000 NOUS44 KLZK 201104 PNSLZK ARZ003>007-012>016-021>025-030>034-037>047-052>057-062>069-201900- PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE LITTLE ROCK AR 600 AM CDT MON JUN 20 2011 ...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 25 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. SUBSTANIAL 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 $$ 28