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Cedar Key, Florida

Cedar Key, Florida

Cedar Key is a city located in Levy County, Florida. As of the 2000 census, the city had a total population of 790.

History

Founded in 1842 as a resort for wealthy planters, Cedar Key became a center for pencil manufacturing when the Eberhard Faber Pencil Company bought huge tracts of land, for 50 cents per acre ($124/km²), in 1855. The town was originally located on an outer island locally known as Atsena Otie, but was rebuilt on a more protected island after a terrible hurricane struck at approximately 4 a.m. September 29, 1896. Today there are a few remnants of the original town on Atsena Otie, including stone water cisterns, and a graveyard whose headstones conspicuously date from only before 1896. There are also many of the juniper (Juniperus virginiana subsp. silicicola) trees that originally drew the pencil company. These were misidentified as cedars by early settlers, whence the name 'Cedar Key'. The old-fashioned fishing village is now a tourist center with several regionally famous seafood restaurants. The village holds two festivals a year, the Spring Sidewalk Art Festival and the Fall Seafood Festival, that each attract thousands of visitors to the area. After a statewide ban on large scale net fishing went into effect July 1, 1995 a government retraining program helped many local fishmen begin farming clams in the muddy waters. Today Cedar Key's clam-based aquaculture is a multi-million dollar industry. A local museum exhibit displays a reproduction of one of the first air conditioning installations. The system, with compressor and fans, was created in Cedar Key to ease the lot of malaria patients. It is certainly hot and humid in the summer.

Geography

malaria Cedar Key is located at (29.145558, -83.041544). According to the United States Census Bureau, the city has a total area of 5.3 km² (2.0 mi²). 2.4 km² (0.9 mi²) of it is land and 2.9 km² (1.1 mi²) of it is water. The total area is 55.39% water.

Demographics

As of the census of 2000, there are 790 people, 411 households, and 244 families residing in the city. The population density is 335.2/km² (864.7/mi²). There are 686 housing units at an average density of 291.1/km² (750.9/mi²). The racial makeup of the city is 97.47% White, 0.13% African American, 0.63% Native American, 0.25% Asian, 0.00% Pacific Islander, 0.51% from other races, and 1.01% from two or more races. 1.52% of the population are Hispanic or Latino of any race. There are 411 households out of which 14.4% have children under the age of 18 living with them, 48.7% are married couples living together, 8.3% have a female householder with no husband present, and 40.4% are non-families. 34.8% of all households are made up of individuals and 14.8% have someone living alone who is 65 years of age or older. The average household size is 1.92 and the average family size is 2.42. In the city the population is spread out with 13.2% under the age of 18, 4.8% from 18 to 24, 15.6% from 25 to 44, 40.1% from 45 to 64, and 26.3% who are 65 years of age or older. The median age is 54 years. For every 100 females there are 91.7 males. For every 100 females age 18 and over, there are 92.2 males. The median income for a household in the city is $32,232, and the median income for a family is $41,190. Males have a median income of $27,375 versus $31,806 for females. The per capita income for the city is $22,568. 11.1% of the population and 6.6% of families are below the poverty line. Out of the total population, 10.5% of those under the age of 18 and 9.9% of those 65 and older are living below the poverty line.

External links


- [http://www.cedarkey.org/ Cedar Key Chamber of Commerce] Category:Cities in Florida Category:Levy County, Florida

2000

This article is about the year 2000. For other uses of 2000, see 2000 (number) or 2000 (breakdancing move). 2000 (MM) is a leap year starting on Saturday of the Gregorian calendar. Popular culture also holds the year 2000 as the first year of the 21st century and the 3rd millennium. By strict interpretation of the Gregorian Calendar, however, this distinction falls to the year 2001. This is due to the fact that the first century began with the year 1, and there does not exist a year zero. The first century (or first 100 years AD) was from January 1, in the year one (1 AD) through December 31, in the year one-hundred (100 AD). The second century began on January 1, in the year one-hundred and one (101 AD). The year 2000 is also marked as:
- The International Year for a Culture of Peace.
- The World Mathematical Year. See also Wikipedia's almanac of events for this year.

Events

January


- January 1 - Millennium celebrations take place throughout the world. Y2K passes without the serious, widespread computer failures and malfunctions that had been predicted.
- January 5-January 8 - The 2000 al-Qaida Summit
- January 6 - The last remaining Pyrenean Ibex is found dead.
- January 10 - America On-line announces an agreement to buy Time Warner for $162 billion. This is the largest-ever corporate merger.
- January 11 - the armed wing of Islamic Salvation Front concludes its negotiations with the government for an amnesty and disbands in Algeria.
- January 11 - The trawler Solway Harvester sinks off the Isle of Man.
- January 14 - A United Nations tribunal sentences five Bosnian Croats up to 25 years for the 1993 killing of over 100 Bosnian Muslims in a Bosnian village.
- January 16 - In Sacramento, California a commercial truck carrying evaporated milk is driven into the state capitol building killing the driver.
- January 24 - God's Army, Karen militia group led by twins Johnny and Luther Htoo, take 700 hostages at a Thai hospital near the Burmese border.
- January 30 - St. Louis Rams 23 defeat the Tennessee Titans 16 to win the Super_Bowl_XXXIV
- January 30 - Off the coast of Côte d'Ivoire, Kenya Airways Flight 431 crashes into the Atlantic Ocean, killing 169. Within a day, Alaska Airlines Flight 261 crashes off the California coast into the Pacific Ocean, killing 88.
- January 31 - Dr. Harold Shipman in sentenced to life in prison for murder of at least 15 of his patients out of 365 suspected victims.

February


- February 4 - German extortionist Klaus-Peter Sabotta is jailed for life for attempted murder and extortion in connection with sabotage of German railway lines.
- February 6 - Tarja Halonen is elected the first Finnish female president.
- February 13 - Final original Peanuts comic strip is published.
- February 14 - The spacecraft NEAR Shoemaker entered orbit around asteroid 433 Eros, the first spacecraft to orbit an asteroid.

March


- March 1 - The Constitution of Finland is rewritten.
- March 2 - Hans Blix assumes the position of Executive Chairman of UNMOVIC.
- March 8 - Tokyo train disaster.
- March 9 - FBI arrests suspected purveyor of art forgeries, Ely Sakhai, in New York City.
- March 10 - The NASDAQ Composite Index reaches an all-time high of 5048. ([http://dynamic.nasdaq.com/dynamic/IndexChart.asp?symbol=IXIC&desc=NASDAQ+Composite&sec=nasdaq&site=nasdaq&months=84])
- March 18 - 2000 Taiwanese presidential election: Chen Shui-bian is elected President of the Republic of China (Taiwan).
- March 20 - Jamil Abdullah Al-Amin, a former Black Panther, is captured after gun battle that left a sheriff's deputy dead.
- March 21 - Pope John Paul II began the first office visit by a Roman Catholic pontiff to Israel.
- March 21 - US Supreme Court ruled the goverment lacked authority to regulate tobacco as an addictive drug, throwing out the Clinton administration's main anti-smoking initiative.
- March 26 - Presidential elections in Russia: Vladimir Putin elected President.
- March 30 - America's Cup 2000 retained by Team New Zealand near Auckland. Prada Challenge 2000 lost 0-5 in a "best-of-9".

