CAUSES OF STROMS AND HURRICANES IN U.S.A

GEOGRAPHICAL LOCATION OF U.S.A:

U.S.A is comprised of 52 states which are surrounded by the Atlantic ,Pacific and the Gulf of Mexico.The lower 50 states are also known as the contiguous United States having the Atlantic Ocean on the East and Pacific Ocean on the West. Canada is in the North of America and Mexico is in the South while The Gulf of Mexico is in the Southeast of U.S.A.

Alaska has the Arctic Ocean on the north and Pacific Ocean on the south.Hawaii is the chain of islands surrounded by Pacific Ocean.

STATES THAT BORDER ATLANTIC OCEAN:

Maine, New Hampshire, Massachusetts, Rhode Island ,Connecticut ,New York, New Jersey, Delaware ,Maryland, Virginia, North Carolina, South Carolina, Georgia, Florida

STATES THAT BORDER THE PACIFIC OCEAN:

Alaska, California, Hawaii, Oregon, Washington

STATES THAT BORDER THE GULF OF MEXICO:

The Gulf of Mexico is one of the largest bodies of water in the world and it is a part of the Atlantic Ocean. Its total area is 1.5 million sq. km.

Alabama, Florida ,Louisiana, Mississippi and Texas

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STORM DEFINATION:A disturbance of the normal condition of the atmosphere, marked by winds of unusual force or direction, along with heavy rain, snow, hail, thunder, and lightning, or flying sand or dust. Ice stroms ,Blizzards ,Tarnadoes ,Tropical cyclones ,Dust evils ,Lake Effect are some of the examples of stroms.

SEVERE WEATHER:In a research paper : “Natural Disasters And Severe Weather” ,The National Weather Service defines severe weather as:Tornadoes ,Hail of greater than 1 inches in diameter and winds of speed greater than 55mph.Borderly speaking, it is defined as weather that can cause intense injuries, deaths and economic loss.1

CAUSES FOR EXTREME WEATHER IN U.S.A.

1. THE CENTRAL PLAINS:

The central plains are a perfect flat passage between the Rockies and the Appalachians creating a straight shot for cold polar air to clash with moist warm air from the gulf

1Knox Pam ,2011:Natural Disaster:What Causes Severe Weather.http://osep.uga.edu/uploads/1/Natural_Disasters_and_Severe_Weather.pdf.Retreived at 4 May 2013

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region. This leads to intense storms as these air masses collide on frontal boundaries in the Plains regions.

2. OTHER COUNTRIES ARE SHIELDED:

Other countries are shielded by mountainous or geographic boundaries on the shorelines which prevent severe storms such as hurricanes from coming ashore easily. And, moist southern air doesn't get the chance to collide with cold polar air to produce severe storms in the first place.

3. THE SIZE OF THE US:

The size of the United States is very large. It covers more than 3.5 million square miles. It is a large target for severe weather.

4. OCEANFRONT PROPERTY:

The shear exposure to the Atlantic and Gulf Coast allows for massive storms that form in the Atlantic to come ashore in coastal regions.

5. OCEAN CURRENTS:

Ocean currents are literally aimed right at the east coast. The North Equatorial Current and Gulf Stream are practically aimed at the United States and cause severe weather.

COMMON TYPES OF STORMS IN U.S.A :

Winter storms ,Floods ,Thunder storms ,Hail storms, Derechostorms ,Tornadoes and Tropical cyclones.

WINTER STORMS:Winter storms derive their energy from the clash of two air masses of different temperatures and moisture levels. Winter storms usually form when an air mass of cold, dry, Canadian air moves south and interacts with a warm, moist air mass moving north from the Gulf of Mexico. The point where these two air masses meet is called a front.

TYPES OF WINTER STORMS IN U.S.A:

Ice storms, Blizzard, Lake effect snow and Nor’easters are common types of winter storms that hit U.S.A .

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a) ICE STORMS:

An ice storm is a type of winter storm caused by freezing rain. The U.S. National Weather Services defines an ice storm as a storm which can accumulate at least 0.25 inches of ice on exposed surfaces.

