effect can happen in a cumulonimbus cloud. If more updraft tilts the spinning air current from horizontal to vertical, a condensation funnel cloud (funnel-shaped cloud made of water droplets) may form. If that funnel cloud touches the ground or gets close enough to the ground to pick up debris or cause damage on the ground, the funnel cloud is called a tornado. Tornadoes are visible because of the water droplets in the cloud and because of the dust and debris the tornado accumulates in its path.