April

April.]]
- April 1 - Japanese prime minister Keizo Obuchi suffers a stroke and falls into a coma.
- April 3 - United States v. Microsoft: Microsoft is ruled to have violated United States antitrust laws by keeping "an oppressive thumb" on its competitors.
- April 5 - Yoshiro Mori replaces Obuchi as prime minister of Japan.
- April 7 - Attack submarine ex-Trepang completes being recycled.
- April 16 - Tuanku Syed Putra ibni Almarhum Syed Hassan Jamalullail, Raja of Perlis dies after a reign of 55 years. He was the longest reigning monarch in the world since the death of Prince Franz Joseph II of Liechtenstein.
- April 17 - Tuanku Syed Sirajuddin becomes Raja of Perlis.
- April 22 - In a predawn raid, federal agents seize six-year old Elián González from his relatives' home in Miami, Florida and fly him to his Cuban father in Washington, DC ending one of the most publicized custody battles in US history.
- April 25 - The State of Vermont passes HB847, legalizing Civil Unions for same-sex couples.

May


- May 3 - A rare conjunction occurs on the New Moon including all seven of the traditional celestial bodies known from ancient times up until 1781 with the discovery of Uranus. The May 2000 conjunction consisted of: the Sun and Moon, Mercury, Venus, Mars, Jupiter, and Saturn.
- May 3 - Computer pioneer Datapoint Corporation files for Chapter 11 bankruptcy.
- May 12 - The Tate Modern opens in London.
- May 13 - In Enschede a heavy fireworks explosion kills 20 and leaves an entire neighborhood in ruins.
- May 18 - Boo.com collapses due to lack of funds after six months.
- May 25 - Israel withdraws IDF troops from southern Lebanon after 22 years.
- May 28 - The volcano Mount Cameroon erupts.

June


- June 1 - Mark Mendlan, professional wrestler known by his ring name "Kid Gorgeous," is killed while wrestling at a show in New Hampshire.
- June 7 - U.S. District Judge Thomas Penfield Jackson of the 4th circuit ordered the breakup of Microsoft Corp.
- June 10 - The New Jersey Devils defeat the Dallas Stars 4 games to 2 to win the 2000 Stanley Cup Finals.
- June 10 - The 2000 European Football Championship begins, hosted jointly by Belgium and the Netherlands.
- June 21 - Section 28, a law preventing the promotion of homosexuality is repealed by the Scottish Parliament.
- June 23 - Palace Backpackers Hostel fire in Childers, Queensland, Australia, kills 15 people.
- June 30 - During a set of the band Pearl Jam at the Roskilde Festival near Copenhagen, 9 die and 26 are injured in the crowd.

July

July
- July 2 - France beat Italy 2-1 to win the 2000 European Football Championship with a golden goal.
- July 2 - Presidential election of Mexico. Vicente Fox wins the Presidency as candidate of the rightist PAN (National Action Party).
- July 10 - In southern Nigeria, a leaking petroleum pipeline explodes killing about 250 villagers who were scavenging gasoline
- July 10 - Death of Denis O Conor Donn, died 10th July 2000, aged 88; succeded by his son, Desmond as The O Connor Donn
- July 18 - Alex Salmond resigns as the leader of the Scottish National Party
- July 25 - A Concorde carrying Air France Flight 4590 crashes just after takeoff from Paris killing all 109 aboard and 5 on the ground.

August


- August 1 - The Santa Cruz Operation announced that it will sell its Server Software and Services Divisions, as well as UnixWare and OpenServer technologies, to Caldera Systems,Inc.
- August 8 - Confederate submarine H.L. Hunley is raised to the surface after 136 years on the ocean floor.
- August 12 - The Russian submarine Kursk sinks in the Barents Sea, resulting in the deaths of all 118 men on board.
- August 14 - The first comic of Megatokyo goes online. This webcomic will later become one of the most popular comics on the web (in terms of page views) and spawn numerous imitators.
- August 25 - the Emulex hoax - wire services publish fraudulent bad news about Emulex
- August 27 - The Ostankino Tower in Moscow catches fire, three people are killed.

September


- September 5 - Tuvalu joins the United Nations.
- September 6 - In New York City, the United Nations Millennium Summit begins with more than 180 world leaders present.
- September 6 - The last wholly Swedish-owned arms manufacturer, Bofors, is sold to American arms manufacturer United Defense
- September 7–14 - The UK fuel protests take place, with refineries blockaded, and supply to the country's network of petrol stations halted.
- September 8 - Albania officially joins the World Trade Organization.
- September 15 - The 2000 Summer Olympics are opened in Sydney, Australia.
- September 16 - Ukrainian journalist Georgiy Gongadze is last seen alive; this day is taken as the commemoration date of his death.
- September 24 - The American Family Association begins lobbying the U.S. Congress to eradicate the National Endowment for the Arts for funding the controversial book One of the Guys by Robert Clark Young
- September 26 - Anti-globalization protests in Prague (some 15,000 protesters) turned violent during the IMF and World Bank summits.
- September 28 - Ariel Sharon leads several hundred armed Israelis in a visit to the Temple Mount. Palestinian civil disorder increases into the Al-Aqsa Intifada.
- September 29 - The Long Kesh prison in Northern Ireland is closed.

October


- October 2 NBC Today Show expanded it to three hours (7:00–10:00 A.M. Eastern Time/Pacific Time; 6:00–9:00 A.M. Central Time/Mountain Time)
- October 5 - President Slobodan Milošević leaves office after widespread demonstrations throughout Serbia and the withdrawal of Russian support.
- October 11 - 250 million gallons of coal sludge spill in Martin County, Kentucky. Considered a greater environmental disaster than the Exxon Valdez oil spill.
- October 12 - In Aden, Yemen, the USS Cole is badly damaged by two suicide bombers who placed a small boat laden with explosives along-side the United States Navy destroyer, killing 17 crew members and wounding at least 39.
- October 21 15 Arab leaders convened in Cairo, Egypt, for their first summit in four years; the Libyan delegation walked out, angry over signs the summit would stop short of calling for breaking ties with Israel.
- October 22 – Mainichi Shinbun exposes Japanese archeologist Shinichi Fujimura as a fraud; Japanese archaeologists had based their treatises of his findings.
- October 26 - Pakistani authorities announce that their police have found an apparently ancient mummy of a persian princess in the province of Baluchistan. Iran, Pakistan and the Taliban all claim the mummy until Pakistan announces it is a forgery in April 17 2001
- October 31 - Singapore Airlines Flight 006 collides with construction equipment in the Chiang Kai Shek International Airport - 83 dead.
- October 31 - The last Jeremy clone has shut down.