Ice storms form when a layer of warm air is between two layers of cold air. Frozen precipitation melts while falling into the warm air layer, and then proceeds to refreeze in the cold layer above the ground. This creates freezing rain or a glaze of ice. As the rain

freezes, ice accumulates on roads, tree limbs, power lines, etc., creating dangerous driving conditions and potential power outages.

b) BLIZZARDS:

Blizzard is accompanied by gale-force winds, heavy snow (accumulating at a rate of at least 5 centimeters per hour), and very cold conditions (below approximately -10 degrees Celsius).Blizzards are severe winter storms that combine heavy snowfall, with high winds and freezing temperatures. The combination of cold, wind and snow

They are accompanied by winds that are at least 35 mph or greater. Blizzards also have sufficient falling and/or blowing snow that reduces visibility to 1/4 mile .A severe blizzard is considered to have temperatures near or below 10 degrees Fahrenheit, winds exceeding 45 mph, and visibility reduced by snow to near zero.

C)LAKE EFFCT SNOWLake effect snows occur when a mass of sufficiently cold air moves over a body of warmer water, creating an unstable temperature profile in the atmosphere.

As the cold air flows over the warm lake water, the relatively warm water heats the air's bottom layer as lake moisture evaporates into the cold air. Since warm air is lighter or less dense than cold air, the heated air rises and begins to cool. As the air cools, the moisture that evaporated into it condenses and forms clouds and snow begins falling from the cloud if the air is humid enough. (Graphic Credit: USA TODAY.)

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Cold air moves over warm water and is warmed from below. Moisture evaporates in the air.

Warm moist air rises downwind of lakes and forms heavy snow.

The most likely setting for this localized type of snowfall is when very cold Arctic air rushes over warmer water on the heels of a passing cold front, as often happens in the Great Lakes region during winter. Winds accompanying Arctic air masses generally blow from a west or northwest direction, causing lake effect snow to fall on the east or southeast sides of the lakes.

According to a research paper, “Monitoring and understanding trends in extreme storms”, the frequency of winter and ice storms has become twice since 1960 than preceding 1960.This imposes the great challenge for U.S.A. The dominant factors that determine US winter storms characteristics ( frequency, duration and intensity) are El Nino and La Nina. La Nina favors northerly storms bringing intense snow to Northern Midwest, the northern Rockies, Northern California, while El Nino favors southern storms bringing heavy precipitation to southern states.2Northwest Mexico ,southwest United States including central and southern California experience extreme winters and heavy precipitation due to El Nino phase of the Southern Oscillation.

d) NOR'EASTER

2 Kunkel, Kenneth E., and Coauthors, 2013: Monitoring and Understanding Trends in Extreme Storms: State of

Knowledge. Bull. Amer. Meteor. Soc., 94, 499–514. doi: http://dx.doi.org/10.1175/BAMS-D-11-00262.1 Retrieved at 4 May 2013

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Nor'easters are among winter's most violent storms. A nor'easter gets its name from its continuously strong northeasterly winds blowing in from the ocean ahead of the storm and over coastal areas.

They are strong areas of low pressure that often form either in the Gulf of Mexico or off the East Coast in the Atlantic Ocean.

Nor'easters are notorious for producing heavy snow, rain, and oversized waves that crash onto Atlantic beaches, often causing beach erosion and structural damage. Wind gusts associated with these storms can exceed hurricane force in intensity.

In Alaska, Wind-driven waves from intense storms crossing the Bering Sea produce coastal flooding and can drive large chunks of sea ice inland destroying buildings near the shore. High winds, especially across Alaska's Arctic coast, can combine with loose snow to produce a blinding blizzard and wind chill temperatures to 90F below zero. Extreme cold (-40F to -60F) and ice fog may last a week at a time. Heavy snow can impact the interior and is common along the southern coast. With only brief glimpses of the winter sun across the southern horizon, the snow accumulates through the winter months. In the mountains, it builds glaciers, but the heavy snow accumulations can also cause avalanches or collapse roofs of buildings. A quick thaw means certain flooding. Ice jams on rivers can also cause substantial flooding.

FLOODS:

Floods are characteristically the result of heavy precipitation that causes much increase in water level of reservoirs than their storage capacity. Flash floods driven by quick and violent bursts of rain can flood homes, basements and businesses causing serious damage to infrastructures and property. Flooding is a very dangerous storm phenomenon that results in frequent deaths and widespread property damage each year.

TORNADOES:

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Tornadoes are more mutual in the United States than in any other country. The United States receives more than 1,200 tornadoes annually—four times the quantity seen in Europe.

Most tornadoes in the United States follow east of the Rocky Mountains.( also called twisters.) The Great Plains, the Midwest, the Mississippi Valley and the southern United States are all areas that are vulnerable to tornadoes. They are comparatively rare west of the Rockies and are also less normal in the northeastern states.

