Saturday, July 3, 2010
"Hurricanes and Tropical Storms."
A hurricane is a very powerful, sometimes violent storm with strong winds and heavy rains.
A hurricane is a powerful, spiraling storm that begins over a warm sea, near the equator. When a hurricane hits land, it can do great damage through its fierce winds, torrential rains, inland flooding, and huge waves crashing ashore. A powerful hurricane can kill more people and destroy more property than any other natural disaster.
Hurricanes are given a different label, depending on where they occur. If they begin over the North Atlantic Ocean, the Caribbean Sea, the Gulf of Mexico, or the Northeast Pacific Ocean, they are called hurricanes. Like storms that occur in the Northwest Pacific Ocean west of the imaginary International Date Line are called typhoons. Near Australia and in the Indian Ocean, they are referred to as tropical cyclones or tropical storms.
Hurricanes are severe tropical storms that form in the southern Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and in the eastern Pacific Ocean. Hurricanes gather heat and energy through contact with warm ocean waters. Evaporation from the seawater increases their power.
Hurricanes rotate in a counter-clockwise direction around an "eye". Hurricanes have winds at least 74 miles per hour. When they come onto land, the heavy rain, strong winds and heavy waves can damage buildings, trees and cars. The heavy waves are called a storm surge. Storm surges are very dangerous and a major reason why you must stay away from the ocean during a hurricane warning or hurricane.
Scientists have only been studying hurricanes for about 100 years. But there is evidence of hurricanes occurring long in the past. For example, geologists (scientists who study the earth) believe that layers of sediment in a lake in Alabama was brought there by a hurricane in the Gulf of Mexico as long as 3,000 years ago. There is also evidence in Florida of hurricanes more than 1,000 years ago. One of the first human records of hurricanes appears in Mayan hieroglyphics.
Hurricanes are classified into five categories, based on their wind speeds and potential to cause damage.
Category One: Winds 74-95 miles per hour.
Category Two: Winds 96-110 miles per hour.
Category Three: Winds 111-130 miles per hour.
Category Four: Winds 131-155 miles per hour.
Category Five: Winds greater than 155 miles per hour.
In the U.S., the official hurricane season is from June 1 to November 30, but hurricanes can happen any time of the year. Hurricanes are named by the National Weather Service.
Important terms to know:
Hurricane Watch: A hurricane is possible within 36 hours. Stay tuned to the radio and television for more information. The hurricane center is tracking the storm and trying to predict where it may come ashore.
Hurricane Warning: A hurricane is expected withing 24 hours. You may be told to evacuate. You and your family should begin making preparations to evacuate. If your area is having an evacuation, remember to take your Disaster Supply Kit. Do not forget to make plans for your pets if you must evacuate!!
A History of Big Hurricanes.
Hurricane Andrew: This hurricane hit on August 24, 1993 in southern Florida. It then turned and hit Louisiana. More than a million people had to leave the area due to the storm. Heavy rains and tornadoes were part of the hurricane´s destructive power. Until Katrina, Andrew was the most expensive hurricane in the history of the U.S.
Hurricane Floyd: This hurricane, which struck in September 1999, brought so much rain that 13 states were issued federal disaster declarations, more declarations for a single event than ever before. More than $500 million of federal money was spent on helping states recover. North Carolina was hit the hardest of any state.
Hurricane Katrina: This August 2005 storm was the most destructive and costly natural disaster in U.S. history. It produced damage estimated at $75 billion in the New Orleans area and along the Mississippi coast. Katrina was responsible for approximately 1,200 reported deaths, including about 1,000 in Louisiana, 200 in Mississippi, and seven in southern Florida.
Hurricane Rita: The third Category 5 hurricane of the 2005 season, this destructive and deadly storm devastated portions of southeastern Texas and southwestern Louisiana and significantly impacted the Florida Keys.
A tropical storm or tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain.
Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic windstorms such as northeasters, European windstorms, and polar lows, leading to their classification as a "warm core" storm systems.
The term "tropical" refers to both the geographic origin of these systems, which form almost exclusively in tropical regions of the globe, and their formation in maritime tropical air masses. The term "cyclone" refers to such storms´cyclonic nature, with counterclockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere. Depending on its location and strength, a tropical cyclone is referred to by names such as hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, and simply cyclone.
While tropical cyclones or tropical storms can produce extremely powerful winds and torrential rain, they are also able to produce high waves and damaging storm surge as well as spawning tornadoes. They develop over large bodies of warm water, and lose their strength if they move over land. This is why coastal regions can receive significant damage from a tropical cyclone, while inland regions are relatively safe from receiving strong winds. Heavy rains, however, can produce significant flooding inland, and storm surges can produce extensive coastal flooding up to 40 kilometres (25 miles) from the coastline.
Although their effects on human populations can be devastating, tropical cyclones can also relieve drought conditions. They also carry heat and energy away from the tropics and transport it toward temperate latitudes, which makes them an important part of the global atmospheric circulation mechanism. As a result, tropical cyclones or tropical storms help to maintain equilibrium in the Earth´s troposphere, and to maintain a relatively stable and warm temperature worlwide.
Many tropical cyclones or tropical storms develop when the atmospheric conditions around a weak disturbance in the atmosphere are favorable. The background environment is modulated by climatological cycles and patterns such as El Niño-Southern Oscillation. Others form when other types of cyclones acquire tropical characteristics. Tropical systems are then moved by steering winds in the troposphere; if the conditions remain favorable, the tropical disturbance intensifies, and can even develop an "eye". On the other end of the spectrum, if the conditions around the system deteriorate or the tropical cyclone makes landfall, the system weakens and eventually dissipates. It is not possible to artificially induce the dissipation of these systems with current technology.
THANK YOU FOR READING!!