November

November
- November - Iraq disarmament crisis: Iraq rejects new U.N. Security Council weapons inspections proposals
- November 1 - Yugoslavia's new democratic government joined the United Nations after eight years of U.N. ostracism under former strongman Slobodan Milosevic.
- November 3 - Widespread flooding throughout England and Wales after days of heavy rain
- November 4 - President Clinton vetoed a bill that would have criminalized the leaking of government secrets.
- November 7 - U.S. presidential election, 2000: Republican challenger George W. Bush defeats Democrat Vice President Al Gore, but the final outcome is not known for over a month because of disputed votes in Florida.
- November 7 - Criminal gang raids the Millennium Dome to steal The Millennium Star diamond but police surveillance catches them in the act
- November 7 - Hillary Rodham Clinton is elected to the United States Senate, becoming the first First Lady of the United States to win public office
- November 11 - Kaprun disaster, Austria, where 155 skiers and snowboarders die when a cable car catches fire in an alpine tunnel.
- November 13 - Richard C. Duncan presents his paper, "The Peak Of World Oil Production And The Road To The Olduvai Gorge", on the Olduvai theory (about the collapse of the industrial civilization), at the Summit 2000 Pardee Keynote Symposia of the Geological Society of America)
- November 14 - Netscape version 6.0 is launched following two years of open source development creating a stable Mozilla web browser upon which it is based
- November 16 - Bill Clinton becomes the first sitting US President to visit Vietnam
- November 17 - Catastrophical landslide in Log pod Mangartom,Slovenia, kills 7, and causes millions of SIT of damage. It is one of the worst catastrophies in Slovenia in the past 100 years.
- November 17 - Alberto Fujimori is removed from office as president of Peru
- November 27 - Canada - Parliamentary elections - Jean Chrétien re-elected as Prime Minister as Liberal Party increases majority in House of Commons
- November 28 - Ukrainian politician Oleksander Moroz touches off the Cassette Scandal by publicly accusing President Leonid Kuchma of involvement in the murder of journalist Georgiy Gongadze.

December


- December 1 - Mexico - Vicente Fox becomes the first opposition President to take office since Francisco I. Madero in 1911. He wins the Presidency as candidate of the rightist PAN (National Action Party).
- December 28 - U.S. retail giant Montgomery Ward announces it is going out of business after 128 years.
- December 30 - Rizal Day Bombings: A series of bombs explode in various places in Metro Manila, Philippines, within a span of a few hours killing 22 and injuring about a hundred.

Unknown Date


- Limited reintroduction of routinely armed police in the UK for the first time since 1936.
- Scientists at University of Szeged's laboratory were first in the world to produce artificial heredity material.
- Millie I. Webb elected president of Mothers Against Drunk Driving.

Births


- February 23 - Max & Sam Christy, American actors
- March 15- Amy and Emily Walton, English actresses
- April 25 - Jacob & Joshua Rips, American actors
- October 6 - Amanda Pace, American actress
- October 20 - Cooper and Oliver Guynes, American actors
- November 8 - Madison and Marissa Poer, actresses

Deaths

January


- January 2 - Patrick O'Brian, English writer (b. 1914)
- January 15 - Fran Ryan, American actress (b. 1916)
- January 19 - Bettino Craxi, Prime Minister of Italy (b. 1934)
- January 19 - Hedy Lamarr, Austrian actress (b. 1913)

February


- February 9 - Beau Jack, American boxer (b. 1921)
- February 11 - Roger Vadim, French film director (b. 1928)
- February 12 - Jalacy "Screamin' Jay" Hawkins, American musician (b. 1929)
- February 12 - Tom Landry, American football coach (b. 1924)
- February 12 - Charles M. Schulz, American comic strip artist (b. 1921)
- February 23 - Sir Stanley Matthews, English footballer (b. 1915)

April


- April 6 - Habib Bourguiba, President of Tunisia (b. 1903)
- April 16 - Tuanku Syed Putra ibni Almarhum Syed Hassan Jamalullail, King of Malaysia (b. 1920)
- April 25 - David Merrick, American stage producer (b. 1911)
- April 29 - Phạm Văn Ðồng, Prime Minister of Vietnam (b. 1906)

May


- May 11 - Paula Wessely, Austrian actress (b. 1907)
- May 12 - Adam Petty, American race car driver (b. 1980)
- May 14 - Keizo Obuchi, Prime Minister of Japan (b. 1937)
- May 17 - Donald Coggan, Archbishop of Canterbury (b. 1909)
- May 19 - Yevgeny Khrunov, cosmonaut

Pencil

A pencil is a handheld instrument used to write and draw, usually on paper. The writing is done with graphite (except for colored pencils), which is typically covered by a wooden sheath. Pencils may also have an eraser or "rubber" attached to one end, typically by means of a metal ferrule. The pencil differs from most pens in that erasing is possible.

History

pen The prototypical pencil may have been the ancient Roman stylus, which was a thin metal stick used for scratching on papyrus, often made of lead. The word pencil comes from the Latin word penicillus which means "little tail". Some time prior to 1565 (some sources say as early as 1500), an enormous deposit of graphite was discovered at the site of Seathwaite Fell near Borrowdale, Cumbria, England. The locals found that it was very useful for marking sheep. This particular deposit of graphite was extremely pure and solid and it could easily be sawed into sticks. This was and remains the only deposit of graphite ever found in this solid form. Chemistry was in its infancy and the substance was thought to be a form of lead. Consequently it was called plumbago (Latin for "acts like lead"). The black core of pencils is still called "lead", even though it does not contain the element lead. The value of plumbago was soon realised to be enormous, mainly because it could be used to line the moulds for cannon balls, and the mines were taken over by the Crown and guarded. Graphite had to be smuggled out for use in pencils. Because the plumbago was soft, it required some form of case. Plumbago sticks were at first wrapped in string or in sheepskin for stability. The news of the usefulness of these early pencils spread far and wide, attracting the attentions of artists all over the known world. Although deposits of graphite had been found in other parts of the world, they were not of the same purity and quality as the Borrowdale find, and had to be crushed to remove the impurities, leaving only graphite powder. England continued to enjoy a monopoly on the production of pencils until a method of reconstituting the graphite powder was found. The distinctively square English pencils continued to be made with sticks cut from natural graphite into the 1860s. Today, the town of Keswick, near the original findings of block graphite, has a pencil museum. The first attempt to manufacture graphite sticks from powdered graphite was in Nuremberg, Germany in 1662. They used a mixture of graphite, sulfur and antimony. Though usable they were inferior to the English pencils. antimony It was the Italians who first thought of wooden holders. An Italian couple in particular named Simonio and Lyndiana Bernacotti were believed to be the the ones to create the first blueprints for the modern carpentry pencil for the cause of being able to mark their carpentry pieces, however, their version was instead a flat oval, more compact type of pencil. They did this at first by hollowing out a stick of juniper wood. Shortly thereafter, a superior technique was discovered: two wooden halves were carved, a plumbago stick inserted, and the two halves then glued together—essentially the same method that is in use to this day. English and German pencils were not available to the French during the Napoleonic wars. It took the efforts of an officer in Napoleon's army to change this. In 1795 Nicholas Jacques Conté discovered a method of mixing powdered graphite with clay and forming the mixture into rods which were then fired in a kiln. By varying the ratio of graphite to clay, the hardness of the graphite rod could also be varied (the more clay, the harder the pencil, and the lighter the color of the mark). This method of manufacture remains in use today. America colonists imported pencils from Europe until after the American Revolution. Benjamin Franklin advertised pencils for sale in his Pennsylvania Gazette in 1729, and George Washington used a three-inch pencil when he surveyed the Ohio Territory in 1762. It is said that William Munroe, a cabinetmaker in Concord, Massachusetts, made the first American wood pencils in 1812. If so, this was not the only pencil-making in Concord. According to Henry Petroski, transcendentalist philosopher Henry David Thoreau discovered how to make a good pencil out of inferior graphite using clay as the binder; this invention was prompted by his father's pencil factory in Concord, which employed graphite found in New Hampshire in 1821 by Charles Dunbar.