Tornado Alley is a colloquial term for an area mostly likely to to (sometimes violent) tornadoes. There is no officially defined 'Tornado Alley' - at its broadest this area spreads from Texas to Canada with its core centered on Oklahoma, Kansas and northern Texas. Another highly significant region - colloquially known as Dixie Alley - is the southern United States and particularly the northern and central parts of Alabama and Mississippi. Florida is one of the most tornado prone states. However, Florida tornadoes only rarely line of attack the strength of those which can occur elsewhere.

Although positive conditions for tornadoes in the United States can occur at any time, they are most common in spring and least common in winter. Because spring is a temporary period for the climate, there are more chances of cooler air meeting with warmer air, resulting in more thunderstorms. Tornadoes can also be produced by falling tropical, which usually occur in late summer and autumn. In the United States, thunderstorms accomplished of producing tornadoes usually form when the temperature is at its highest, typically from 4:00 p.m. to 7:00 p.m.

Although the period in which most tornadoes attack ("tornado season") is March through August, tornadoes - including violent tornadoes and major tornado occurrences - have been documented in the United States during every month of the year. Two examples of this are when a series of tornadoes hit the state of Indiana on November 22, 1992, and injured at least nine people. Another important non-season tornado was on December 9, 1991, where a tornado hit the area of McLean County, Illinois.

Usually, tornadoes hit definite areas of the United States in specific seasons. During the winter months, tornadoes are usually covered in the Southern area of the country, as well as states near the Gulf of Mexico. This is due to cold air moving southward reaching its southern limit of increase, and stopping over the Gulf Coast. As spring comes, hot air gradually moves back into the Gulf Coast, causing the mass of colder air to be pressed forward and out of the Gulf States and into the Southeastern states, where the frequency for tornadoes is the most during the month of April.

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Tornadoes have been accepted in every U.S. state (not including the non-state territories of Guam, the Virgin Islands, American Samoa, and Puerto Rico) at least once since 1950, although some positions and states are hit by tornadoes extreme more than others. For example, the average number of tornadoes to smash the states of Alaska, Rhode Island, and Vermont is fewer than one, while the state of Oklahoma accepts an average of 52 tornadoes per year, and the state of Texas is hit with 126 tornadoes in an ordinary year. The state which has the maximum number of tornadoes per unit area is Florida. A number of Florida's tornadoes occur along the edge of hurricanes that attack the state. The state with the maximum number of strong tornadoes per unit area is Oklahoma. States such as Oklahoma and Kansas have much lower population masses than Florida, so tornadoes may go unreported.

Impacts

Injuries and fatalities

The United States receives over 80 deaths and 1,500 injuries related with tornadoes each year. According to the National Oceanic Atmospheric Administration, most tornado deaths are initiated by people not following guidelines on what to do the right way. They also comment that some people are not even notified that a tornadic storm is coming, while others get a warning but do not believe that a tornado will hit their area. In 2007, the year that data was last presented, 81 people were killed by tornadoes in the United States. Florida was the state with the most losses, having 21. Florida was followed by Kansas (14), Alabama (10), Georgia (10), Texas (9), Missouri, Louisiana, and Michigan (3), and six other states with any one or two deaths.

Tropical Cyclones:

Low pressure structures that form over warm tropical waters and have gale force winds (constant winds of 63 km/h or greater and gusts in excess of 90 km/h) near the centre. Precisely they are strong as a non-frontal low pressure system of synoptic scale evolving over warm waters having controlled convection and a maximum mean wind speed of 34 knots or greater ranging more than half-way around near the centre and persevering for at least six hours.

Heavy rainfall connected with the passage of a tropical cyclone can create extensive flooding. This can cause further harm and death by drowning. The heavy rain can continue as the cyclone moves inland and decays, hence flooding due to a perished cyclone can occur a long way from the tropical coast as the remains of a cyclone move into central and southern parts of the continent.

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Tropical cyclones are one of the most hazardous natural hazards to people. Every year, they cause significant loss of life and do massive damage to property. However, tropical cyclones are important features of the Earth's atmosphere, as they transfer heat and energy between the equator and the cooler regions nearer the poles.

How do tropical cyclones form?

In the tropics there is a broad region of low pressure which expanses either side of the equator. The winds on the north side of this zone blow from the north-east (the north-east trades) and on the southern side blow from the south-east (south-east trades).

