Natural Disasters Vocabulary natural disaster hurricane tornado storm surge droughts flood wildfire sink hole model Evidence earthquake* tsunami* volcanic eruption* convergent boundaries* divergent boundaries* transform boundaries* Natural Disasters Hurricanes Word originates from the Greek word cyclone which translates to an object moving in a circle. They are called tropical cyclones but in the North Atlantic ocean and Eastern Pacific they are referred to as Hurricanes. Hurricanes Hurricanes are very large and violent tropical storms, which can start as small thunderstorms over warm water as air pressure at the oceans surface drops. Heat from the water fuels the storm and can cause winds and moisture to swirl upward and increase its strength. How are hurricanes formed ? There are specific conditions that must be present in order for a hurricane to develop: Water Temperature: warm waters (at least 80 F) thru a depth of about 150 ft. Humidity: moist air near the troposphere Location: minimum distance of 300 miles from the equator (5 N 30 N) Wind: low- mid shear winds (23mph or less), with winds facing vertically in same direction Air Pressure: low Parts of the Hurricane Hurricanes (cont.) Hurricanes usually form early summer when the sun heats huge masses of moist air up until the end of fall (June November). SEE DEMOSTRATIONSEE DEMOSTRATION #1 SEE DEMOSTRATIONSEE DEMOSTRATION #2 The calm center of a hurricane is called the eye. Although, this is also the most dangerous part, since the eye wall surrounding it has high winds. WATCH HURRICANE AND WEATHER VIDEO Tracking a Hurricane: We can track the path of a hurricane at home if we know how to use a map to find coordinates. Longitude lines are those that run vertically (up and down) use east and west to describe. Ex. y axis Latitude lines are those that run horizontally (side to side) use north and south to describe. Ex. X axis Tracking a Hurricane: When you write coordinates you first write latitude first then longitude. You must also include direction (N,S, E, W) because there are two of every coordinate; above and below the equator Lets practice (25N, 80W) (19N, 70W) Hurricane Hunters Hurricane Hunters use specialized planes that are part of the U.S. Air force assigned to gather information about tropical storms. Their information is sent to the NHC where it is fed into the computer forecast models so that a prediction can be made! National Hurricane Center The National Hurricane Center is responsible for developing a forecast track and issuing any advisories or warnings. They use the information from the Hurricane Hunters GPS sonar. Tracking: in order to create a possible hurricane track, the NHC takes into consideration all conditions surrounding the hurricane such as high and low pressure systems that can change the details of the hurricane. How do we know where the hurricane is going? Forecast Models Statistical Dynamical Model: combines both physics and history to create a forecast model Statistical Models: based on historical relationships between storm behavior and storm specific details (location & date) Dynamical Models: numerical model that uses physics to solve equations of motion in the atmosphere Major Hurricanes Hurricane Andrew: large and ferocious hurricane that brought economic devastation along a path through the northwestern Bahamas, the southern Florida peninsula, and south-central Louisiana large and ferocious hurricane that brought economic devastation along a path through the northwestern Bahamas, the southern Florida peninsula, and south-central Louisiana damage in the United States is estimated to be near 25 billion, making Andrew the 2 nd most expensive natural disaster in U.S. history damage in the United States is estimated to be near 25 billion, making Andrew the 2 nd most expensive natural disaster in U.S. history Major Hurricanes Hurricane AndrewHurricane Andrew: struck southern Dade County, Florida, especially hard, with violent winds and storm surges characteristic of a category 5 hurricane on the Saffir/Simpson Hurricane Scale, and with a central pressure (922 mb) In Dade County, the forces of Andrew resulted in 15 deaths and up to one-quarter million people left temporarily homeless. An additional 25 lives were lost in Dade County from the indirect effects of Andrews aftermath. However, the direct loss of life seems remarkably low considering the destruction caused by this hurricane. Staying Safe in a Hurricane Major dangers: High winds Flooding Pounding waves/Storm Surge Tips to staying safe: Leave areas that are in the path of a hurricane before it strikes Find shelter in a strong brick or stone building on high ground Stay away from windows and doors Keep rope, extra food and water, a flashlight, a battery-operated radio, and if possible corded phone and/or cell phone with you. How are Hurricanes and Tornadoes classified differently? Hurricanes (Saffir-Simpson Scale) Tornadoes (Fujita Scale) Pressure is above 980 with speeds between mph, and storm surges up to 1.5 m (Minimal Damage) Pressure is between with speeds between mph, and storm surges up to 2.5 m (Moderate Damage) Pressure is between with speeds between mph, and storm surges up to 3.7 m (Extensive Damage) Pressure is between with speeds between mph, and storm surges up to 5.5 m (Extreme Damage) Pressure is below 920 with speeds of 156 mph or more, and storm surges up to 5.5 m (Catastrophic Damage) mph Weak tornado mph Moderate tornado mph Strong tornado mph Significant tornado mph Devastating tornado Over 200 mph Devastating/Violent tornado C1 C2 C3 C4 C5 F0 F1 F2 F5 F3 F4 Tornadoes A dark funnel of strong winds that spiral upward, they can reach speed of 500 KPH Can start as a funnel cloud that reaches the Earths surface. Air pressure inside the tornadoes funnel is much lower than the air pressure outside which make it act like a huge vacuum cleaner. The region in the U.S. where most tornadoes occur is called Tornado Alley (central U.S.) Parts of a tornado Becomes tornado once it reaches the ground vortex Funnel cloud How Do Tornadoes Form? #1 two different fronts meet and create a rotating spiral in the atmosphere #2 these winds form a horizontal rotation that then updrafts to a vertical rotation #3 these rotation continues to move faster creating a tornado noaa tornado info. Tornadoes vs. Water Spouts form during the early stages of rapidly developing thunderstorms and forms on ground. may appear nearly transparent until dust and debris are picked up. Occasionally, two or more tornadoes may occur at the same time. weak tornadoes that form over warm water. common along the Gulf Coast and southeastern states. occasionally move inland becoming tornadoes causing damage and injuries. Staying Safe in a Tornado Major dangers: Powerful/Unexpected winds Tips to staying safe: Find shelter in a basement or a tornado cellar Stay clear of outside walls, windows, and doors Get away from cars, mobile homes, and other objects that might be flipped over or thrown by winds If you are outdoors, find shelter in a ditch or cave Cover your head with your arms