Manufacture

New Hampshire Today, pencils are made industrially by mixing finely ground graphite and clay powders, adding water, forming long spaghetti-like strings, and firing them in a kiln. The resulting strings are dipped in oil or molten wax which seeps into the tiny holes of the material, resulting in smoother writing. A juniper or incense-cedar plank with several long parallel grooves is cut to make something called a slat, and the graphite/clay strings are inserted into the grooves. Another grooved plank is glued on top, and the whole thing is then cut into individual pencils, which are then varnished or painted. Many pencils, particularly those used by artists, are labelled on the European system using a scale from "H" (for hardness) to "B" (for blackness), as well as "F" (for fine point). The standard writing pencil is "HB". However, artist's pencils can vary widely in order to provide a range of marks for different visual effects on the page. A set of art pencils ranging from a very hard, light-marking pencil to a very soft, black-marking pencil usually ranges from hardest to softest as follows: 9H 8H 7H 6H 5H 4H 3H 2H H F HB B 2B 3B 4B 5B 6B 7B 8B 9B The American system, using numbers only, developed simultaneously with the following approximate equivalents to the European system. U.S. Europe #1 = B #2 = HB (most common) #2 1/2 = F (also seen as 2 4/8, 2.5, 2 5/10, due to patent issues) #3 = H #4 = 2H Even though the natural deposits of pure graphite are tapped out, it is still possible to write the way Englishmen did centuries ago, without clay or wax additives leaving oily stains on paper. Chemical supply companies commonly sell 99.995% pure graphite rods in 3 mm and 6 mm diameters. The largest commonly available mechanical pencils ("lead holders") take 2 mm leads.

Pencils in space

A story in circulation since the 1970s tells of NASA spending large sums of money, typically in the millions of dollars, to develop an instrument that would write in space (a space pen). This task is not as simple as it seems, for standard ballpoints and fountain pens require gravity in order to function. The typical punch line is that either someone sends NASA a pencil, or that the Soviets used pencils. This second form appeared as a joke as high up as an episode of The West Wing. While humorous, it is not true (See [http://www.snopes.com/business/genius/spacepen.asp Snopes] for details). There are drawbacks to using pencils in space. The act of writing would cause graphite dust to come free from the lead and float about the cabin. From there it could become a health risk by being inhaled by the astronauts, clog filters in the ventilation system, or even cause short-circuits by getting into switches and other electrical equipment.

Carpenter's pencil

A carpenter's pencil is not round or square. It appears as though it were a flattened circle. This shape performs two functions; a flat pencil does not roll away from the user, and a flatter pencil marks a line closer to the cutting edge, allowing for a more precise cut.

Miscellaneous

The pencil is a common cause of minor puncture injuries in young children. The tip of the lead may leave a grey mark inside the skin for years. This led to the old-wife's tale that the lead bits could be passed through the blood vessels into the brain, causing retardation in those with such a wound. Of course, pencil lead is graphite (carbon) and does not contain the element lead, so it is not poisonous, despite what teachers have been telling school children for decades.

See also


- Ballpoint pen
- Dixon Ticonderoga
- Fountain pen
- Mechanical pencil
- Pencil case
- Pencil lead
- Pencil sharpener

References


- Petroski, Henry (1990). The Pencil: A History of Design and Circumstance. New York: Alfred A. Knopf. ISBN 0394574222; ISBN 0679734155.
- Petroski, Henry. H. D. Thoreau, Engineer. American Heritage of Invention and Technology, Vol. 5, No. 2, pp. 8-16.

External links


- [http://pencils.smoky.ca/ paper and pencil]
- [http://www.pencilpages.com/ The Pencil Pages] – A website containing history, numbering systems, and other pencil information
- [http://pencilrevolution.com/ Pencil Revolution]
- [http://www.dibujosparapintar.com/english_activities/drawing_course_pencil.html Pencil information] More information about the pencils.
- [http://www.pencils.co.uk/ The Cumberland Pencil Museum in Keswick]
- [http://pubs.acs.org/cen/whatstuff/stuff/7942sci4.html History of pencils, pencil lead; details of modern pencil manufacture] – An article from the American Chemical Society Category:Art materials Category:Writing instruments Category:Stationery Category:Pencils ko:연필 ms:Pensil ja:鉛筆 simple:Pencil

Acre

:This article is about the unit of measure known as the acre. For other definitions, see Acre (disambiguation). An acre is an English unit of area. It is most frequently used to describe areas of land.

UK definition

The UK has a definition of the acre in [http://www.opsi.gov.uk/si/si1995/Uksi_19951804_en_2.htm The Units of Measurement Regulations 1995] as 4,046.856422 4 m². This is equivalent to 43,560 square feet using the definition of foot in the same source.

US definition

The US has a definition of the acre in [http://ts.nist.gov/ts/htdocs/230/235/appxc/appxc.htm NIST Handbook 44] as 43,560 square feet. However, the US has two definitions of foot (international foot and survey foot) and thus two definitions of acre:
- The international acre is 4,046.856422 4 m². This is based on international foot of 0.3048 m.
- The US survey acre is 4,046.87261 m². This is based on the US survey foot of 1200/3937 m.

Related linear measurements

Two obsolete, but related, measurements are the acre's length and the acre's breadth.
- 1 acre's length = 1 furlong, 40 poles, or 220 yards
- 1 acre's breadth = 1 chain, 4 poles, or 22 yards

Conversion

An international acre is equivalent to exactly:
- 4 046.856 422 4 m² (SI unit)
- 40.468 564 224 a,
- 0.404 685 642 24 ha,
- 43 560 square feet,
- 4840 square yards,
- 160 square rods,
- 4 rood,
- 1/640 square mile,
- a 10:1 rectangle of 1 furlong by 1 chain.
- 10 square chains. An acre is equivalent to approximately:
- a square of side 208.71 feet (63.61 metres). One square mile is 640 acres. A square parcel of land ¼ mile wide is 40 acres. A square parcel of land ½ mile on a side is 160 acres, the usual land tract under the Homestead Act in the United States. This results in common field lengths of ½ mile, with every rod in width equal to one acre. An American Football field covers approximately 1.32 acres.