Within this region of low pressure the air is heated over the warm tropical ocean. This air rises in distinct parcels, causing thundery showers to form. These showers usually come and go, but from time to time, they group together into large masses of thunderstorms. This creates a flow of very warm, moist, rapidly rising air, leading to the increase of a centre of low pressure, or depression, at the surface.

There are several trigger mechanisms required to change these cloud masses into a tropical cyclone. These trigger mechanisms depend on numerous conditions being 'right' at the same time. The most significant factors are:

1. a source of warm, moist air consequent from tropical oceans with sea surface temperatures normally in the area of, or in excess, of 27 °C;

2. winds near the ocean surface blowing from different directions joining and causing air to rise and storm clouds to form;

3. Winds which do not vary greatly with height - known as low wind shear. This allows the storm clouds to rise upright to high levels;

4. Enough distance from the equator to provide spin or turn.

Tropical cyclone warnings:

The USA has the most refined tropical cyclone warning system. Once a tropical depression has been recognized, a series of forecast advisories, which detail the estimated track and likely strength of the tropical cyclone, are broadcast. When there are definite warnings that a tropical cyclone is approaching land, watches and warnings along coastal areas are raised, which aim to give information to the local experts of places likely to be in the tropical cyclone's path, so that they can make planning to protect public safety.

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Particularly designed shelters in which people can drive out the worst of the weather may have been built in progress. Coastal regions nearly in a tropical cyclone's path are mostly dangerous and people are usually advised to move away from these. In the USA, this can involve the mass removal of a million or more people. Warnings are broadcast on TV and radio. NOAA Weather radio is available on a diversity of frequencies and gives up-to-date information and advice. There is also a lot of information on a variety of web sites, the most powerful being those conserved by NOAA and the National Hurricane Center.

More from NOAA's FAQ on tropical cyclone warnings

Met Office Tropical Cyclones

Tropical Cyclone Frequently Asked Questions

Notable tropical cyclones:

Katrina - 2005 - Katrina was the most costly hurricane on record causing an estimated $75 billion in damage in Louisiana and Mississippi

Andrew - 1992 - Andrew was a Category 5 hurricane which hit south-east Florida and south-east Louisiana causing $44,878 million of damage

The most deadly tropical cyclone ever recorded hit Bangladesh in 1970 killing approximately 300,000 people as a result of the storm surge

More from NOAA's FAQ on tropical cyclone records

Is climate change affecting tropical cyclones?

The impact of climate change - precisely global warming produced by the burning of fossil fuels - on tropical cyclone activity is the subject of continuing debate and research in the scientific community. Recent catastrophic events, such as Hurricane Katrina, have given the debate a higher summary. While some evidence has been presented in order to show a recent upturn in tropical cyclone activity in some parts of the world, others have claimed that natural variations in tropical cyclone activity - on a regional, annual and inter-decadal scale - mask any signal from the impact of global warming, which remains comparatively small.

Although there is no clear accord on whether global warming is currently having any measurable control on tropical cyclones, climate models show that there may be an increase in tropical cyclone intensity in the future, under nonstop global warming. However, the models also indicate that tropical cyclone rate will either remain unmoved or decrease.

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A number of tropical cyclone scientists came together in 2006 to issue a statement on the rank of understanding and inquiry into tropical cyclones and climate change, which was offered to the World Meteorological Organization.

WMO statement on tropical cyclones and climate change.

Nature Geoscience article on tropical cyclones and climate change.

THUNDERSTORMS:

A thunderstorm is a kind of storm that generates lightning and thunder. It is usually accompanied by heavy precipitation. Thunderstorms arise throughout the world, with the maximum frequency in tropicalrainforest regions where there are situation of high humidity and temperature along with atmospheric change.

Thunderstorms can create many types of damage weather such as lightning, hail, tornadoes, straight-line winds, flooding and more. The biggest contributors to damaged property are likely hail and wind, which can cause many types of external property damage. Given the presence of an abundance of heat, moisture, volatility, and lifting mechanisms daily, thunderstorms are most familiar in Florida.

Thunderstorms are the consequence of moist, warm air going up and condensing as it cools at higher altitudes, forming cumulonimbus clouds. Thunderstorms usually occur in mid-latitudes from Spring through Fall, with the most strong storm activity often taking place in the summer months in many locations.

