STORM TRACK: September 30, 1979 (Volume 2 Issue 6)
Although I have seen and photographed over 60 tornadoes and funnels, I've only heard the distinctive roar once, and there was no visible tornado at that time. Of the other storms, I've been within -- mile of one funnel and within l-2 miles of three tornadoes, one funnel and a small, rotating CB base. Two of the three tornadoes were at least F3 based on recorded damage or diameter of vortex-ground contact. On each occasion, I observed them from outside of a car or from inside -with an open window- but heard no roar or otherwise unusual sound. On all but one of these six "close encounters," I was in little or no rain. From these few experiences, it appears that if the roar can be heard the listener is very close -perhaps within 3/4 of a mile.
The one time that I did hear the roar was on May 22, 1968. A NE-SW front. lay from central Kansas to NW Oklahoma and then to NE New Mexico. The frontal demarcation was sharply defined by sensibly cooler air and a 180 deg windshift from NE to SW, just east of the front. My surface map for 1300 CDT that day shows a well organized 971 mb low in NE New Mexico that dominated the pressure pattern and winds to Shreveport, La. and to Des Moines, IA. I drove ENE from Gage, OK to Hazelton, KS, then E to Caldwell and back to 12-14 miles west of Caldwell. En route I watched the initial buildups -some small and extremely turbulent near Hopeton, OK. I saw the first sustained cell build to a small anvil at 1717 CDT NE of Bryon, 0K.
It was only minutes afterward that I phoned the Wichita Weather Bureau radar operator to inquire as to size and movement of this cell. He reported nothing on radar, and I learned an early lesson -that radar (at least in 1968) didn't detect early stage, potentially severe CBs, which were otherwise evident to the experienced observer.
At 1900 CDT, I photographed the second cell to build and sustain itself -from 8 miles S of Hazelton, KS.
It was this cell that very likely produced the isolated but very strong cell below, which contained a well organized counter-clockwise rotating hole. After driving to Caldwell and overcoming the problem of cold lens condensation shown in Funnel Funnies, I charged to a location 12-14 miles W of Caldwell. At 2010 CDT, I photographed this base until it gradually broke up about 15 minutes later I was looking W at this rotation and heard a distinct, loud and continuous roar (as hundreds of jet planes high overhead). My recollection is that Wichita radar recorded a cloud top briefly to 67,000 feet (if not this, it was at least 57,000 feet) and higher than anything else in the area. The roar continued steadily and faded slowly as the cell began to break up.
At this point I noted something quite interesting. Although initially assuming the source of the sound to be from this rotation, I slowly turned my head from side to side to try to confirm it. I was surprised to discover that it seemed to become omnidirectional! Though I tried to localize the source, fully turning my head 180 deg and overhead, the apparently obvious source could not be confirmed. I can only conjecture that the overcast produced an echo chamber effect, making source determination difficulty I will return to this in the next paragraph, with some comments on needed studies on tornado sounds. The earliest reported tornadoes were 7 and 18 minutes later (2017 and 2028 CDT) and 25 miles NE of this location -near Wellington, KS. At the time of the initial occurence, the roar W of Caldwell had almost entirely ceased. At no time did I observe either a vortex cloud or any dust or debris on the ground beneath the rotating hole -despite excellent visibility, with low backlighting under the cell. The rotating hole in middle of,base was illuminated, apparently by,higher opening in cloud. Regarding the source of this sound, the adjacent diagram suggests a possible explanation.
Note that a low (10-15,000 feet) and dense anvil was overhead, extending eastward from the rotating hole- cell, and merged with heavy CB bases with moderate to heavy rain from NE-SE. Light to moderate rain fell from NNW-NE. The CB base,easterly, was about 10-l5 miles distant, Consequently, I was in a generally clear pocket with clouds or precip from W-N-E. Wichita radar did confirm a hook echo in this formation at the time of my observence. If the sound were near to the ground -in the rotating hole, I would expect greater attenuation of the echo reflected from behind ms. However, since the intensity of the sound was identical from all sides, I would conclude that the source came from much higher up (perhaps 20-30,000 feet). This should be expected -- the closer the primary sound track is to its reflected track. I am obviously no acoustics expert and appreciate that many other factors may explain such a phenomenon. However, this seemed most plausible to me. What do you think? Write Storm Track and let me know!
Such occasions -- and subsequent conversations with Dr. John Stanford of Iowa State University -- have suggested to me that much more research needs to be done on the acoustical properties of tornado sounds and what they tell us about, the dynamics of the storm. Some questions which occur to a layman such as myself:
(1) Is the sound primarily a result of wind shear or is it, also produced by hail entrainment and collision around the vortex, continuous lightning or ground debris?
(2) Does the "sound generator" begin high in the tornadic cell and then descend as the vortex takes shape?
(3) Does it sound differently at the same time from different, locations?
(4) What does the absence of sound signify; when and why? Dr. Stanford reported that some farm families immediately next to the huge Ames, Iowa tornado of June 13, 1976 reported no tornado roar,
(5) Is the sound loudest at the tornado's onset in the cloud or on the ground?
(6) What is the significance in changes of pitch, tone, etc ? It would appear that inconsistencies in the experience of witnesses to tornadic sounds warrants a lot more research in the area than this layman is currently aware of. If you have had interesting sound experiences, by all means write to Dr. John Stanford, Physics Department, Iowa State University, Ames, Iowa 50011. Also, let ST readers know.