History

The acre was selected as approximately the amount of land tillable by one man behind an ox in one day. This explains its rectangular definition one-chain by one-furlong parcel of land; a long narrow strip of land is more efficient to plough than a square plot, since the plough does not have to be turned so often. Statutory values were enacted in England by acts of
- Edward I,
- Edward III,
- Henry VIII,
- George IV and
- Victoria - the British "Weights and Measures Act" of 1878 defined it as containing 4840 square yards.

See also


- Conversion of units
- Acre-foot
- Acre (Scots)

External links


- [http://www.opsi.gov.uk/si/si1995/Uksi_19951804_en_2.htm The Units of Measurement Regulations 1995]
- [http://ts.nist.gov/ts/htdocs/230/235/appxc/appxc.htm NIST Handbook 44] Category:Units of area Category:Imperial units Category:Customary units in the United States Category:Real estate ja:エーカー

1855

1855 was a common year starting on Monday (see link for calendar).

Events


- January 1 - London, Ontario is incorporated as a city.
- January 23 - The first bridge over the Mississippi River opens in what is now Minneapolis, Minnesota, a crossing made today by the Father Louis Hennepin Bridge.
- January 23 - The region of Wairarapa, New Zealand was hit by the strongest earthquake ever recorded in New Zealand, which reached Magnitude 8.1 on the Richter Scale. There were five deaths.
- January 29 - Lord Aberdeen resigns as Prime Minister of the United Kingdom over the management of the Crimean War.
- February 5 - Lord Palmerston becomes Prime Minister of the United Kingdom
- February 11 - Kassa Hailu is crowned Tewodros II, Emperor of Ethiopia, by Abuna Salama III in a ceremony at the church of Derasge Maryam.
- March 3 - US Congress appropriates $30,000 to create US Camel Corps
- May 15 - The Great Gold Robbery of 1855 in England
- June 29 - The Daily Telegraph begins publication
- September 3 - Last Bartholomew Fair on London, England
- September 11 - Sevastapol falls to the British troops
- Stamp duty was removed from newspapers in Britain creating mass market media in the UK.
- The Panama Railway becomes the first railroad to connect the Atlantic Ocean and Pacific Ocean by rail as the railroad's route across Panama is completed.

Births


- January 5 - King Camp Gillette, American inventor (d. 1932)
- January 20 - Ernest Chausson, French composer (d. 1899)
- January 21 - John Moses Browning, American firearms inventor (d. 1926)
- January 28 - William Seward Burroughs, American bank clerk and inventor (d. 1898)
- March 13 - Percival Lowell, American astronomer (d. 1916)
- March 24 - Andrew Mellon, American banker and philanthropist (d. 1937)
- April 21 - Hardy Richardson, 19th century baseball player (d. 1931)
- April 27 - Caroline Rémy, French feminist (d. 1929)
- May 1 - Marie Corelli, English novelist (d. 1924)
- July 26 - Ferdinand Tönnies, German sociologist (d. 1936)
- October 21 - Howard Hyde Russell, American temperance movement leader and founder of Anti-Saloon League and Lincoln-Lee Legion (d. 1946)
- November 5 - Léon Teisserenc de Bort, French meteorologist (d. 1913)
- November 6 - Ezra Seymour Gosney, American philanthropist and eugenicist (d. 1942)

Deaths


- January 6 - Giacomo Beltrami, Italian explorer, gaylord (b. 1779)
- January 26 - Gérard de Nerval, French writer (b. 1808)
- February 6 - Josef Munzinger, member of the Swiss Federal Council (b. 1791)
- February 23 - Carl Friedrich Gauss, German mathematician, astronomer, and physicist (b. 1777)
- March 29 - Henri Druey, member of the Swiss Federal Council (b. 1799)
- March 31 - Charlotte Brontë, English author (b. 1816)
- May 5 - Robert Inglis, English politician (b. 1786)
- May 23 - Charles Robert Malden English explorer (b. 1797)
- June 28 - Fitzroy Somerset, 1st Lord Raglan, commander of British forces in the Crimean War (b. 1788)
- August 7 - Mariano Arista, President of Mexico (b. 1802)
- November 11 - Søren Kierkegaard, Danish philosopher (b. 1813)
- November 26 - Adam Mickiewicz, Lithuanian - Polish poet and writer (b. 1798)
- Metropolitan Board of Works established. Category:1855 ko:1855년 ms:1855 th:พ.ศ. 2398

Hurricane

:Hurricane and Typhoon redirect here. For other uses, see Hurricane (disambiguation) and Typhoon (disambiguation). Typhoon (disambiguation) on March 26, 2004.]] In meteorology, a tropical cyclone (or tropical depression, tropical storm, typhoon, or hurricane, depending on strength and geographical context) is a type of low pressure system which generally forms in the tropics. While they can be highly destructive, tropical cyclones are an important part of the atmospheric circulation system, which moves heat from the equatorial region toward the higher latitudes.

Terms for tropical cyclones

equatorial region]] Depending on the region, different terms are used to describe tropical cyclones with maximum sustained winds exceeding 33 meters per second (63 knots, 73 mph, or 117 km/h):
- hurricane in the North Atlantic Ocean, North Pacific Ocean east of the dateline
- typhoon in the Northwest Pacific Ocean west of the dateline
- severe tropical cyclone in the Southwest Pacific Ocean west of 160°E or Southeast Indian Ocean east of 90°E
- severe cyclonic storm in the North Indian Ocean
- tropical cyclone in the Southwest Indian Ocean and South Pacific Ocean east of 160°E.
- cyclone unofficially in the South Atlantic Ocean In other areas, hurricanes have been called Baguio in the Philippines and Taino in Haiti.

Etymology

The word typhoon has two possible origins:
- From the Chinese 大風 (daaih fūng (Cantonese); dà fēng (Mandarin)) which means "great wind". (The Chinese term as 颱風 táifēng, and 台風 taifu in Japanese, has an independent origin traceable variously to 風颱, 風篩 or 風癡 hongthai, going back to Song 宋 (960-1278) and Yuan 元(1260-1341) dynasties. The first record of the character 颱 appeared in 1685's edition of Summary of Taiwan 臺灣記略).
- From Urdu, Persian or Arabic ţūfān (طوفان) < Greek tuphōn (Τυφών). Portuguese tufão is also related to typhoon. See tuphōn for more information. The word hurricane is derived from the name of a native Caribbean Amerindian storm god, Huracan, via Spanish huracán. The word cyclone came from the Greek word "κύκλος", meaning "circle".