Thunderstorms come in many forms. Dry thunderstorms, or those that do not precipitate, often cause wildfires from lightning strikes in places like Colorado. The biggest type of storm cell, a supercell, produces many hazardous weather conditions, together with hail more than 4 inches in diameter and tornadoes. States like Kansas and Oklahoma, for instance, are frequently a fatality of supercell storms that cause wide damage every year.

HAILSTORMS:

Hail storms are defined as thunderstorms that make hail. Hail is defined as opening at a diameter of 0.2 inches or more. Hail can raise as big as golf balls, baseballs, and even soccer balls. Hail bigger than 0.75 inches is considered large enough to cause severe damage in the United States. According to NOAA, hailstones can go down at speeds up to 120 mph.

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In the United States, hails most commonly occur in Hail Alley: The enormous Plains states, particularly northeastern Colorado and southeastern Wyoming, obtain more hail yearly than any additional part of the United States. The states experiencing the most common hail include: Colorado, Wyoming, Nebraska, Kansas, Texas, and Oklahoma. The major hailstone yet recorded in the United States was 8 inches in diameter, weighing almost two pounds.This hailstone was improved in Vivian, SD on July 23, 2010.

DERECHO STORMS:

A derecho is a huge, violent, fast-moving, complex of thunderstorms that chase one another along a course of at least 240 miles, with wind gusts of at slightest 58 mph.

One of the most new important derechos to crash the United States takes place on May 8, 2009. This climate phenomena traveled further than a thousand miles in 24 hours from southeastern Kansas to the southern back of the Appalachian Mountains.

Forty-five tornadoes were sighted in this tedious storm. Winds in the strongest derechos can top 100 mph.

HURRICANES:A hurricane is a tropical cyclone with winds that have speed of 74 miles per hour or more.These are called different names depending upon where they form. Those that form over Atlantic Ocean are called hurricanes. If they form over Northwest Pacific Ocean are called typhoons. In South pacific and Indian Ocean they are called cyclones. The scientific name is same all over the world tropical cyclone.

FORMATION:

CONDITIONS FOR HURRICANES FORMATION

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Warm moist air, warm water, high temperature, humidity are the conditions that make hurricanes. There must be layer of warm air at the top of sea with temperature of 80 degrees F (26.5 degrees C) to form hurricanes. Hurricanes start when warm, moist air from the surface of ocean rise rapidly into the atmosphere, where it encounters cooler air that causes the warm moist air to condense and form clouds with drops of rain. This condensation releases latent heat and that latent heat further warms the cool air below causing it to rise and make way for more warm air to rise from ocean surface.

As this cycle continues so more warm air enters into developing hurricane and more heat is transferred from the surface of ocean to the atmosphere. This heat exchange creates a wind pattern that spirals around eye of hurricane.

CONVERGING WINDS CREATE HURRICANESConverging winds are the winds moving in different directions that run into each other at a certain spot. These winds that converge near the surface of water collide and push more water vapors in the upward direction, increasing the circulation of warm moist air and accelerating the speed of wind. At the same time strong winds circulating at higher altitudes push the rising warm air away from the center of hurricane and send it to the spinning hurricane pattern of bands.High pressure at high altitudes usually above 30.000 feet (9,000 meters),also pull heat away from the center of hurricane and result in cooling of rising warm moist air. As high pressure air moves toward low pressure center of hurricanes it result increase in speed of winds.Hurricanes cannot be formed until winds have sufficient distance from the equator for the Coriolis force to be significant, usually at least 483km because at equator there is no spin of earth. Hurricanes winds in the northern hemisphere circulate in a counterclockwise direction around hurricane eye while hurricane winds in the southern hemisphere circulate clockwise.

STRUCTRE OF HURRICANES:A hurricane is complicated structure

which consists of three main parts; Inner eye, Eye wall and Outer rain bands.EYEThe eye is the hole at center portion of hurricane. It is the calmest, low pressureplace in hurricane as conditions are clear with less warm air, less wind speed of 15mph.The eye is typically 20 to 40 miles however they also know to be very small just few miles and sometimes greater than 40 miles. The eye does not usually forms until winds have speed

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of 74 mph (hurricane strength) and thus its formation is good indicator of strong and organized hurricane.EYE WALL:The eye wall surrounds the eye of hurricane. The strongest winds and heaviest rains are found in eye wall, making it the most dangerous part of the hurricane. Contraction and expansion of eye wall can cause changes in the wind speed and hurricane strength. As hurricanes grow and changes they can build concentric eye walls that replace the original eye wall. Changes in the eye wall size and eye wall replacement result in causing challenges in forecasting the strength of hurricane.RAIN BANDS:Rain bands are long curving bands of clouds and thunderstorms that spiral out from eye wall. Usually heavy rain and wind are associated with rain bands. These rain bands form outermost borders of hurricanes and the speed of winds contained within the rain bands decreases outward from the eye wall. The gaps between rain bands are calm having no wind or rain. (Dan Stillman, Institute for Global Environmental Strategies).

