NZUS01 KLZK DDHHMM
WRKPNS
ARZ003>007-012>016-021>025-030>034-037>047-052>057-062>069-241900-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE LITTLE ROCK AR
600 AM CDT MON JUN 24 2013

...GENERAL OVERVIEW OF LIGHTNING...

THIS IS NATIONAL LIGHTNING SAFETY AWARENESS WEEK.

THE NATIONAL WEATHER SERVICE...THE ARKANSAS DEPARTMENT OF EMERGENCY 
MANAGEMENT...THE ARKANSAS DEPARTMENT OF PARKS AND TOURISM...THE U.S. 
ARMY CORPS OF ENGINEERS...THE ELECTRIC COOPERATIVES OF ARKANSAS...
AND ENTERGY ARKANSAS INCORPORATED ARE SPONSORS OF THE WEEK IN 
ARKANSAS.

TODAYS TOPIC IS A GENERAL OVERVIEW OF LIGHTNING.

LIGHTNING IS THE UNDERRATED KILLER.

LIGHTNING IS FASCINATING TO WATCH BUT ALSO EXTREMELY DANGEROUS. 
IN THE UNITED STATES...THERE ARE ABOUT 23 MILLION LIGHTNING FLASHES
PER YEAR. WHILE LIGHTNING FATALITIES HAVE DECREASED OVER THE PAST
30 YEARS...LIGHTNING CONTINUES TO BE ONE OF THE TOP STORM RELATED
KILLERS IN THE UNITED STATES. IN ADDITION...LIGHTNING INJURES MANY
MORE PEOPLE THAN IT KILLS...AND LEAVES SOME VICTIMS WITH LIFE LONG
HEALTH PROBLEMS.

UNDERSTANDING THE DANGERS OF LIGHTNING IS IMPORTANT SO THAT YOU
CAN GET TO A SAFE PLACE WHEN THUNDERSTORMS THREATEN. IF YOU HEAR
THUNDER...EVEN A DISTANT RUMBLE OR A CRACKLING ALOFT...YOU ARE
ALREADY IN DANGER OF BEING A LIGHTNING VICTIM.

HOW THUNDERSTORMS DEVELOP.

ALL THUNDERSTORMS GO THROUGH STAGES OF GROWTH...DEVELOPMENT...
ELECTRIFICATION AND DISSIPATION. THUNDERSTORMS OFTEN BEGIN TO
DEVELOP EARLY IN THE DAY WHEN THE SUN HEATS THE AIR NEAR THE
GROUND AND POCKETS OF WARMER AIR START TO RISE IN THE
ATMOSPHERE. WHEN THESE POCKETS OF AIR REACH A CERTAIN LEVEL
IN THE ATMOSPHERE...CUMULUS CLOUDS START TO FORM. CONTINUED
HEATING CAUSES THESE CLOUDS TO GROW VERTICALLY INTO THE
ATMOSPHERE. THESE TOWERING CUMULUS CLOUDS MAY BE ONE OF THE
FIRST SIGNS OF A DEVELOPING THUNDERSTORM. THE FINAL STAGE OF
DEVELOPMENT OCCURS AS THE TOP OF THE CLOUD BECOMES SHAPED LIKE
AN ANVIL.

AS A THUNDERSTORM CLOUD GROWS...PRECIPITATION FORMS WITHIN THE
CLOUD. A WELL DEVELOPED THUNDERSTORM CLOUD CONTAINS MOSTLY SMALL
ICE CRYSTALS IN THE UPPER LEVELS OF THE CLOUD...A MIXTURE OF 
SMALL ICE CRYSTALS AND SMALL HAIL IN THE MIDDLE LEVELS OF THE
CLOUD...AND A MIXTURE OF RAIN AND MELTING HAIL IN THE LOWER
LEVELS OF THE CLOUD.

AIR MOVEMENTS AND COLLISIONS BETWEEN THE VARIOUS TYPES OF
PRECIPITATION IN THE MIDDLE OF THE CLOUD CAUSE THE 
PRECIPITATION PARTICLES TO BECOME CHARGED. THE LIGHTER ICE
CRYSTALS BECOME POSITIVELY CHARGED AND ARE CARRIED UPWARD
INTO THE UPPER PART OF THE STORM BY RISING AIR. THE HEAVIER
HAIL BECOMES NEGATIVELY CHARGED AND IS EITHER SUSPENDED BY
THE RISING AIR OR FALLS TOWARD THE LOWER PART OF THE STORM.
THESE COLLISIONS AND AIR MOVEMENTS CAUSE THE TOP OF THE
THUNDERSTORM CLOUD TO BECOME POSITIVELY CHARGED AND THE MIDDLE
AND LOWER PARTS OF THE STORM TO BECOME NEGATIVELY CHARGED.

IN ADDITION...A SMALL POSITIVE CHARGE DEVELOPS NEAR THE BOTTOM
OF THE THUNDERSTORM CLOUD. THE NEGATIVE CHARGE IN THE MIDDLE
OF THE THUNDERSTORM CLOUD CAUSES THE GROUND UNDERNEATH TO 
BECOME POSITIVELY CHARGED...AND THE POSITIVELY CHARGED ANVIL
CAUSES THE GROUND UNDER THE ANVIL TO BECOME NEGATIVELY
CHARGED. 

HOW LIGHTNING FORMS.

LIGHTNING IS A GIANT SPARK OF ELECTRICITY IN THE ATMOSPHERE OR
BETWEEN THE ATMOSPHERE AND THE GROUND. IN THE INITIAL STAGES OF
DEVELOPMENT...AIR ACTS AS AN INSULATOR BETWEEN THE POSITIVE AND
NEGATIVE CHARGES IN THE CLOUD AND BETWEEN THE CLOUD AND THE
GROUND...HOWEVER...WHEN THE DIFFERENCES IN CHARGES BECOME TOO
GREAT...THIS INSULATING CAPACITY OF THE AIR BREAKS DOWN AND
THERE IS A RAPID DISCHARGE OF ELECTRICITY THAT WE KNOW OF AS
LIGHTNING.

