What do tornadoes look like on the inside?
It’s a good question, but scientists really don’t know the answer. There are no visual observations from inside of a tornado since these storms create extremely violent and hazardous ground conditions.
If we placed cameras in the path of a tornado, they would either be damaged by the powerful winds and swirling debris, or they would become caked with mud and water, rendering them unable produce any useful pictures. And of course, it’s simply not safe for humans to try to observe tornadoes at close range. It’s critical to always seek shelter when tornado conditions develop.
That said, we do have some ideas about the structure of the inside of tornadoes from instruments called mobile Doppler radars. Researchers can drive these sophisticated instruments to locations near a tornado, but stop at a safe distance.
The radar directs energy toward the tornado, and when it hits the storm, part of that energy is reflected back. Scientists can analyze that reflected energy to detect important properties of the tornado. These include where there is and isn’t rain within the storm, where there is debris, how fast the winds are, and how these properties change moving away from the center of the tornado toward its outer edges and up vertically through the storm cloud above it.
Researchers use mobile radar to study tornadoes and other kinds of storms across the U.S.
We’ve learned through radar measurements that tornadoes frequently have a clear area in their centers, or at least a zone free of rain and debris. This location also experiences intensely strong vertical winds, which are sometimes powerful enough to suck pavement up from roads.
This clear space is encircled by a ring of heavy rain and debris that is typically moving outward, away from the tornado’s center. That’s because the winds are spinning incredibly fast and creating centrifugal force that pulls these objects away from the center of the storm. Areas of heavy rain that are a bit farther out from the tornado sometimes spiral inward toward the area of rotation, like the spiral bands that extend outward from the eye of a hurricane.
Some tornadoes feature a single main funnel cloud. Others have multiple small funnels that rotate around each other. It may come as a surprise that there are even tornadoes that don’t have a funnel cloud at all. That’s because as long as winds are rotating in a tight circle all the way from the storm cloud down to the ground, it’s a tornado, even if atmospheric conditions haven’t condensed water vapor in the air into a visible funnel.
Scientists have also learned that many tornadoes don’t actually descend from the cloud to the ground. Rather, they form at the ground and quickly build upward – often in less than a minute.
Tornadoes can form at the ground before radar detects rotating winds at low levels.
When that happens, your eyes may fool you if you’re watching for a funnel cloud coming down from the sky. There could already be tornado-strength winds at the surface, even without that funnel cloud. So be careful – when it comes to tornadoes, looks can be deceiving.
Written by Jana Houser, Associate Professor of Geography, Ohio University.
This article was first published in The Conversation.