SAFFIR- SIMPSON HURRICANE WIND SCALE

The saffir-simpson Hurricane wind scale is a 1 to 5 rating based on a hurricane’s sustained wind speed. This scale estimates potential property damage. Hurricanes reaching category 3 and higher are considered major hurricanes because of their potential for significant loss of life and damage. Category 1 and 2 stroms are still dangerous, however, and require preventative measures.

Category Sustained winds Types of damage due to hurricane winds1 74-95 mph

119-153 km/hVery dangerous wind will produce some damage: well constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of tree will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles will likely result in power outages that

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could last a few to several days2 96-110 mph

154-177 km/hExtremely dangerous wind will cause extensive damage: well-constructed frame home could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near total power loss is expected with outages that could last from several days to weeks

3(major)

111-129 mph178-28 km/h

Devastating damage will occur: well-built framed homes may incur major damage or removal of roof decking and gable end. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to week after the storm passes

4(major)

130-156 mph29-251 km/h

Catastrophic damage will occur: well built frame homes will sustain severe damage with loss of most of roof structure and/ or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Power poles and fallen trees will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months

5(major)

157 mph or higher252 km/h or higher

Catastrophic damage will occur: a high percentage of frame houses will be destroyed, with total roof failure and wall collapse. Fallen trees and power pole will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabited for weeks or months.

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CAUSES OF KATRINA AND SANDY HURRICANES

Katrina was a tropical cyclone, with a compact symmetrical wind field that whipped around a circular low pressure center. Like most tropical cyclones, Katrina was a warm-core storm that drew its energy from warm waters of the tropical Atlantic Ocean. Sandy has similar characteristics while it was blowing through the tropics. But as the storm moved northward, it merged with the weather system arriving from the west and started transitioning into an extra tropical cyclone.The name sound similar, but there are fundamental differences between the two types of storms. While tropical cyclone are fueled by sharp temperature contrasts between masses of warm and cool air. Extra tropical cyclones tends to be asymmetric, with broad wind and cloud field shaped more like commas than circles. So when tropical cyclones become extra tropical, their wind and cloud fields expand dramatically. Their strongest65 kilometer per hour stretches about 500 kilometer (300 miles) from edge to edge. For sandy, wind of that intense winds generally weaken during this process , but occasionally a transitioning storm retain hurricane force winds, as was the case with sandy. The most

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noticeable difference is the extend of strong wind fields. For Katrina, winds over sity stretches 1,500 kilometers (900 miles). “Katrina wind were more intense, but they covered less area,” said Brian McNoldy, a university of Miami meteorologist who authored a washington post article explaining why sandy’s storm surge caused so much damage. “when that boils down to storm surge, Katrina was capable of generating a locally higher surge, but sandy was capable of generating destructive surge over a larger length of coastline.Reference: Data courtesy of the Jet Propulsion Laboratory's QuikSCAT and the Indian Space Research Organization OceanSat-2 missions. Jenni Evans, Bryan Stiles, Brian McNoldy, and Alexander Fore contributed to this feature.

NAMING OF HURRICANES

History of hurricanes name: for several hundred years many hurricanes in the west Indies were named after the particular saint’s day on which the hurricanes occurred e.g. “Hurricane santa Ana”. The used of women name for the storm was in the novel “storm” by George R. Stewart , published by random House in 1941, and since filmed by Walt Disney. The practice of naming hurricanes solely after women came to an end in 1978 when men’s and women’s named included in the Eastern North Pacific storm lists. In 1979, male and female names were included in the lists for the Atlantic and Gulf of Mexico. (U.S. DEPARTMENT OF COMMERCE NOAA, national weather service).There are actually six lists of names in use for storm in the Atlantic. These lists rotate. One each year; the list of this year’s names will not be reused for six years. The name get recycle each time the list came up., with one exception : storms so devastating that reusing the name is inappropriate. In this case , the name is taken of the list and another name is used to replaced it; there will not be another hurricane Andrew, because Andrew has been replaced by Alex on the list. List of hurricane names for 2013 : Andrea, Barry, Chantal, Dorian, Erin, Fernand, Rebekah, Sebastien, Tanya, Van, wendy.

