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Tornadoes are among the most violent storms on Earth, with the potential to cause very serious damage. Although no two tornadoes are the same, they need certain conditions to form -...
explore where tornadoes exist in the world, how they form, and how to stay safe if a tornado is close to you. Introduction to Tornadoes (5:01) Figure 1 divides tornado strength into three categories: weak, strong, and violent. The average tornado is weak and produces wind speeds that are generally less than 120 mph. While 85% of all
The primary tornado vortex had a core diameter (dis-tance from peak inbound to peak outbound Doppler wind speeds) from approximately 500 m at 250 m AGL to 700 m at 1000 m AGL. So, multiple vortices re-volving around the tornado at 0.5–1.0 times the peak tornadic wind speed (see propagation speed discussion
These tornadoes form from a vertically spinning parcel of air already occurring near the ground caused by wind shear from a warm, cold, or sea breeze front, or a dryline. When an updraft moves over the spinning, and stretches it, a tornado can form.
Typical supercell pattern: Upper trough/low to NW with jet exit region (even right exit region) over area. LLJ increases in response pulling axis of instability and strong shear northward. Storms often form in gradient zone of instability.
How Tornadoes Form. A tornado can form in a thunderstorm where the rotating air of an updraft (shown in purple) meets the rotating air of a downdraft (shown in aqua), which has turned upward. Tornadoes only form when a thunderstorm has a particular combination of winds.
Tornadogenesis. Tornadogenesis: the formation of tornadoes, whose detail processes are not clear due to limited observations. Tornadogenesis appears to occur in one of three ways: (1) top down process (a dynamic pipe effect), (2) bottom up process, and (3) vortex breakdown.
