A man who carries a cat by the tail learns something he can learn in no other way. Mark Twain Mark Twain

THUNDERSTORMS

THUNDERSTORM - A STORM WITH VISIBLE LIGHTNING AND AUDIBLE THUNDER ON AVERAGE, 1800 THUNDERSTORMS HAPPEN AROUND THE GLOBE DURING ANY DAY.

BECAUSE OF THE TURBULENCE IN A THUNDER CLOUD, THE WATER DROPLETS AND ICE CRYSTALS WILL BREAK APART AND BECOME ELECTRICALLY CHARGED. GENERALLY, THE TOP OF THE CLOUD IS POSITIVELY CHARGED, AND THE MIDDLE AND LOWER PORTIONS ARE NEGATIVELY CHARGED. WHEN THE CHARGES BECOME LARGE ENOUGH, ELECTRICAL DISCHARGES WILL OCCUR.

THE ELECTRICAL DISCHARGE HEATS AIR TO VERY HIGH TEMPERATURES. THIS CAUSES A RAPID EXPANSION OF THE AIR, AND THIS IS THUNDER. THE AIR IS HEATED TO 50,000 o F AND LITERALLY EXPLODES.

BETWEEN 75 AND 100 PEOPLE ARE KILLED EACH YEAR IN THE U.S. FROM LIGHTNING STRIKES. APPROXIMATELY 10,000 FIRES ARE STARTED BY LIGHTNING EACH YEAR. NASA DISCOVERED A HIGH CORRELATION BETWEEN LIGHTNING STRIKES AND THE AMOUNT OF ICE IN CLOUDS.

TORNADO - A VIOLENTLY ROTATING COLUMN OF AIR IN CONTACT WITH THE GROUND THE U.S. AVERAGES 800 TORNADOES PER YEAR. ONLY ABOUT 1% OF THE 100,000 THUNDERSTORMS THAT OCCUR EACH YEAR SPAWN TORNADOES. RISING WARM AIR AND COOL DOWNDRAFTS COMBINE TO FORM AIR IN A HORIZONTALLY ROTATING TUBE. THIS TUBE CAN TILT AND RESULT IN A TORNADO.

TORNADOES USUALLY FORM ON THE TRAILING EDGES OF STORMS.

WEAK TORNADOES WITH WINDS UNDER 110 MPH ACCOUNT FOR 69% OF ALL TORNADOES AND 3% OF ALL TORNADO DEATHS. THEY USUALLY LAST 6 TO 10 MINUTES.

STRONG TORNADOES (WINDS MPH) ACCOUNT FOR 29% OF ALL TORNADOES AND 27% OF ALL TORNADO DEATHS. THEY MAY LAST 20 MINUTES OR LONGER.

VIOLENT TORNADOES (WINDS OVER 205 MPH) ACCOUNT FOR ONLY 2% OF ALL TORNADOES, BUT 70% OF ALL TORNADO DEATHS. THEY CAN LAST OVER AN HOUR.

57 DEATHS AND 1,248 INJURIES

WATERSPOUTS - WEAK TORNADOES THAT OCCUR OVER WATER

WHAT TO DO IN CASE OF A TORNADO. 1.GET INTO A BASEMENT, IF POSSIBLE, UNDER STURDY FURNITURE OR A WORK BENCH 2.GET IN A HALLWAY, CLOSET OR BATHROOM - AN INTERIOR ROOM IS BEST 3.IF OUTSIDE, LIE FLAT IN A DITCH AND COVER YOUR HEAD 4.IF IN A MOBILE HOME, GET IN A BATH TUB WITH A MATTRESS OVER YOU

MOST TORNADO DEATHS OCCUR IN AUTOMOBILES AND MOBILE HOMES.

Comparison of Weather Risks Country Severe Thunderstorm s Tornadoes Severe Winter Storms Hurricanes, Tropical Cyclones, Typhoons Flash Floods U S A10,000/yr1000/yr10/yr 1000/yr Australia500< Canada France100< Germany100< Japan500< United Kingdom Russia/fmr USSR5, China10,000< Data courtesy NOAA, NWS