CAUSES OF HURRICANES:Hurricanes need heat and moisture to form. They generally are born over warm, Tropical Ocean, where those conditions exist. Global warming increases because of human activities, which leads to the increase in air and water temperature over the world, which mark easier for hurricanes to form and gain damaging force.Scientist believe that the natural salinity and variation in temperature in the Atlantic increase the severity of hurricanes over the previous years, which is the part of natural environmental cycle that shifts back and forth every 40 to 60 years.

Frequency and severity of Hurricanes increases: Three main factor that contribute in the formation of hurricanes are

Rise in temperature of air and water over the globe.

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Human activities like deforestation and greenhouse gases release through industrial and agricultural processes leads to the rise of temperature frequently nowadays than the past years.

Failure to take action now to lower atmospheric level of greenhouse gases will responsible for frequent and sever hurricanes in coming years.

Research Report:The research of scientist at Princeton University and the Massachusetts institute of technology provide an indication that climate change could cause extraordinary hurricanes to strike the New York City and other coastal area in coming hundred years.The professor of geosciences at Princeton University, Mr. Michael Oppenheimer says, “sea level rise and warmer water temperature could possibly cause a storm that likes of which have not been seen”.Scientist believe that the rise of sea level of one meter by 2100, which increase the frequency, so called “storm of the century”, If rise of sea level is not stopped so such a storms occurs closer to every 10 years.By the evidence of research, “change in climate will increase amount of storms and size simultaneously, causing in a significant rise of storm surge”.There is much evidence which support the facts that hurricanes will increase their intensity and become frequent. The American metrological association wrote in 2007 report that growing bodies of scientific work suggest that hurricanes become more intense over the several last decades. According to report of NASA, there is increase in temperature of 1 Fahrenheit over the past 100 years on the surface of tropical oceans.The greenhouse gases increase in temperature of sea surface in hurricanes formation region. Over the last 50 years it is notice that there is strong relationship between the tropical Atlantic sea surface temperature and Atlantic hurricanes activities by the power dissipation index i.e. storms intensity, duration and frequency. This evidence show that this increase in hurricane activities cause by the contribution of human activities. However, a confident calculation of human impact on hurricanes need further studies by models and observation, with emphasis on distinguishing natural from human-induced changes in hurricanes activity through their influence on factor such as historical sea surface temperature, wind shear, and atmospheric vertical stability.The wind speed of hurricanes/typhoon and rainfall rate will increases by human cause warming activities. The studies of model simulation propose that for each 1oc increase in tropical sea surface temperature, hurricanes surface wind speeds will increase by 1 to 8% and core rainfall rates 6 to 18%.

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Atlantic Ocean AND United state:

The most Atlantic hurricanes start from the west coast of Africa and move west toward United States. Hurricanes are the regular feature of north Atlantic basin during late summer and earlier autumns. Atlantic hurricanes form, move, die over the large part of tropical and sub-tropical water of Atlantic basin. The hurricane season in Atlantic is June to November. The number of hurricanes occurring in any given season is referred to as the seasonal abundance or frequency. The term “seasonal activity” is often used interchangeably with the term season abundance or seasonal frequency. The abundance hurricanes is determined by the prevalence of necessary environmental condition for tropical cyclones development and intensification. However, since every hurricane develops from a tropical storm, which in turn comes from depression or some other disturbance, the abundance of hurricanes is also function of frequency and vitality of pre-hurricanes disturbance.The United States hurricane base ho combination of wind, central pressure and storm surge.The continued coastal growth and inflation will almost certainly result in every major landfilling hurricanes.

Difference in East and West coast of USA:In both basin of Atlantic Ocean hurricanes form (i.e. the Atlantic ocean, Gulf of Mexico and Caribbean sea) which cover the east side of U.S. continental and northeast pacific basin to the west of the U.S. U.S is never hit by northeast pacific but U.S mainland hit by Atlantic basin less than twice a year. For this there is two reasons.

1) The hurricanes form in the tropical and subtropical latitude when they move toward the west-northwest. In the Atlantic the hurricanes strike to the U.S east coast area because of motion. And the west-northwest path take those hurricanes farther off-shore, away from the U.S west cost, in the northeast pacific.

