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STANDING.
I WANT TO BRING IN TOM FOREMAN.
CAN YOU TELL US UNDERSTAND HOW
THIS MONSTER MOVED ACROSS THE
REGION?
>> JAKE, REALLY THIS IS ONE OF
THE GREAT MYSTERIES OF
TORNADOES.
WHEN YOU LOOK AT THIS KIND OF
EXTRAORDINARY DAMAGE YOU WONDER
WHY DOES ONE PLACE LAST AND
ANOTHER DOES NOT?
AFTER ALL, WHEN THE STORM CAME
CUTTING THROUGH HERE IT WAS AN
EQUAL OPPORTUNITY DESTROYING
GOING ALL THE WAY THROUGH THE
NEIGHBORHOOD CUTTING A WIDE
SWATH AND HITTING MANY, MANY
DIFFERENT BUILDINGS.
SO WHY DID SOME STAND AND OTHERS
NOT?
A BIT OF IT IS CHANCE.
IT MAY BE THAT THE GUST IS OVER
200 MILES AN HOUR IN ONE PLACE
AND 50 FEET AWAY.
IT MAY ONLY BE 150 MILES AN
HOUR.
IF YOUR HOUSE GETS HIT BY THE
STRONGER ONE IT MAKES A
DIFFERENCE.
THERE IS ALSO REAL PHYSICS AT
WORK HERE AND THE PHYSICS OF
CONSTRUCTION.
THE NATIONAL OCEANIC AND
ATMOSPHERIC ADMINISTRATION HAS
LOOKED AT THE WAY WIND HITS A
BUILDING LIKE THIS, THE WAY IN A
STORM LIKE THIS IT HITS ONE SIDE
PUSHING AND CREATES A VACUUM ON
THE OTHER SIDE WHICH PULLS AWAY.
THAT CREATES LOW PRESSURE MAKING
THE PRESSURE IN THE HOUSE WANT
TO BURST OUT AND THE WHOLE TIME
AS WIND RUSHES UP OVER IT, IT
GRABS THE EAVES AND TRIES TO
OPEN IT LIKE A CAN OPENER.
THEY HAVE COME UP WITH THIS
STANDARD OF WHAT HAPPENS TO MOST
HOMES IN THAT CASE AND THIS IS
WHAT IT IS.
BASICALLY, UP TO ABOUT 97 MILES
AN HOUR, MOST HOMES CAN KEEP
THEIR ROOF ON.
ONCE THE ROOF IS TORN AWAY AT
ABOUT 132 MILES AN HOUR YOU
START SEEING WALLS FAILING AND
AT 200 MILES AN HOUR THE HOME IS
COMPLETELY WIPED OUT.
MANY PLACES WHERE THERE IS NO
HOME AT ALL BECAUSE AT SOME
MOMENT IN THAT STORM IT CRESTED
200 MILES AN HOUR IN THAT
PARTICULAR SPOT AND THAT IS WHAT
TOOK THE HOME OUT EVEN THOUGH IT
MIGHT NOT HAVE DONE IT TO A
HOUSE ONLY 50, 60 FEET AWAY
BECAUSE THE WIND MAY NOT HAVE
BEEN QUITE THAT STRONG THERE.
WHAT ABOUT SOMETHING LIKE THE
SCHOOL?
THIS IS A VERY DIFFERENT TYPE OF
STRUCTURE AS YOU CAN SEE.
IT IS FLAT AND BROAD AND THE
STANDARDS ARE DIFFERENT HERE.
IN THIS CASE, THE WINDS WILL
TAKE THE ROOF AT ABOUT 101 MILES
AN HOUR SO ONLY SLIGHTLY MORE
THAN THE HOUSE.
THE WALLS WILL GO ABOUT 139
MILES PER HOUR.
OVERALL, THE WHOLE BUILDING CAN
BE TAKEN ABOUT 176 MILES AN
HOUR.
THAT HAS TO DO WITH THE
STRUCTURE.
THINK ABOUT THIS.
THIS IS BROAD.
ALL OF THE ROOMS IN A SCHOOL BY
AND LARGE ARE BIGGER THAN THE
ROOMS IN YOUR HOME SO IF THE
ROOF AND THE WALLS START
FAILING, THERE'S LESS TO SUPPORT
IT THAN YOU WOULD HAVE IN YOUR
HOME WITH SMALLER ROOMS AND SO
IT GOES AWAY.
AND FINALLY, LET'S LOOK AT ONE
LAST CLASS HERE.
THINGS LIKE THE HOSPITAL DOWN
HERE.
WE'VE ALL LOOKED AT THIS
HOSPITAL TODAY.
IT'S HUGE, STANDING RIGHT IN THE
STORM'S PATH.
IT GETS HIT LIKE A GIANT SAIL.
YOU MIGHT THINK THIS WOULD BE
THE FIRST TO COLLAPSE BUT THE
CONSTRUCTION IN A BUILDING LIKE
THIS IS MUCH MORE ROBUST THAN
YOU MIGHT THINK.
LOOK AT THE STANDARDS HERE.
BASICALLY THIS ROOF IS GOING TO
STAY ON UP TO ABOUT 114 MILES AN
HOUR.
THE WALLS CAN STAY IN PLACE UP
TO 148 MILES AN HOUR.
EVEN IF THE ROOF AND WALLS START
FAILING HERE YOU'RE PROBABLY
JUST TALKING ABOUT THE UPPER
LAYERS OF IT HERE AND MAYBE THE
TOP FLOOR BUT NOT ALL OF THEM.
ALL OF THAT CONCRETE AND STEEL
REALLY DOES MAKE A GENUINE
DIFFERENCE SO THE WHOLE BUILDING
WILL HOLD UP ON AVERAGE TO ABOUT
210 MILES AN HOUR.
I WANT TO MAKE ONE LAST POINT,
JAKE, ABOUT THE NOTION OF
AVERAGES.
WE ARE TALKING ABOUT AVERAGES
HERE.
THERE ARE MAXIMUMS THAT HAVE
ALSO BEEN CALCULATED BY NOAA AND
THEY'RE WORTH NOTICING.
AN AVERAGE HOUSE OUT THERE CAN
STAND A MAXIMUM WIND OF ABOUT
220 AND MIGHT STILL BE STANDING.
YOU MIGHT STILL HAVE A CHANCE.
THE AVERAGE ELEMENTARY SCHOOL
OUT THERE CONSIDERABLY LOWER.
REMEMBER WHAT WE SAID ABOUT ALL
THE BIG BUILDINGS.
THEN A HOSPITAL, BIG BUILDING
LIKE THAT, PUSHING 270 MILES AN
HOUR BEFORE YOU'RE ALMOST
CERTAIN THAT IT WILL COME DOWN.
SO, JAKE, THERE IS AN ELEMENT OF