Mechanics of a tropical cyclone

Spanish. The air heats up, rising further, which leads to more condensation. The air flowing out of the top of this “chimney” drops towards the ground, forming powerful winds.]] Structurally, a tropical cyclone is a large, rotating system of clouds, wind and thunderstorm activity. Its primary energy source is the release of the heat of condensation from water vapor condensing at high altitudes, the heat ultimately derived from the sun. Therefore, a tropical cyclone can be thought of as a giant vertical heat engine supported by mechanics driven by physical forces such as the orbital revolution and gravity of the Earth. Continued condensation leads to higher winds, continued evaporation, and continued condensation, feeding back into itself. This gives rise to factors that give the system enough energy to be self-sufficient and cause a positive feedback loop where it can draw more energy as long as the source of heat, warm water, remains. Factors such as a continued lack of equilibrium in air mass distribution would also give supporting energy to the cyclone. The orbital revolution of the Earth causes the system to spin, giving it a cyclone characteristic and affecting the trajectory of the storm. The factors to form a tropical cyclone include a pre-existing weather disturbance, warm tropical oceans, moisture, and relatively light winds aloft. If the right conditions persist and allow it to create a feedback loop by maximizing the energy intake possible, for example, such as high winds to increase the rate of evaporation, they can combine to produce the violent winds, incredible waves, torrential rains, and floods associated with this phenomenon. Condensation as a driving force is what primarily distinguishes tropical cyclones from other meteorological phenomena, and because this is strongest in a tropical climate, this defines the initial domain of the tropical cyclone. By contrast, mid-latitude cyclones, for example, draw their energy mostly from pre-existing horizontal temperature gradients in the atmosphere. In order to continue to drive its heat engine, a tropical cyclone must remain over warm water, which provides the atmospheric moisture needed. The condensation of this moisture is driven by the high winds and reduced atmospheric pressure in the storm, resulting in a sustaining cycle. As a result, when a tropical cyclone passes over land, its strength diminishes rapidly. Scientists at the National Center for Atmospheric Research estimate that a hurricane releases heat energy at the rate of 50 to 200 trillion watts -- about the amount of energy released by exploding a 10-megaton nuclear bomb every 20 minutes [http://www.ucar.edu/news/features/hurricanes/index.shtml].

Formation

nuclear bomb The formation of tropical cyclones is the topic of extensive ongoing research, and is still not fully understood. Five factors are necessary to make tropical cyclone formation possible: # Sea surface temperatures above 26.5 degrees Celsius (79.7 degrees Fahrenheit) to at least a depth of 50 meters (164 feet). The moisture in the air above the warm water is the energy source for tropical cyclones. # Upper-atmosphere conditions conducive to thunderstorm formation. Temperature in the atmosphere must decrease quickly with height, and the mid-troposphere must be relatively moist. # A pre-existing weather disturbance. This is most frequently provided by tropical waves—non-rotating areas of thunderstorms that move through tropical oceans. # A distance of approximately 10 degrees or more from the equator, so that the Coriolis effect is strong enough to initiate the cyclone's rotation. (2004's Hurricane Ivan was the strongest storm to form closer than 10 degrees from the equator; it started forming at 9.7 degrees north.) # Low vertical wind shear (change in wind speed or direction over height). High wind shear can break apart the vertical structure of a tropical cyclone. Tropical cyclones occasionally form despite not meeting these conditions. Only specific weather disturbances can result in tropical cyclones. These include: # Tropical waves, or easterly waves, which, as mentioned above, are westward moving areas of convergent winds. This often assists in the development of thunderstorms, which can develop into tropical cyclones. Most tropical cyclones form from these. A similar phenomenon to tropical waves are West African disturbance lines, which are squally lines of convection that form over Africa and move into the Atlantic. # Tropical upper tropospheric troughs, which are cold-core upper level lows. A warm-core tropical cyclone may result when one of these (on occasion) works down to the lower levels and produces deep convection. # Decaying frontal boundaries may occasionally stall over warm waters and produce lines of active convection. If a low level circulation forms under this convection, it may develop into a tropical cyclone.

When do tropical cyclones form?

Worldwide, tropical cyclone activity peaks in late summer when water temperatures are warmest. However, each particular basin has its own seasonal patterns. In the North Atlantic, a distinct hurricane season occurs from June 1 to November 30, sharply peaking from late August through September. The statistical peak of the North Atlantic hurricane season is September 10. The Northeast Pacific has a broader period of activity, but in a similar timeframe to the Atlantic. The Northwest Pacific sees tropical cyclones year-round, with a minimum in February and a peak in early September. In the North Indian basin, storms are most common from April to December, with peaks in May and November. In the Southern Hemisphere, tropical cyclone activity begins in late October and ends in May. Southern Hemisphere activity peaks in mid-February to early March. Worldwide, an average of 80 tropical cyclones form each year.

Where do tropical cyclones form?

Most tropical cyclones form in a worldwide band of thunderstorm activity called the Intertropical convergence zone (ITCZ). Nearly all of them form between 10 and 30 degrees of the equator and 87% form within 20 degrees of it. Because the Coriolis effect initiates and maintains tropical cyclone rotation, such cyclones almost never form or move within about 10 degrees of the equator [http://www.bom.gov.au/bmrc/pubs/tcguide/ch1/figures_ch1/figure1.9.htm], where the Coriolis effect is weakest. However, it is possible for tropical cyclones to form within this boundary if there is another source of initial rotation. These conditions are extremely rare, and such storms are believed to form at most once per century. Hurricane Ivan of 2004 developed within 10 degrees of the equator. A combination of a pre-existing disturbance, upper level divergence and a monsoon-related cold spell led to Typhoon Vamei at only 1.5 degrees north of the equator in 2001. It is estimated that such conditions occur only once every 400 years.

