If cameras were placed in the path of a tornado, they would either be damaged by strong winds and swirling debris, or congeal with mud and water, preventing them from producing any useful photos, said Jana Houser, an associate professor of geography at Ohio University. Of course, it is not safe for humans to try to observe a tornado up close. When tornado conditions arise, the key is to always seek shelter.
That being said, the researchers do have some ideas about the internal structure of the tornado, and these instruments are called moving Doppler radars. Researchers can drive these sophisticated instruments to a site near a tornado, but stop at a safe distance.
The radar directs the energy towards the tornado, and when it hits the storm, some of the energy is reflected back. Scientists can analyze these reflected energy to detect important properties of tornadoes. These include where there is rain in the storm, where there is no rain, where there is debris, how fast the wind is, and how these properties change from the center of the tornado to its outer edge and vertically through the storm clouds above it.
The researchers learned from radar measurements that tornadoes often have a clear area in their center, or at least an area free of rain and debris. The place also experienced strong vertical winds. This clear space is surrounded by a ring of heavy rain and debris that usually travels outward, away from the center of the tornado. This is because the wind spins very fast and creates centrifugal force that pulls these objects away from the center of the storm. Areas of heavy rain just a little further away from the tornado can sometimes spiral toward the swirling zone, like a helix extending outward from the eye of a hurricane.
Some tornadoes have a single main funnel cloud. Other tornadoes have multiple small funnels that spin around each other. Perhaps surprisingly, even some tornadoes have no funnel clouds at all. That’s because as long as the wind rotates in a tight circle from the storm cloud all the way to the ground, it’s a tornado, even if atmospheric conditions don’t condense water vapor in the air into a visible funnel.
Scientists also learned that many tornadoes don’t actually descend from the clouds to the ground. Instead, they form on the ground and develop rapidly upwards — often in less than a minute.
Tornadoes can form on the ground before radar detects low-altitude swirling winds.
When that happens, your eyes may be deceiving you if you’re looking at a funnel cloud coming down from the sky, the researchers said. Even without the funnel cloud, the ground may already have tornado-strength winds. So be careful – appearances can be deceiving when it comes to tornadoes.