Major Storm Ss Three Major Type of Storms Thunderstorm

Major Storms Chapter 10 continued Three Major Type of Storms Thunderstorms

Hurricanes

Tornadoes

Thunderstorm Brief, but intense, storm with rain, lightning and thunder, gusty and often strong winds, and sometimes hail Develop in warm, very moist, and unstable air Thunderstorm Stages Cumulus Stage

Mature Stage

Dissipating Stage Cumulus Stage Heat from earth’s surface warms the air around it The warm air rises (updraft) Moist air condenses to form cumulus cloud Cloud grows in height as long as warm moist air rises Mature Stage Large cumulus cloud has heavy, large water droplets which fall Cool ,dry air enters cloud and descends (downdraft) Pulls water droplets downward forming rain Mature Stage Cumulus cloud has become cumulonimbus It has updraft, downdraft, and precipitation Lightning and thunder begin Dissipating Stage Downdrafts begin to dominate the updrafts Prevents warm, moist air from rising and forming cloud droplets Storms dies out with light rain Lightning Giant electrical discharge that occurs when the insulating ability of air separating positive and negative charges breaks down Lightning In thunderstorm, electric charge is separated Positive charges at top of cloud Negative charges at bottom Earth’ surface has positive charge

Charge at bottom of cloud overcomes air resistance from updrafts

Lightning Negative charge rushes toward earth (stepped ladder) Positive charge from earth flows into air and meets negative charge Current carries positive charge up into cloud THIS CURRENT IS LIGHTNING WE SEE!! Fort Smith, Arkansas Thunder Lighting discharge produces extremely high temperatures – 54,000 deg F Travels through air and heats it quickly –causing it to expand at explosive rate Expansion creates shock wave that creates booming sound—THUNDER!! LIGHTNING CAUSES THUNDER!!!!! Hurricanes Large, violent circular storm that develops over the warm, tropical ocean near the ______Hurricane They are cyclonic Winds swirl around central eye Wind direction ______– in ______Hemisphere ______– in ______Hemisphere Hurricane They are low-pressure systems. Eye of a hurricane is always low-pressure area. Lowest barometric pressures ever recorded have occurred inside hurricanes. Hurricane Wind speed At center of storm must be sustained ______Hurricane Season ______through ______Stage of Formation Tropical wave – wind speeds less than 25 mph Lacks closed circulation Tropical depression – sustained winds between 25 – 39 mph System still disorganized ______– winds are sustained _____-74 mph Closed circulation Hurricane – winds sustained 74 mph or greater Closed circulation becomes eye Factors in Hurricane Development ____________or greater Fuel source is the moist, warm air Light westerly winds aloft hurricanes travel east to west so light westerly winds prevent shearing and tearing apart of thunderstorms Rotation (spin) Without spin, the wave is just another area of low pressure Hurricane Formation Low atmospheric area moves off ______and into the Atlantic Air moves toward these atmospheric lows from all directions and curves under the influence of the Coriolis Effect, initiating rotation Hurricane Formation Hot, moist air masses meet and rise up into the atmosphere above the low pressure area, establishing a self-reinforcing feedback system Parts of Hurricane _____ - the low pressure, calm center of circulation ______- area around the eye with the fastest, most violent winds ______- bands of thunderstorms circulating outward from the eye Part of the evaporation/condensation cycle that feeds the storm Hurricane Damage huge amounts of rain

high sustained winds

storm surge - wall of water

tornadoes ______-______(know there are 5 categories) Category 1 -wind speed (_____ - 95 mph) Category 2 - wind speed (_____ - 110 mph) Category 3 - wind speed (_____ - 130 mph) Category 4 - wind speed (_____ - 155 mph) Category 5 - wind speed ( > _____ mph) little or no structural damage and some flooding trees down and roof damage (shingles ripped off) mobile homes damaged and severe flooding major structural damage and severe inland flooding serious damage to most wood structures and severe flooding further inland Historic Hurricanes ______hurricane Hurricane ______October 19, 2005 Lowest pressure 884 mb Highest wind speed 175 mph Dropped in pressure from 970 mb to 884 mb and increased wind speed from 80 mph to 175 mph in a 12 hour period

Strongest Hurricanes Tornadoes A tornado is defined as a violently rotating column of air in contact with the ground and pendent from a ______cloud ______disturbance on Earth Tornado Formation Violent updrafts and strong winds combine and form whirling vortex of air Updrafts tilt it vertically Air must be blowing in same direction at all levels of atmosphere How Tornadoes Form one way the rotation appears to happen is when winds at two different altitudes blow at two different speeds creating wind shear How rotation begins is still not completely understood by scientists How Tornadoes Form column gets caught in a supercell updraft, the updraft tightens the spin and it speeds up (like a skater's spins faster when arms are pulled close to the body) funnel cloud is created. How Tornadoes Form rain and hail in the thunderstorm cause the funnel to touch down creating a tornado Tornado Trivia ______reported per year in United States Can last few seconds to an hour Can remain on ground from a few yards to 100 miles Tornado Trivia Most tornadoes occur in ______