Major basins

There are seven main basins of tropical cyclone formation:
- North Atlantic Basin: The most-studied of all tropical basins, it includes the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. Tropical cyclone formation here varies widely from year to year, ranging from over twenty to one per year. The average is about ten. The United States Atlantic coast, Mexico, Central America, the Caribbean Islands and Bermuda are frequently affected by storms in this basin. Venezuela, the south-east of Canada and Atlantic "Macaronesian" islands are also occasionally affected. The U.S. National Hurricane Center (NHC) based in Miami, Florida, issues forecasts for storms for all nations in the region; the Canadian Hurricane Centre, based in Halifax, Nova Scotia, also issues forecasts and warnings for storms expected to affect Canadian territory and waters. Hurricanes that strike Mexico, Central America, and Caribbean island nations, often do intense damage, as hurricanes are deadlier over warmer water. Additionally, they can hit the coast of the U.S., especially Florida, North Carolina, the U.S. Gulf Coast and occasionally New Jersey, New York and New England (usually hurricanes weaken to tropical storms before they reach these northern regions). The coast of Atlantic Canada receives hurricane landfalls on rare occasion, such as Hurricane Juan in 2003. Many of the more intense Atlantic storms are Cape Verde-type hurricanes, which form off the west coast of Africa near the Cape Verde islands.
- Western North Pacific Ocean: Tropical storm activity in this region frequently affects China, Japan, the Philippines, and Taiwan, but also many other countries in South-East Asia, such as Vietnam, South Korea and Indonesia, plus numerous Oceanian islands. This is by far the most active basin, accounting for one-third of all tropical cyclone activity in the world. The eastern coasts of Taiwan and Philippines also have the highest tropical cyclone landfall frequency in the world. National meteorology organizations and the Joint Typhoon Warning Center (JTWC) are responsible for issuing forecasts and warnings in this basin.
- Eastern North Pacific Ocean: This is the second most active basin in the world, and the most dense (a large number of storms for a small area of ocean). Storms that form here can affect western Mexico, Hawaii, northern Central America, and on extremely rare occasions, California. In the U.S., the Central Pacific Hurricane Center is responsible for forecasting the western part of this area while the National Hurricane Center is responsible for the eastern part.
- South Western Pacific Ocean: Tropical activity in this region largely affects Australia and Oceania, and is forecast by Australia and Papua New Guinea.
- Northern Indian Ocean: This basin is divided into two areas, the Bay of Bengal and the Arabian Sea, with the Bay of Bengal dominating (5 to 6 times more activity). This basin's season has an interesting double peak; one in April and May before the onset of the monsoon, and another in October and November just after. Hurricanes which form in this basin have historically cost the most lives — most notably, the 1970 Bhola cyclone killed 200,000. Nations affected by this basin include India, Bangladesh, Sri Lanka, Thailand, Myanmar, and Pakistan, and all of these countries issue regional forecasts and warnings. Rarely, a tropical cyclone formed in this basin will affect the Arabian Peninsula.
- Southeastern Indian Ocean: Tropical activity in this region affects Australia and Indonesia, and is forecast by those nations.
- Southwestern Indian Ocean: This basin is the least understood, due to a lack of historical data. Cyclones forming here impact Madagascar, Mozambique, Mauritius, and Kenya, and these nations issue forecasts and warnings for the basin.

Unusual formation areas

Kenya at 2300 UTC near the Madeira Islands.]] The following areas spawn tropical cyclones only very rarely.
- Southern Atlantic Ocean: A combination of cooler waters, the lack of an ITCZ, and wind shear makes it very difficult for the Southern Atlantic to support tropical activity. However, three tropical cyclones have been observed here — a weak tropical storm in 1991 off the coast of Africa, Hurricane Catarina (sometimes also referred to as Aldonça), which made landfall in Brazil in 2004 as a Category 1 hurricane, and a smaller storm in January 2004, east of Salvador, Brazil. The January storm is thought to have reached tropical storm intensity based on scatterometre winds.
- Central North Pacific: Shear in this area of the Pacific Ocean severely limits tropical development. However, this region is commonly frequented by tropical cyclones that form in the much more favorable Eastern North Pacific Basin.
- Eastern South Pacific: Tropical cyclones are rare in this region; activity is frequently linked to El Niño episodes. When they do form, they can affect the islands of Polynesia.
- Mediterranean Sea: Storms which appear similar to tropical cyclones in structure sometimes occur in the Mediterranean basin. Such cyclones formed in September 1947, September 1969, January 1982, September 1983, and January 1995. However, there is debate on whether these storms were tropical in nature.
- Northeastern Atlantic Ocean: In October 2005, Hurricane Vince formed near Madeira, then moved northeastward, passing south of the Portuguese south coast, and made landfall in southwestern Spain as a tropical storm. Vince's origin was the northernmost in the eastern Atlantic ever recorded, and Vince was the first storm in recorded history to reach the Iberian Peninsula as a tropical cyclone, i.e. before being transformed into an extratropical low or absorbed into other systems of low pressure.
- Australia: SW Pacific Basin includes the eastern part of Australia and the Fiji area.
- Australia: SE Indian Basin includes the eastern part of the Indian ocean and the northern and western part of the Australian basin.
- Southern South China Sea Tropical cyclones normally do not develop in the Southern South China Sea due to its close proximity to the equator. Areas within ten degrees laditude of the equator do not experience a significant coriolis force, a vital ingredient in tropical cyclone formation. However, in December 2001, Typhoon Vamei formed in the Southern South China Sea and made landfall in Malaysia. It caused flooding in southern Malaysia and some damage in Singapore. It formed from a thunderstorm formation in Borneo that moved into the South China Sea.

Average Season

Structure and classification

Borneo A strong tropical cyclone consists of the following components.
- Surface low: All tropical cyclones rotate around an area of low atmospheric pressure near the Earth's surface. The pressures recorded at the centers of tropical cyclones are among the lowest that occur on Earth's surface at sea level.
- Warm core: Tropical cyclones are characterized and driven by the release of large amounts of latent heat of condensation as moist air is carried upwards and its water vapor condenses. This heat is distributed vertically, around the center of the storm. Thus, at any given altitude (except close to the surface where water temperature dictates air temperature) the environment inside the cyclone is warmer than its outer surroundings.
- Central Dense Overcast (CDO): The Central Dense Overcast is a dense shield of very intense thunderstorm activity that make up the inner portion of the hurricane. This contains the eye wall, and the eye itself. The classic hurricane contains a symmetrical CDO, which means that it is perfectly circular and round on all sides.
- Eye: A strong tropical cyclone will harbor an area of sinking air at the center of circulation. Weather in the eye is normally calm and free of clouds (however, the sea may be extremely violent). Eyes are home to the coldest temperatures of the storm at the surface, and the warmest temperatures at the upper levels. The eye is normally circular in shape, and may range in size from 8 km to 200 km (5 miles to 125 miles) in diameter. In weaker cyclones, the CDO covers the circulation center, resulting in no visible eye.
- Eyewall: It is the area directly around the eye of the cyclone where the winds are the highest, the clouds reach furthest into the atmosphere and the precipitation is the heaviest. The heaviest damage caused by tropical cyclones occurs where the eyewall crosses over land.
- Outflow: The upper levels of a tropical cyclone feature winds headed away from the center of the storm with an anticyclonic rotation. Winds at the surface are strongly cyclonic, weaken with height, and eventually reverse themselves. Tropical cyclones owe this unique characteristic to the warm core at the center of the storm.

