This simulation was created by NCAR scientist George Bryan to visualize what goes on inside a tornado. The animation is the "high swirl" version in a series that goes from low, to medium, to high. (Courtesy George Bryan, NCAR. This image is freely available for media & nonprofit use.)

What's really going on inside a tornado? How fast are the strongest winds, and what are the chances that any given location will experience them when a tornado passes by?

Due to the difficulties of measuring wind speeds in tornadoes, scientists don't have answers to these questions. However, a collaborative project between researchers at the University of Miami and NCAR has been seeking clues with new, highly detailed computer simulations of tornado wind fields.

The simulations can be viewed in a series of animations, created by NCAR scientist George Bryan, that provide a 3D window into the evolving wind fields of idealized tornadoes at different rates of rotation.

The "high-swirl animation," shown here, which depicts a powerful tornado with 200-plus mph winds, the purple tubelike structures depict the movements of rapidly rotating vortices. Near-surface winds are represented by colors ranging from light blue (less than 20 meters per second, or 45 mph) to deep red (more than 100 meters per second, or 224 miles per hour). The vortices and winds are contained within a condensation cloud that rises more than 500 meters (1,640 feet) above the surface.

Such visualizations can help atmospheric scientists better understand the structures of tornadoes, as well as the shifting location and strength of maximum wind speeds.  Bryan also uses them in presentations to meteorology students.

“When you make these 3D visualizations and then animate them, they give you a sense of how the flow evolves and how the turbulence changes,” Bryan said. “These are details you don’t see by just looking at a photograph.”

For example, he learned from the visualization that the rotating tubes tilt backward against the flow at higher altitudes. These are the kinds of details that can eventually help scientists better understand these complex storms.

The information is also critical for public safety officials and engineers.

“If you’re an engineer and designing a building, you want to know details like how much greater is peak wind over average wind in a tornado,” Bryan said. “We’ll get questions from engineers asking about the details of wind gusts in those purple tubes.”

Bryan is collaborating on the simulations with Dave Nolan, chair of Miami’s Department of Atmospheric Sciences.

To create the animation, Bryan used innovative NCAR software that enables researchers in the atmospheric and related sciences to analyze and interpret results from large computer models. VAPOR (Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers) is an interactive 3D visualization environment for both animations and still-frame images. The open-source software can be downloaded and used on personal computers.

VAPOR was developed at NCAR in partnership with the University of California at Davis and Ohio State University. Funding comes from the National Science Foundation and the Korea Institute of Science and Technology Information.

Funder

National Science Foundation

Collaborator

University of Miami

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