99% rotate counterclockwise in Northern Hemisphere

Most tornadoes occur in the ______Tornado Trivia

occur most frequently in the U.S. between 4 and 6 p.m. average 5 to 10 minutes on the ground. can stand still or move forward up to 70 mph. can be up to a mile wide at ground level. Multiple Choice Q: What is the safest thing to do during a tornado? Leave all windows open to prevent them from breaking Leave all windows closed to keep pressure from building against the roof of the structure.

Multiple Choice (KNOW) Q: What is the safest thing to do during a tornado?

Leave all windows closed to keep pressure from building against the roof of the structure.

______

______for tornadoes in US Tornado Alley The land in the Great Plains is relatively flat, which allows cold dry polar air from Canada to meet warm moist tropical air from the Gulf of Mexico. It's along the front between the two air masses that most tornadoes form. Fujita Scale

______Scale (know categories)

(February 1, 2007)  aligns wind speeds more closely with associated storm damage  takes into account quality of construction and standardizes different kinds of structures

Historic Tornadoes Huntsville, Alabama Tornado (Nov 15, 1989) 259 Homes destroyed 130 Homes with major damage 148 Homes with minor to moderate damage 80 Businesses destroyed 8 Businesses damaged 3 Churches heavily damaged 2 Schools destroyed 10 Public buildings destroyed or heavily damaged $1.9 Million in public utility damage $160 million total damages Historic Tornadoes Huntsville, Alabama Tornado F4 tornado 21 fatalities 463 injured Birmingham Tornado of 1998 Occurred April 8, 1998 F5 category Over 1,000 homes and businesses were destroyed. 33 people killed and 256 injured th 7 deadliest in Alabama history

B’ham tornado damage B’ham tornado damage December 16, 2000 Tuscaloosa Tornado F4 tornado Forward speed of 60 mph 11 fatalities and 143 injured 300 homes damaged http://www.youtube.com/watch?v=G3Jyqy7qhsQ

Tuscaloosa tornado damage Tuscaloosa tornado damage

Remains of mobile home ______March 21, 1932 Affected Perry, Bibb, Chilton, Shelby, Coosa counties 60 mile path 800 yards wide F4 category ______and 150 injured

Historic Tornadoes ______(April 3-4, ______) 148 tornadoes in 13 states ______in US Historic Tornadoes Super Outbreak 315 – 330 fatalities 28 deaths in Guin, ____________tornado Destroyed entire town ______of Super Outbreak (traveled over 100 miles)

______, ____________during ______started in southwest Greene County just outside the Dayton area at about 3:30PM CDT. Started as a small tornado and intensified while moving northeast at about 50 mph. In early stages, two tornadoes were formed and merged into the main one Two Tornadoes Xenia tornado Xenia Tornado Damage

 Langs Chevrolet Used Cars Covington Co. Tornadoes MAY 03, 1956 F3 JUN 28, 1957 F2 JAN 05, 1962 F2 DEC 24, 1964 F0 NOV 11, 1974 F1 MAR 13, 1975 F1 MAR 31, 1976 F2 MAY 03, 1978 F1 JLY 11, 1979 F2 MAY 20, 1980 F1 MAY 20, 1980 F1 DEC 28, 1983 F2 JUN 13, 1984 F1 SEP 15, 1984 F1 OCT 28, 1985 F1 FEB 22, 1990 F1 JAN 01, 1994 F0 MAY 09, 1995 F0 OCT 04, 1995 F0 OCT 04, 1995 F0 OCT 04, 1995 F0 … NOV 15, 2006 F2 Deadliest Tornado in US March 18, 1925 695 fatalities and 2027 injured F5 category MO, IL, IN states affected Tornado Myths (KNOW) Opening windows will equalize air pressure and prevent an explosion

 TRUE FALSE

Fact: Most experts agree that tornado-force winds will take care of opening the windows for you. Forget this old advice. Take cover immediately!

Tornado Myths (KNOW) Go to the Southwest Corner of your Basement

TRUE FALSE

Fact: Some studies suggest this might actually be the most dangerous place in your basement. If a tornado hits from the southwest, it could push debris into that area. No matter where you go, try to hide under a mattress or sturdy piece of furniture to maximize protection.

Tornado Myths (KNOW) Tornadoes never strike big cities

 TRUE FALSE

Fact: In the past several years, tornadoes have roared through several major cities including Miami, Nashville, Tenn, and Fort Worth, Texas. Despite folklore, no city or town has "Natural Protection" from a tornado.

