Scientists Get Closest Look Yet at Tornado
Riding along the VORTEX2 storm expedition
"I think we're about to have ourselves a tornado," Glen Romine calmly stated - in the same tone of voice as one might order food at a restaurant -- as he gazed at a low and rotating mass of clouds, known as a wall cloud, in Goshen County, Wyoming on June 5. His calmness was in stark contrast to the broiling sky, as a funnel cloud descended towards the ground before lifting back up again just to the south of our vehicle along a narrow country road.
"Yup," I replied, my gaze locked onto a patch of bare ground right underneath the incipient tornado, awaiting touchdown. Suddenly, the lightly colored funnel touched the ground, and the world's most well-observed tornado was born.
Keep reading to continue on this storm-chasing journey...
This tornado, which occurred far from any heavily populated community, was surrounded by an armada of cutting edge scientific instruments - from mobile radar units to tornado "Pods" - which together are designed to scan a developing tornado from all angles and collect ultra high resolution data on its entire life cycle. These assets are being brought to bear as part of the VORTEX2 tornado experiment, a $10.5 million dollar project that is the largest tornado field experiment in history.
As the tornado spun its way to the east, I expected some jumping up and down and shouting like one sees in documentaries and reality shows like the Discovery Channel's "Storm Chasers." But Romine, a research scientist in meteorology at the University of Illinois at Urbana-Champaign, and graduate student Isaac Hankes were focused on their scientific mission, which left no time for indulging in tornado-related revelry despite the fact that the VORTEX2 team had waited since May 10 to see their first tornado.
Romine and Hankes were scouting locations to place two specialized instrument probes, called disdrometers, to take measurements of precipitation falling underneath the main updraft region of the supercell thunderstorm. The updraft region is the area where the thunderstorm breathes in air and launches it to great heights. 'Supercell' thunderstorms like the one in Goshen County have a persistent rotating updraft, and Romine said that scientists are becoming more aware of how precipitation processes and the related composition of the air mass underneath the updraft area can help determine whether a supercell produces a tornado.
Why some supercells are tornadic and others are not is one of the key mysteries that VORTEX2 researchers are trying to unlock.
Romine and Hankes pulled their modified Dodge Caravan into a small driveway. Ever so calmly despite the looming tornado, they got out of the van and lifted the disdrometer from the back seat. The data probe containing the disdrometer resembles a modern art sculpture that one might see at MOMA in New York, with a heavy metal base for an anchor, and several protrusions, including a black V shape near the top. To help ensure that it wouldn't blow over in high winds, the researchers placed the probe on level ground.
To measure precipitation characteristics such as how big the water droplets are and how fast they are falling, the disdrometers Romine and Hankes deployed utilize a small laser beam. Any precipitation that falls through the beam can be measured based on how it distorts the beam's voltage path.
Precipitation such as rain and hail offers clues, Romine said, about the air mass in the updraft region, since different droplet sizes have different surface areas. Small droplets may be more effective at cooling the air underneath an updraft, which could inhibit tornado formation.
Once their two probes were placed, Romine and Hankes began driving transects between them to gather data from the weather equipment mounted on top of the van. This data will be used to fill in the gaps regarding the weather conditions between the two probes.
As most other tornado chasers were hightailing it out of the area ahead of the storm's "rear flank downdraft," which is a blast of cool air, rain and hail that wraps around the backside of a tornado, the disdrometer team, with me in the back seat, headed in. Large hail began splattering on the windshield and bouncing off the pavement. Soon it was a deafening assault of golfball-sized hail and high winds, denting the car but sparing the windshield. Romine and Hankes hoped that their probes held up against the onslaught.
Upon retrieving the probes, Romine and Hankes discovered that a large and strategically placed hailstone had hit the power switch of probe one, knocking it out of commission after recording about six minutes of data. They shrugged it off as a lesson learned. "This is the joy of trying this stuff for the first time," Romine said, as he quickly modified the power switch to be more resistant to such hail damage in the future.
"Except for the switch, that was pretty much a perfect deployment for us," Romine said, summarizing the entire VORTEX2 team's experience for the day.
Romine, Hankes and others will work in the coming years to analyze the data they gathered in Goshen County and elsewhere, with the ultimate goal of translating their findings into improved tornado warning techniques that could save lives.
"Hopefully knowing more about what's going on internally with the microphysical structure of the storm will lead to better warnings," Romine said, noting that the next generation of radars that will replace the country's current network will have additional capabilities to detect precipitation characteristics in thunderstorms.
Follow Andrew Freedman (the author) on Twitter as he continues to ride along with the VORTEX2 team: http://www.twitter.com/capitalweather. Also, join CWG's Facebook group to see more photos from this expedition.
| June 8, 2009; 10:00 AM ET
Categories: Freedman, Thunderstorms, VORTEX2
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