PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE ALBANY NY
800 AM EDT TUE JUN 24 2008

...LIGHTNING SAFETY AWARENESS WEEK CONTINUES...

THE NATIONAL WEATHER SERVICE JOINS WITH STATE EMERGENCY 
MANAGEMENT AGENCIES...THE FEDERAL EMERGENCY MANAGEMENT AGENCY 
AND THE RED CROSS IN URGING ALL RESIDENTS TO LEARN HOW TO 
PROTECT THEMSELVES FROM THE HAZARDS OF LIGHTNING. 

TODAY WE REVIEW THE SCIENCE OF LIGHTNING. 

ALTHOUGH LIGHTNING HAS BEEN SEEN IN VOLCANIC ERUPTIONS...
EXTREMELY INTENSE FOREST FIRES...SURFACE NUCLEAR DETONATIONS... 
HEAVY SNOWSTORMS...AND IN LARGE HURRICANES...IT IS MOST OFTEN 
SEEN IN THUNDERSTORMS. AT ANY GIVEN MOMENT...THERE ARE 1800 
THUNDERSTORMS IN PROGRESS SOMEWHERE ON THE EARTH. THIS AMOUNTS 
TO 16 MILLION STORMS EACH YEAR. 

A THUNDERSTORM FORMS IN AIR THAT HAS THREE COMPONENTS. 
MOISTURE...INSTABILITY AND SOMETHING SUCH AS A COLD FRONT TO 
CAUSE THE AIR TO RISE. CONTINUED RISING MOTIONS WITHIN THE STORM 
MAY BUILD THE CLOUD TO A HEIGHT OF 35000 TO 60000 FEET. 
TEMPERATURES HIGHER IN THE ATMOSPHERE ARE COLDER. ICE FORMS IN 
THE HIGHER PARTS OF THE CLOUD. 

ICE IN A CLOUD SEEMS TO BE A KEY ELEMENT IN THE DEVELOPMENT OF 
LIGHTNING. STORMS THAT FAIL TO PRODUCE QUANTITIES OF ICE MAY 
ALSO FAIL TO PRODUCE LIGHTNING. IN A STORM...THE ICE PARTICLES 
VARY IN SIZE FROM SMALL ICE CRYSTALS TO LARGER HAILSTONES...BUT 
IN THE RISING AND SINKING MOTIONS WITHIN THE STORM THERE ARE 
MANY COLLISIONS BETWEEN THE PARTICLES. THIS CAUSES A SEPARATION 
OF ELECTRICAL CHARGES. POSITIVELY CHARGED ICE CRYSTALS RISE TO 
THE TOP OF THE THUNDERSTORM...AND NEGATIVELY CHARGED ICE 
PARTICLES AND HAILSTONES DROP TO THE MIDDLE AND LOWER PARTS OF 
THE STORM.

A MOVING THUNDERSTORM GATHERS ANOTHER POOL OF POSITIVELY CHARGED 
PARTICLES ALONG THE GROUND THAT TRAVEL WITH THE STORM. AS THE 
DIFFERENCES IN CHARGES CONTINUE TO INCREASE...POSITIVELY CHARGED 
PARTICLES RISE UP TALLER OBJECTS SUCH AS TREES...HOUSES...AND 
TELEPHONE POLES. HAVE YOU EVER BEEN UNDER A STORM AND HAD YOUR 
HAIR STAND UP. YES...THE PARTICLES ALSO CAN MOVE UP YOU. THIS IS 
ONE OF NATURES WARNING SIGNS THAT SAYS YOU ARE IN THE WRONG 
PLACE...AND YOU MAY BE A LIGHTNING TARGET. 

THE NEGATIVELY CHARGED AREA IN THE STORM WILL SEND OUT A CHARGE 
TOWARD THE GROUND CALLED A STEPPED LEADER. IT IS INVISIBLE TO 
THE HUMAN EYE...AND MOVES IN STEPS IN LESS THAN A SECOND TOWARD 
THE GROUND. WHEN IT GETS CLOSE TO THE GROUND...IT IS ATTRACTED 
BY ALL THESE POSITIVELY CHARGED OBJECTS...AND A CHANNEL 
DEVELOPS. YOU SEE THE ELECTRICAL TRANSFER IN THIS CHANNEL AS 
LIGHTNING. THERE MAY BE SEVERAL RETURN STROKES OF ELECTRICITY 
WITHIN THE ESTABLISHED CHANNEL THAT YOU WILL SEE AS FLICKERING 
LIGHTNING. 

EACH SPARK OF LIGHTNING CAN REACH OVER FIVE MILES IN LENGTH... 
SOAR TO TEMPERATURES OF APPROXIMATELY 50000 DEGREES 
FAHRENHEIT...AND CONTAIN 100 MILLION ELECTRICAL VOLTS. THE RAPID 
EXPANSION OF HEATED AIR CAUSES THE THUNDER. SINCE LIGHT TRAVELS 
FASTER THAN SOUND IN THE ATMOSPHERE...THE SOUND WILL BE HEARD 
AFTER THE LIGHTNING. IF YOU SEE LIGHTNING AND HEAR THUNDER AT 
THE SAME TIME...THAT LIGHTNING IS IN YOUR NEIGHBORHOOD. 

REMEMBER...IF YOU CAN HEAR THUNDER...YOU CAN BE STRUCK BY 
LIGHTNING.

TOMMORROW WE TURN OUR ATTENTION TO OUTDOOR LIGHTNING SAFETY.  

FOR MORE INFORMATION ON LIGHTNING SAFETY AWARENESS WEEK...GO TO 
OUR WEB SITE. WWW.WEATHER.GOV AND THEN CLICK ON EASTERN NEW YORK 
OR WESTERN NEW ENGLAND. FINALLY...SELECT OUR LIGHTNING SAFETY 
AWARENESS WEEK LINK.

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OKEEFE