Tornado Detection:
(SFX: tornado. . . clearly. . .fading into a hum)
     THE NOISE OF A TORNADO CAN BE ALMOST DEAFENING, BUT HIDDEN DEEP INSIDE
IS A MUCH MORE SUBTLE SOUND.  THE WHIRLING VORTEX AT THE CENTER OF A TORNADO
MAKES  A HUM MUCH TOO LOW FOR A HUMAN TO HEAR.  

     Bedard: "there is a lot that is going on in the atmosphere and it is completely
subaudibleto us which is fortunate in a way because we would end up listening to our
circulation and bodily sounds and all kinds of noises in the atmosphere which would be
very confusing."

     BUT AL BEDARD IS LISTENING FOR JUST THOSE SUBAUDIBLE TORNADO HUMS.  HE'S A
PHYSICIST AT THE UNIVERSITY OF COLORADO AND HE'S DISCOVERED THAT HE CAN TUNE
INTO THOSE UNHEARABLE NOISES WITH MICROPHONES.  THAT MEANS HE MIGHT BE ABLE
TO GIVE COMMUNITIES ADVANCE WARNINGS ABOUT AN ONCOMING TORNADO.

     Bedard: "The nice thing is this is a passive system so we're not actually chasing
tornadoes. . . what we do is passively wait and listen." 

     HIS SYSTEM USES FOUR SENSORS TO LISTEN FOR THE HUMS DEEP INSIDE THE
WHIRLING TORNADO AND THEN TRIANGULATES THE  LOCATION OF the HUM.  THE SYSTEM
CAN DETED TORNADOES UP TO SEVERAL HOURS AWAY.  BEDARD SAYS THAT THE SOUND
OF THE HUM CHANGES WITH FROM TORNADO TO TORNADO.  BIGGER CYCLONES HAVE
LOWER SOUNDS.  HE THINKS THAT BY MEASURING THE PITCH OF the HUMS, HE SHOULD
ALSO BE ABLE TO GIVE COMMUNITIES ADVANCE WARNING ABOUT THE SIZE OF AN
ONCOMING TORNADO.  BEDARD HOPES TO GET A TEST SYSTEM UP AND RUNNING
OKLAHOMA THIS SUMMER.