2) Secondly, the major factor which is involve is the temperature difference in east and west coasts of U.S. The east coast provide the source of warm water (>80of or 26.5oc) which help in maintaining hurricanes. In the middle of summer the oceanic temperature of west coast of U.S. is above the lower 70s. This

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temperature is comparatively lower which is not energetic to sustain the hurricanes strength. This cooler water decrease the strength of storm when hurricanes of northeast pacific move back toward the U.S west coast.The formation of hurricanes is also affected because of ocean clockwise current. The current move from north to south in the pacific, whereas on the east coast the warm water move from south to north from the Gulf flows.

In the Pacific Ocean, the current of north pacific flow from japan eastward across the pacific then split in northern flowing Alaska current and southern flowing current of California. The cool-water of California sweep down the west coast of United States, act as hurricanes repellant, protecting California and northern Baja California from hurricanes.Upper level wind play an important role which carry storm and move it away from the California. These are the northwest winds, which push warmer water offshore and drawing cooler waters up to the surface which weaken the storms nature that did approach a California.

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REFRENCES:

Atlantic Ocean and USA. http://usatoday30.usatoday.com/weather/resources/askjack/wfaqhurw.htm.Retrieved at 4 May 2013.

Causes of Katrina and Sandy. http://www.nasa.gov/mission_pages/hurricanes/archives/2012/h2012_Sandy.html.Retrived at 3 May 2013

Climate Change Cause Hurricanes; U.S.A NEWS. http://www.usnews.com/news/articles/2012/02/24/climate-change-could-cause-killer-hurricanes-in-nyc. Retrieved at 4 may 2013.

Deadly Storms in U.S.A. http://www.accuweather.com/en/weather-news/deadly-super-derecho-strikes- m/67383.Retrived at 3 May 2013

Five Factors Contribute To Increased Severe Weather in U.S.A. http://weather.about.com/od/severestorms/tp/top5severeUS.htm.Retrieved at 29 April 2013

Geographical Location of U.S.A. http://www.mapsofworld.com/usa/.Retrieved at 30 April 2013.

Geography Of Gulf Of Mexico http://geography.about.com/od/unitedstatesofamerica/tp/gulfstates.htm.Retrieved at 1May 2013

Hurricanes in east and west coast of USA http://www.jpl.nasa.gov/news/news.php?release=2012-329.Retrieved at 4 May 2013.

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Hurricanes Basics. http://www.knowitall.org/nasa/simulations/weather/hurricane.html.Retrived at 2 May 2013.

Hurricanes Formation. http://www.nasa.gov/audience/forstudents/k-4/stories/what-are-hurricanes-k4.html.Retrived at 3 May 2013.

Ice storm and Lake Effect Snow. http://www.weatherwizkids.com/weather-winter-storms.htm.Retrieved at 2 May 2013

Knox Pam, 2011: Natural Disaster: What Causes Severe Weather. http://osep.uga.edu/uploads/1/Natural_Disasters_and_Severe_Weather.pdf.Retrieved at 4 May 2013

Kunkel, Kenneth E., and Coauthors, 2013: Monitoring and Understanding Trends in Extreme Storms: State of Knowledge. Bull. Amer. Meteor. Soc., 94, 499–514. http://dx.doi.org/10.1175/BAMS-D-11-00262.1 Retrieved at 4 May 2013.

Naming of Hurricanes. http://www.aoml.noaa.gov/general/lib/reason.html.Retrieved at 3 May 2013.

SAFFIR-SIMPSON Hurricane Scale. http://www.nhc.noaa.gov/aboutsshws.php.Retrieved at 3 May 2013.

Storm Definition. http://dictionary.reference.com/browse/storm.Retrieved at 29 April 2013

Structure of Hurricanes. http://www.nc-climate. ncsu.edu/climate/hurricanes/structure.php. Retrieved at 2 May 2013.

The Hurricane Research Division (HRD) is a part of the Atlantic Oceanographic and Meteorological Laboratory (AOML). http://www.aoml.noaa.gov/hrd/tcfaq/G8.html. Retrieved at 4 May 2013.

Tornadoes and Tropical cyclone formation in U.S.A http://www.britannica.com/EBchecked/topic/606551/tropical-cyclone/247926/Tornadoes.Retrieved at 2May 2013

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U.S.A States That Surround Atlantic Ocean http://wiki.answers.com/Q/What_state_is_the_Atlantic_ocean_near.Retrieved at 30 April 2013

Winter storms.http://www.weather.com/encyclopedia/winter/types.html.Retrieved at 1May 2013

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