Transcript HURRICANES
HURRICANES The Atmosphere's Largest Event Presented by: Catherine Charnawskas & Margaret Milligan July 31, 2004 SCE 6103 Storm Types Tropical Storm • Tropical cyclone with 39 to 74 mph winds • Forms over a tropical ocean • Center of the storm is warmer than surrounding air • Strongest winds near Earth’s surface • Has no fronts • 200 to 500 miles wide Extratropical Storm • Dominant weather systems of continents • Forms outside the tropics • Center of the storm is cooler than the surrounding air • The strongest winds are in the upper atmosphere • Has fronts – warm and cold • 700 to 1000 miles wide What is a Hurricane? A hurricane is a tropical cyclone with winds greater than 74 mph. The typical hurricane width is 300 miles across. How to make a hurricane •One part warm ocean water •Above 80° F & 200 ft deep •One part warm and humid air •One part weak upper level winds •Lots of energy! 3% of a hurricane’s energy is transferred into wind and waves. Typhoons and Indian Ocean Cyclones are related to hurricanes. Hurricanes can easily last more than a week. Atlantic hurricanes can devastate Caribbean islands several days before hitting the United States mainland. How a hurricane develops Hurricane season in the Atlantic ranges from June to November with the peak in September. 1. A tropical depression forms over warm ocean water. This will eventually develop into a tropical storm. 2. Humid air rises. 3. When water vapor in rising air condenses into water droplets it releases heat. This is called latent heat. 4. Latent heat warms surround air making it lighter. 5. The lighter air rises. 6. As warm air rises, more air flows in to replace it. This causes wind. 7. On the advancing side of the storm, smaller thunderstorms, tornadoes, and other inclement weather is generated. 8. The eye of the hurricane is calm with wind speeds at nearly zero mph. The pressure in the eye is far below normal sea level pressure. Looking up through the eye of the hurricane an observer will see cloudless skies. Anatomy of a Hurricane Day Twelve: The hurricane continues to weaken after hitting land often called extratropical at this stage. Where can I find a Hurricane? Each year about 100 tropical storm form in the world. 66% develop into hurricanes (Atlantic/East Pacific), typhoons (West Pacific), or cyclones (Indian Ocean). 30% Western North Pacific Ocean 12% South Pacific Ocean 7% North and West Australia 15% East Pacific Ocean 12% North Indian Ocean 12% Western Atlantic Ocean 12% South Indian Ocean Naming Hurricanes Names are different for each region. Names are both male and female. Names are alphabetical and alternate between male and female. 2004 Alex Bonnie Charley Danielle Earl Frances Gaston Hermine Ivan Jeanne Karl Lisa Matthew Nicole Otto Paula Richard Shary Tomas Virginie Walter 2005 Arlene Bret Cindy Dennis Emily Franklin Gert Harvey Irene Jose Katrina Lee Maria Nate Ophelia Philippe Rita Stan Tammy Vince Wilma 2006 Alberto Beryl Chris Debby Ernesto Florence Gordon Helene Isaac Joyce Kirk Leslie Michael Nadine Oscar Patty Rafael Sandy Tony Valerie William Experience shows that the use of short, distinctive given names in written as well as spoken communication is quicker and less subject to error than the older more cumbersome latitude-longitude identification methods. These advantages are especially important in exchanging detailed storm information between hundreds of widely scattered stations, coastal bases, and ships at sea. Saffir-Simpson Scale Saffir-Simpson Scale Strength Category 1 Category 2 Category 3 Category 4 Category 5 Wind Speed Storm Surge Pressure (MPH) (Feet) (Millibars) DID YOU KNOW? Hurricane forecasters consider New Orleans America’s most dangerous for storm surge, since a storm could drive 20ft of water into the city. 74- 95 mph 4-5 feet >980 mb 96-110 mph 6-8 feet 965-979 mb 111-130 mph 9-12 feet 945-964 mb Hurricane Watch – threat within 24-36 hours Hurricane Warning – threat within 24 hours or less 131-155 mph 13-18 feet 920-944 mb >155 mph 18+ feet 919 mb Hurricanes...Devastating? The low pressure and high winds associated with hurricanes create huge mounds of water called STORM SURGES which cause 90% of all hurricane deaths. Hurricane winds have been recorded at speeds up to 200 mph. Beyond the direct damage by such winds, wind-driven waves on top of the storm surge compound the flooding problem by battering and eroding the coastal landscape and structures. Two devastating factors of a hurricane: Storm surge – a huge mound of water created by the low pressure and strong winds of a hurricane. They are found especially in shallow coastal waters. They can increase the water level as much as 20 feet! Wind damage – damage caused by high winds as well as waves driven by high winds. Hurricane Mitch Facts about Mitch •Oct 22 – Nov 9, 1998 •Category 5 •Lowest pressure: 905mb •Highest winds: 180mph •Rainfall: between 300 and 1800mm. •1200 mm recorded in one day in Honduras. This is the yearly average for New England! Strongest hurricane since the Great Hurricane of 1780! Hurricane Mitch Facts about Mitch • Death toll of about 11,000 • Thousands missing • 3 million homeless • $5 billion in damages • Starvation, Malaria, and Cholera were widespread • Crop loss estimated at $900 million • Estimated that it will take 15 to 20 years to rebuild parts of Honduras. Text References Demillo, Rob. How Weather Works Ziff-Davis Press, Emeryville, California 1994, 121-129 Williams, Jack. The Weather Book 1st Edition 1992 Vintage Books, New York, New York, 131-151 American Meteorological Society Project Atmosphere “Hazardous Weather Teacher’s Guide” 1992 pg 21-24 Allaby, Michael. How the Weather Works Reader’s Digest, Pleasantville, New York. 1995. 84-87 Internet Sources/Resources • http://www.weather.com – The Weather Channel • http://www.weatherbug.com – WeatherBug. A downloadable program that gives you current weather for your area. Great way for students to collect weather data over time. • http://www.miamisci.org/ - Great site for hurricane information and activities (and other areas of science too!) • http://www.nws.noaa.gov/ - National Weather Service • http://www.wunderground.com – Weather Underground, another great site for collecting weather data around the United States and world.