Tornado Myths (KNOW) Highway overpasses are adequate shelter if a tornado approaches while you are on a road. TRUE FALSE Sensational footage taken by a television crew hiding from a tornado under an overpass during the 1991 Andover, KS Tornado Outbreak helped to convince some that bridges are good shelters when a tornado is nearby. The members of the television crew (and several other travelers) survived by huddling high underneath the bridge and bracing themselves against support columns while a weak tornado appeared to pass directly over the bridge. FACT: In reality, when directly hit by tornadoes, the confined spaces beneath overpasses increase the speed of the winds due to the Venturi Effect and thus make them potentially less safe. In the case of the Andover tornado footage, it was discovered that the tornado did not pass directly over the bridge, but instead over the ground slightly south of the bridge and camera crew, exposing them to much weaker winds. Tornado Myths (KNOW) Twisters are attracted to mobile homes and/or trailer parks.  TRUE FALSE FACT: Trailer parks consist of mobile homes with less structural integrity than traditional houses. A weak storm that leaves little damage to well-built structures might devastate a trailer park. Mobile homes do not attract tornadoes; they are just more susceptible to damage from them. Tornado Myths Tornadoes cannot form near rivers or cross them. FACT: During the Super Outbreak, a tornado formed near Sayler Park section of Cincinnati, Ohio (near the Ohio River). It was among the six F5s of the outbreak. The city of Cairo, Illinois, which lies at the confluence of the Ohio and Mississippi Rivers, was also hit by a tornado that day. FACT: The Tri-state tornado of 1925 crossed the Mississippi and possibly several other small bodies of water. FACT: The F5 tornado of May 3, 1999 crossed the Yukon River in Oklahoma before it hit Moore, Oklahoma. Tornado Myths Tornadoes cannot follow terrain into steep valleys or travel over steep hills or mountains. FACT: During the Super Outbreak, the Guin tornado crossed Monte Sano mountain (1,650 feet) and gained in intensity as it descended the mountain. An F4 tornado caused damage in Murphy, NC after crossing a 3,000-foot ridge, and F2 tornadoes were confirmed in Roanoke, VA and Great Smokey Mountains National Park, NC. Tornadoes formed elsewhere in West Virginia, western Virginia, southwestern North Carolina, and north Georgia - regions of four states that are in the ranges of the Appalachian Mountains. Also, it's not too high for a tornado. In Salt Lake City, Utah, a tornado formed and damaged a streak of the city near downtown. Salt Lake City is well above 4000 feet. However, it should be noted that it is a rare occurrence for tornadoes to form west of the Rocky Mountains. Tornado Oddities Great Bend, Kansas tornado November 1915 check from Great Bend was found in a corn field, one mile outside of Palmyra, Nebraska...305 miles to the northeast, the longest known distance that debris has ever been carried Tornado Oddities A necktie rack with 10 ties still attached was carried 40 miles A flour sack from the Walnut Creek Mill was found 110 miles to the northeast Dead ducks fell from the sky 40 miles northeast of that migratory bird refuge Iron water hydrant was found full of splinters ―Twister‖ (1996 movie)

air and debris whooshes in toward the tornado, not out, with debris, 18-wheel oil trucks, farm equipment, cows and houses being flung away. the stars' hair should have been blowing forward, not back ―Twister‖ tornadoes wander, alter their path and change in intensity, but they don't skitter back and forth across roads like jittery rabbits, take sudden U-turns or drop out of sunny and virtually windless skies. "Whooeee! We've got ourselves an F3!" Category can only be determined when damage is assessed ―Twister‖ Cloud formations also are wrong Movie shows tornadoes forming out of stratus clouds Chasers don't get in the way of tornadoes, let alone drive a speeding van or stand 50 yards from one "It's insane. Just absolutely unbelievably insane," said Richard Thompson, who has chased down 40 to 50 tornadoes ―Twister‖ People don’t survive tornadoes by tying themselves to underground pipes. At the very least, the characters of Jo and Bill would have been knocked unconscious and severely wounded by all the debris flying around. Tornado Prediction (a tough job) Meteorologists use info from atmospheric conditions of past tornadoes Meteorologists send up weather balloons to take what is called a sounding of the atmosphere Measures atmospheric stability, temperature, and humidity Look for high humidity and high instability Tornado Prediction Using ______can detect a tornado as it's forming--up to 20 minutes before it touches down can figure out how far away a raindrop is and it can also calculate if it's moving toward or away from the radar. I If the rain is moving, then the wind must be pushing it and this tells where the wind is blowing in clouds.

Indiana -- April 11, 1965 (Palm Sunday Outbreak)