Tornadoes and hurricanes

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Tornadoes and hurricanes

  1. 1. A tornado is a violent, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. The most intense of all atmospheric phenomena, tornadoes come in many shapes and sizes but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds between 40 mph (64 km/h) and 110 mph (177 km/h), are approximately 250 feet (75 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme can attain wind speeds of more than 300 mph (480 km/h), stretch more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 km).
  2. 2. Tornadoes often begin as funnel clouds with no associated strong winds at the surface, though not all evolve into a tornado. However, many tornadoes are preceded by a funnel cloud. Most tornadoes produce strong winds at the surface while the visible funnel is still above the ground, so it is difficult to discern the difference between a funnel cloud and a tornado from a distance. Occasionally, a single storm will produce more than one tornado, either simultaneously or in succession. Multiple tornadoes produced by the same storm cell are referred to as a "tornado family".Several tornadoes are sometimes spawned from the same large-scale storm system. If there is no break in activity, this is considered a tornado outbreak, although there are various definitions. A period of several successive days with tornado outbreaks in the same general area (spawned by multiple weather systems) is a tornado outbreak sequence, occasionally called an extended tornado outbreak. A wedge tornado, nearly a mile wide. This tornado hit Binger, Oklahoma. Most tornadoes take on the appearance of a narrow funnel, a few hundred yards (meters) across, with a small cloud of debris near the ground. Tornadoes may be obscured completely by rain or dust. These tornadoes are especially dangerous, as even experienced meteorologists might not spot them. Tornadoes can appear in many shapes and sizes. Small, relatively weak landspouts may only be visible as a small swirl of dust on the ground. Although the condensation funnel may not extend all the way to the ground, if associated surface winds are greater than 40 mph (64 km/h), the circulation is considered a tornado. A tornado with a nearly cylindrical profile and relative low height is sometimes referred to as a "stovepipe" tornado. Large single-vortex tornadoes can look like large wedges stuck into the ground, and so are known as "wedge tornadoes" or "wedges". The "stovepipe" classification is also used for this type of tornado, if it otherwise fits that profile. A wedge can be so wide that it appears to be a block of dark clouds, wider than the distance from the cloud base to the ground. Even experienced storm observers may not be able to tell the difference between a lowhanging cloud and a wedge tornado from a distance. Many, but not all major tornadoes are wedges.
  3. 3. The most extreme tornado in recorded history was the Tri-State Tornado, which roared through parts of Missouri, Illinois, and Indiana on March 18, 1925. It was likely an F5, though tornadoes were not ranked on any scale in that era. It holds records for longest path length (219 miles, 352 km), longest duration (about 3.5 hours), and fastest forward speed for a significant tornado (73 mph, 117 km/h) anywhere on Earth. In addition, it is the deadliest single tornado in United States history (695 dead). The tornado was also the second costliest tornado in history at the time, but in the years since has been surpassed by several others if population changes over time are not considered. When costs are normalized for wealth and inflation, it ranks third today. [90] The deadliest tornado in world history was the Daultipur-Salturia Tornado in Bangladesh on April 26, 1989, which killed approximately 1300 people. Bangladesh has had at least 19 tornadoes in its history kill more than 100 people, almost half of the total in the rest of the world.
  4. 4. Hurricane Katrina of the 2005 Atlantic hurricane season was the costliest hurricane, as well as one of the five deadliest, in the history of the United States. Among recorded Atlantic hurricanes, it was the sixth strongest overall. Hurricane Katrina formed over the Bahamas on August 23, 2005 and crossed southern Florida as a moderate Category 1 hurricane, causing some deaths and flooding there before strengthening rapidly in the Gulf of Mexico. The storm weakened before making its second landfall as a Category 3 storm on the morning of Monday, August 29 in southeast Louisiana. It caused severe destruction along the Gulf coast from central Florida to Texas, much of it due to the storm surge. The most severe loss of life occurred in New Orleans, Louisiana, which flooded as the levee system catastrophically failed, in many cases hours after the storm had moved inland. Eventually 80% of the city and large tracts of neighboring parishes became flooded, and the floodwaters lingered for weeks. However, the worst property damage occurred in coastal areas, such as all Mississippi beachfront towns, which were flooded over 90% in hours, as boats and casino barges rammed buildings, pushing cars and houses inland, with waters reaching 6–12 miles (10–19 km) from the beach.
  5. 5. At least 1,836 people lost their lives in the actual hurricane and in the subsequent floods, making it the deadliest U.S. hurricane since the 1928 Okeechobee hurricane. Hurricane Katrina in 2005 was the largest natural disaster in the history of the United States. Total damage was $81 billion (2005 USD), nearly triple the damage wrought by Hurricane Andrew in 1992. Katrina redistributed over one million people from the central Gulf coast elsewhere across the United States, which became the largest diaspora in the history of the United States. Houston, Texas, had an increase of 35,000 people; Mobile, Alabama, gained over 24,000; Baton Rouge, Louisiana, over 15,000; and Hammond, Louisiana received over 10,000, nearly doubling its size. Chicago received over 6,000 people, the most of any non-southern city. By late January, 2006, about 200,000 people were once again living in New Orleans, less than half of the pre-storm population. By July 1, 2006, when new population estimates were calculated by the U.S. Census Bureau, the state of Louisiana showed a population decline of 219,563, or 4.87%. Additionally, some insurance companies have stopped insuring homeowners in the area because of the high costs from Hurricanes Katrina and Rita, or have raised homeowners' insurance premiums to cover their risk.
  6. 6. All three coastal counties of the state were severely affected by the storm. Katrina's surge was the most extensive, as well as the highest, in the documented history of the United States; large portions of both Hancock, Harrison, and Jackson Counties were inundated by the storm surge, in all three cases affecting most of the populated areas. Surge covered almost the entire lower half of Hancock County, destroying the coastal communities of Clermont Harbor and Waveland, much of Bay St. Louis, and flowed up the Jourdan River, flooding Diamondhead and Kiln. In Harrison County, Pass Christian was completely inundated, along with a narrow strip of land to the east along the coast, which includes the cities of Long Beach and Gulfport; the flooding was more extensive in communities such as D'Iberville, which borders Back Bay. Biloxi, on a peninsula between the Back Bay and the coast, was particularly hard hit, especially the low-lying Point Cadet area. In Jackson County, storm surge flowed up the wide river estuary, with the combined surge and freshwater flooding cutting the county in half. Remarkably, over 90% of Pascagoula, the easternmost coastal city in Mississippi, and about 75 miles (121 km) east of Katrina's landfall near the Louisiana-Mississippi border, was flooded from surge at the height of the storm. Other large Jackson County neighborhoods such as Porteaux Bay and Gulf Hills were severely damaged with large portions being completely destroyed, and St. Martin was hard hit; Ocean Springs, Moss Point, Gautier, and Escatawpa also suffered major surge damage.

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