LIGHTNING CAN OCCUR BETWEEN OPPOSITE CHARGES WITHIN THE 
THUNDERSTORM CLOUD /INTRA CLOUD LIGHTNING/ OR BETWEEN OPPOSITE
CHARGES IN THE CLOUD AND ON THE GROUND /CLOUD TO GROUND
LIGHTNING/. CLOUD TO GROUND LIGHTNING IS DIVIDED INTO TWO
DIFFERENT TYPES OF FLASHES DEPENDING ON THE CHARGE IN THE 
CLOUD WHERE THE LIGHTNING ORIGINATES.

WHAT IS THUNDER.

THUNDER IS THE SOUND MADE BY A FLASH OF LIGHTNING. AS
LIGHTNING PASSES THROUGH THE AIR...IT HEATS THE AIR QUICKLY.
THIS CAUSES THE AIR TO EXPAND RAPIDLY AND CREATES THE SOUND
WAVE THAT WE HEAR AS THUNDER. NORMALLY...YOU CAN HEAR THUNDER
ABOUT 10 MILES FROM A LIGHTNING STRIKE. SINCE LIGHTNING CAN
STRIKE OUTWARD 10 MILES FROM A THUNDERSTORM...IF YOU HEAR
THUNDER...YOU ARE LIKELY WITHIN STRIKING DISTANCE OF THE 
STORM.

LIGHTNING SAFETY.

THERE IS NO SAFE PLACE OUTSIDE WHEN THUNDERSTORMS ARE IN THE
AREA. IF YOU HEAR THUNDER...YOU ARE LIKELY WITHIN STRIKING
DISTANCE OF THE STORM. JUST REMEMBER...WHEN THUNDER ROARS...
GO INDOORS! TOO MANY PEOPLE WAIT FAR TOO LONG TO GET TO A
SAFE PLACE WHEN THUNDERSTORMS APPROACH. UNFORTUNATELY...
THESE DELAYED ACTIONS LEAD TO MANY OF THE LIGHTNING DEATHS
AND INJURIES IN THE U.S.

THE BEST WAY TO PROTECT YOURSELF FROM LIGHTNING IS TO AVOID
THE THREAT. YOU SIMPLY DO NOT WANT TO BE CAUGHT OUTSIDE IN A
STORM. HAVE A LIGHTNING SAFETY PLAN...AND CANCEL OR POSTPONE
ACTIVITIES EARLY IF THUNDERSTORMS ARE EXPECTED. MONITOR
WEATHER CONDITIONS AND GET TO A SAFE PLACE BEFORE THE WEATHER
BECOMES THREATENING. SUBSTANTIAL BUILDINGS AND HARD TOPPED
VEHICLES ARE SAFE OPTIONS. RAIN SHELTERS...SMALL SHEDS...
AND OPEN VEHICLES ARE NOT SAFE.

A SAFE SHELTER FROM LIGHTNING IS EITHER A SUBSTANTIAL 
BUILDING OR AN ENCLOSED METAL VEHICLE. A SAFE BUILDING IS 
ONE THAT IS FULLY ENCLOSED WITH A ROOF...WALLS...AND FLOOR...
AND HAS PLUMBING OR WIRING. EXAMPLES INCLUDE A HOME...
SCHOOL...CHURCH...HOTEL...OFFICE BUILDING...OR SHOPPING
CENTER. ONCE INSIDE...STAY AWAY FROM SHOWERS...SINKS...
BATH TUBS...AND ELECTRONIC EQUIPMENT SUCH AS STOVES...
RADIOS...CORDED TELEPHONES...AND COMPUTERS.

UNSAFE BUILDINGS INCLUDE CARPORTS...OPEN GARAGES...COVERED
PATIOS...PICNIC SHELTERS...BEACH PAVILIONS...GOLF
SHELTERS...TENTS OF ANY KIND...BASEBALL DUGOUTS...SHEDS...
AND GREENHOUSES.

A SAFE VEHICLE IS ANY FULLY ENCLOSED METAL TOPPED VEHICLE
SUCH AS A HARD TOPPED CAR...MINIVAN...BUS...TRUCK...ETC.
WHILE INSIDE A SAFE VEHICLE...DO NOT USE ELETRONIC DEVICES
SUCH AS RADIO COMMUNICATIONS DURING A THUNDERSTORM. IF YOU
DRIVE INTO A THUNDERSTORM...SLOW DOWN AND USE EXTRA CAUTION.
IF POSSIBLE...PULL OFF THE ROAD INTO A SAFE AREA. DO NOT
LEAVE THE VEHICLE DURING A THUNDERSTORM.

UNSAFE VEHICLES INCLUDE GOLF CARTS...CONVERTIBLES...
MOTORCYCLES...OR ANY OPEN CAB VEHICLE.

LIGHTNING VICTIMS.

IF SOMEONE IS STRUCK BY LIGHTNING...THEY MAY NEED IMMEDIATE
MEDICAL ATTENTION. LIGHTNING VICTIMS DO NOT CARRY AN
ELECTRICAL CHARGE AND ARE SAFE TO TOUCH. CALL 911 AND 
MONITOR THE VICTIM. START CPR OR USE AN AUTOMATED
EXTERNAL DEFIBRILLATOR IF NEEDED.

&&

ADDITIONAL INFORMATION ON LIGHTNING SAFETY IS AVAILABLE ON THE
INTERNET AT WWW.SRH.NOAA.GOV/LZK

$$

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