Elevation explains why bridges freeze before roads

Elizabeth Gardner demonstrates how cold air above and below makes bridge surfaces freeze more quickly than surface roads.
Posted 2/21/2020, 10:59:00 AM Updated 1/21/2022, 3:35:40 PM

WITH SOME HEAVY SNOW SO WE MAY

CONTINUE TO SEE MORE POWER

OUTAGES AS WELL.

THE SLICK ROADS AND THE BRIDGES

THAT BRIAN WAS TALKING ABOUT.

AND IT MAY SEEM OBVIOUS BUT

SOMETIMES IT'S NICE TO JUST

SORT GO OVER THE FACT THAT

HERE'S WHY BRIDGES GET COLDER

AND THEY GET SLICKER THAN THE

MAIN ROAD DOES.

SO YOU HAVE AIR OBVIOUSLY THAT

GOES UNDERNEATH THE BRIDGES.

SO THE AIR TEMPERATURE WILL BE

DROPPING AND OF COURSE WE'LL

CONTINUE TO SEE OUR AIR

TEMPERATURE DROPPING AS WE HEAD

THROUGH THE MORNING.

ON DOWN TO 25 OR 26.

SO THAT'S WHAT'S UNDERNEATH THE

BRIDGE.

NOW THE ROAD TEMPERATURE MAY BE

40 DEGREES WHERE IT'S SITTING

OVER THE GROUND.

OUR GROUND TEMPERATURES ARE 40,

45 DEGREES.

BUT THE BRIDGE TEMPERATURE

CONTINUES TO DROP AS THAT COLD

AIR CIRCULATES UNDER IT.

AND OF COURSE THAT'S WHERE WE

GET THE ICE.

SO IT MAY SEEM LIKE EVERYTHING

IS JUST FINE.

YOU HIT THAT SLICK BRIDGE AND

EVERYTHING BEGINS TO SPIN.

SO WE'RE GOING TO SEE THAT

THROUGH THE MORNING UNTIL WE

© WRAL