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SEVERE WEATHER NOTES By Laura LeMay What causes everyday weather and storms? •Air Pressure •Air Masses STORM: • Violent disturbance in atmosphere • Caused by sudden change in AIR PRESSURE Angels enjoying HOT CHOCOLATE with lots of marshmallows!!!!!! A. THUNDERSTORM characteristics • Heavy rain with thunder and lightning • Form in large CUMULONIMBUS CLOUDS • form when WARM air is forced upward at COLD front. • Humid afternoons in SPRING and SUMMER 2. WINDS • Strong upward and downward winds called updrafts and downdrafts • Downdrafts cause WIND SHEAR • Can exceed 160 km/hr cumulonimbus LIGHTNING • Sudden spark of energy • May heat air as much as 30,000 C http://physics-animations.com/Physics/English/ligh_txt.htm Thunder •Rapidly heated air •EXPLOSIVE!! •Travels slower than lightning Thunderstorm Video • http://www.metacafe.com/watch/1393752/ awesome_thunderstorm/ How far is the storm • • • 1) Count # between see lightning and hear thunder 2) Divide that number by 3 FORMULA: 15 secs 3 s/km a)9 secs c) 3 secs b) 21 secs d) 30 secs SAFETY • Avoid metal (CONDUCTION) • LIGHTNING RODS on large buildings towers • Get into LOW AREA away from trees, poles… • Get away from WATER • In house avoid using ELECTRICAL DEVICES Lightning rod Fast fact: • The Empire State Building is designed to serve as a lightning rod for the surrounding area. It is struck by lightning about 100 times per year. 7. FACTS: • 16 million thunderstorms a year • Every minute 100 bolts of lightning strike Earth • Kills 70 people/ year • 300 + are injures • Last 10 years started 15,000 fires lightning Sudden change in pressure Cold and hot air masses thunder thunderstorms Humid afternoons in spring/summer (mostly) Cumulonimbus Clouds Updrafts and downdrafts of wind B. TORNADO • Rapid, whirling, funnel shape cloud that reaches land. • Over Lake/Ocean= WATERSPOUT Characteristics • Brief but DEADLY • (15 minutes or less) • Winds may reach 480 km/hr HOW FORM? • Low, Heavy CUMULONIMBUS clouds • In SPRING and SUMMER • usually in late AFTERNOON • SQUALL LINES form where warm and cold FRONTS meet. 4. TORNADO SAFETY: • “WATCH” : tornados possible • “WARNING: tornado has been spotted Get in BASEMENT of well built building MIDDLE OF GROUND FLOOR away from WINDOWS AND DOORS Lie under STURDY FURNITURE GET OUT of mobile home and lie flat in DITCH Tornado Video • http://video.nationalgeographic.com/video/ environment/environment-naturaldisasters/tornadoes/tornadoes-101/ 5. Tornado Facts • 800 occur per/ yr in the US • “tornado alley” great plains region-North Central Texas across Oklahoma. Where COLD air meets WARM air High humidity Spring and summer afternoon Squall lines Cumulonimbus clouds tornado Cold air meets warm air Brief but deadly Spiral/funneling winds thunderstorms C. Hurricane •Tropical Storm with winds 119 mph or greater 1. Characteristics: • Occur between JUNE and NOVEMBER • Typically 600 km across(300+ miles) • Atlantic= HURRICANE • In Pacific/Indian Ocean= TYPHOON • Bring destruction/ but needed rainfall to S and SE Asia • May last 1 WEEK or longer 2. How FORMS: • Begin over WARM water as LOW pressure system. Begins as tropical depression • Grows larger = TROPICAL STORM HURRICANE • ENERGY comes from warm water/humid air • Air RISES and produces clouds (called?) • WINDS spiral in toward LOW pressure • CENTER= low pressure and warm temperatures • Faster WINDS towards center 3. How Hurricanes Move: • Carried by the TRADE winds towards Caribbean and SE United States • FRICTION on land slows down storm 4. Key Points: • EYE= calm center of the storm with ring of clouds surrounding • Winds REVERSE in OPPOSITE direction after eye of the storm passes. 7. RANKING 5. DAMAGE • Severe FLOODING • WIND damage • High waves • STORM SURGE= most dangerous part of storm (can raise sea level 6 meters) • “DOME” of water sweeps across land Hurricane Video!! • http://video.nationalgeographic.com/video/ environment/environment-naturaldisasters/hurricanes/hurricane-montage/ 6. SAFETY • “WATCH”- possible within 36 hours= prepare to leave • “WARNING”- expected with 24 hours= –EVACUATE –If stay= board house/ stay in interior 8. HISTORY • June 1972= AGNES- severe flooding in NC to NY. 17 tornados in Florida and Georgia • AUG 1992= ANDREW - $25 billion damage – second-most-destructive hurricane in U.S. history • Aug 1999 = FLOYD=extensive flood damage and coastal damage. • AUG 2005 = Hurricane Katrina was the costliest and one of the five deadliest hurricanes in the history of the United States PHOTOS: Warm water Rain/Major flooding June to November tornadoes Eye=calm center hurricane Avg. 300 miles across Low pressure system May last weeks High winds-reverse after eye D. WINTER STORMS: • Northeastern US high risk • ROCHESTER and BUFFALO, NY get an average of 3 METERS/year • LAKE-EFFECT Snows: – Cold dry air – Travels over – Lake and – Drops heavy – Snowfall – when – cools Lake Effect Video • http://www.accuweather.com/en/weathervideo/lake-effect-snow/1261938918001 SAFETY: • If in storm SEEK SHELTER • Cover all exposed areas (remember: WIND CHILL) • STAY DRY • Car: CLEAR EXHAUST (or CO poisoning) Heavy snowfall Blizzard/whiteouts Winter storm Convection/evaporation /condensation May cause flooding in spring melting Winter season /precipitation Dry, cold air moves over warm, moist water= lake effect snow E. FLOODING •Too much water pours from streams/rivers that overflow banks and cover land surrounding 1. CHARACTERISTICS: • Rain falls River rises land floods evacuate • FLASH FLOOD: sudden, violent flood within hours/minutes of storm • May Cause MUDSLIDES/LANDSLIDES Flood Video: Atlanta • http://www.floodsmart.gov/floodsmart/page s/videos/video_index.jsp 2. SAFETY • “WATCH” –flooding possible, stay alert • “WARNING”- flooding reported, take action 1)move to HIGHER GROUND away from WATER 2) Do not cross/play in STREAMS/DRAINS 3) Do not drive on FLOODED roads 4) BOIL water if possible contamination May occur in thunderstorms/tornados/hurricanes/winter storms flooding Mudslides/landslides Too much water in a short amount of time= flash flood