Types of tropical cyclones

Tropical cyclones are classified into three main groups: tropical depressions, tropical storms, and a third group whose name depends on the region. A tropical depression is an organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of less than 17 metres per second (33 knots, 38 mph, or 62 km/h). It has no eye, and does not typically have the spiral shape of more powerful storms. It is already becoming a low-pressure system, however, hence the name "depression". A tropical storm is an organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds between 17 and 33 meters per second (34–63 knots, 39–73 mph, or 62–117 km/h). At this point, the distinctive cyclonic shape starts to develop, though an eye is usually not present. Government weather services assign first names to systems that reach this intensity (thus the term named storm). At hurricane intensity, a tropical cyclone tends to develop an eye, an area of relative calm (and lowest atmospheric pressure) at the center of the circulation. The eye is often visible in satellite images as a small, circular, cloud-free spot. Surrounding the eye is the eyewall, an area about 10 to 50 miles (16 to 80 kilometers) wide in which the strongest thunderstorms and winds circulate around the storm's center. The circulation of clouds around a cyclone's center imparts a distinct spiral shape to the system. Bands or arms may extend over great distances as clouds are drawn toward the cyclone. The direction of the cyclonic circulation depends on the hemisphere; it is counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere. Maximum sustained winds in the strongest tropical cyclones have been measured at more than 85 m/s (165 knots, 190 mph, 305 km/h). Intense, mature hurricanes can sometimes exhibit an inward curving of the eyewall top that resembles a football stadium: this phenomenon is thus sometimes referred to as stadium effect. Eyewall replacement cycles naturally occur in intense tropical cyclones. When cyclones reach peak intensity they usually - but not always - have an eyewall and radius of maximum winds that contract to a very small size, around 5 to 15 miles. At this point, some of the outer rainbands may organize into an outer ring of thunderstorms that slowly moves inward and robs the inner eyewall of its needed moisture and momentum. During this phase, the tropical cyclone is weakening (i.e. the maximum winds die off a bit and the central pressure goes up). Eventually the outer eyewall replaces the inner one completely and the storm can be the same intensity as it was previously or, in some cases, even stronger. While the most obvious motion of clouds is toward the center, tropical cyclones also develop an outward flow of clouds. These originate from air that has released its moisture and is expelled at high altitude through a chimney effect of the storm engine. This outflow produces high, thin cirrus clouds that spiral away from the center. The high cirrus clouds may be the first signs of an approaching hurricane.

Categories and ranking

Hurricanes are ranked according to their maximum winds using the Saffir-Simpson Hurricane Scale. A Category 1 storm has the lowest maximum winds, a Category 5 hurricane has the highest. The rankings are not absolute in terms of effects. Lower-category storms can inflict greater damage than higher-category storms, depending on factors such as local terrain and total rainfall. In fact, tropical systems of less than hurricane strength can produce significant damage and human casualties, especially from flooding and landslides. The National Hurricane Center classifies hurricanes of Category 3 and above as Major Hurricanes. The Joint Typhoon Warning Center classifies typhoons with wind speeds of at least 150 mi/h (67 m/s or 241 km/h, equivalent to a strong Category 4 storm) as Super Typhoons. The definition of sustained winds recommended by the World Meteorological Organization (WMO) and used by most weather agencies is that of a 10-minute average. The U.S. weather service defines sustained winds based on 1-minute average speed measured about 10 meters (33 ft) above the surface.

Other storm systems

An extratropical cyclone is a storm that derives energy from horizontal temperature differences, which are typical in higher latitudes. A tropical cyclone can become extratropical as it moves toward higher latitudes if its energy source changes from heat released by condensation to differences in temperature between air masses. From space, extratropical storms have a characteristic "comma-shaped" cloud pattern. Extratropical cyclones can also be dangerous because their low-pressure centers cause powerful winds. In the United Kingdom and Europe, some severe northeast Atlantic cyclonic depressions are referred to as "hurricanes," even though they rarely originate in the tropics. These European windstorms can generate hurricane-force winds but are not given individual names. However, two powerful extratropical cyclones that ravaged France, Germany, and the United Kingdom in December 1999, "Lothar" and "Martin", were named due to their unexpected power (equivalent to a category 1 or 2 hurricane). In British Shipping Forecasts, winds of force 12 on the Beaufort scale are described as "hurricane force." There is also a polar counterpart to the tropical cyclone, called a polar low.

Movement and track

Large-scale winds

Although tropical cyclones are large systems generating enormous energy, their movements over the earth's surface are often compared to that of leaves carried along by a stream. That is, large-scale winds—the streams in the earth's atmosphere—are responsible for moving and steering tropical cyclones. The path of motion is referred to as a tropical cyclone's track. The major force affecting the track of tropical systems in all areas are winds circulating around high-pressure areas. Over the North Atlantic Ocean, tropical systems are steered generally westward by the east-to-west winds on the south side of the Bermuda High, a persistent high-pressure area over the North Atlantic. Also, in the area of the North Atlantic where hurricanes form, trade winds, which are prevailing westward-moving wind currents, steer tropical waves (precursors to tropical depressions and cyclones) westward from off the African coast toward the Caribbean and North America.

Coriolis effect

The earth's rotation also imparts an acceleration (termed the Coriolis Acceleration or Coriolis Effect). This acceleration causes cyclonic systems to turn towards the poles in the absence of strong steering currents (i.e. in the north, the northern part of the cyclone has winds to the west, and the Coriolis force pulls them slightly north. The southern part is pulled south, but since it is closer to the equator, the Coriolis force is a bit weaker there). Thus, tropical cyclones in the Northern Hemisphere, which commonly move west in the beginning, normally turn north (and are then usually blown east), and cyclones in the Southern Hemisphere are deflected south, if no strong pressure systems are counteracting the Coriolis Acceleration. The Coriolis acceleration also initiates cyclonic rotation, but it is not the driving force that brings this rotation to high speeds. (Much of that is due to the conservation of angular momentum - air is drawn in from an area much larger than the cyclone such that the tiny angular velocity of that air will be magnified greatly when the distance to the storm center shrinks.)

Interaction with high and low pressure systems

Finally, when a tropical cyclone moves into higher latitude, its general track around a high-pressure area can be deflected significantly by winds moving toward a low-pressure area. Such a track direction change is termed recurve. A hurricane moving from the Atlantic toward the Gulf of Mexico, for example, will recurve to the north and then northeast if it encounters winds blowing northeastward toward a low-pressure system passing over North America. Many tropical cyclones along the U.S. East Coast and in the Gulf of Mexico are eventually forced toward the northeast by low-pressure areas which move from west to east over North America.

Track forecasting

Because of the forces that affect tropical cyclone tracks, accurate track predictions depend on determining the position and strength of high- and low-pressure areas, and predicting how those areas will change during the life of a tropical system. With their understanding of the forces that act on tropical cyclones, and a wealth of data from earth-orbiting satellites and other sensors, scientists have increased the accuracy of track forecasts over recent decades. High-speed computers and sophisticated simulation software allow forecasters to produce computer models that forecast tropical cyclone tracks based on the future position and strength of high- and low-pressure systems. But while track forecasts have become more accurate than 20 years ago, scientists say they are less skillful at predicting the intensity of tropical cyclones. They attribute the lack of improvement in intensity forecasting to the complexity of tropical systems and an incomplete understanding of factors that affect their development.

Landfall

Officially, "landfall" is when a storm's center (the center of the eye, not its edge) reaches land. Naturally, storm conditions may be experienced on the coast and inland well before landfall. In fact, for a storm moving inland, the landfall area experiences half the storm before the actual landfall. For emergency preparedness, actions should be timed from when a certain wind speed will reach land, not from when landfall will occur.

Unusual landfall areas

The following areas rarely have a recorded landfall of a tropical cyclone: Europe: Because of the high latitudes, the European mainland have only a handful recorded landfalls made by hurricanes and or tropical storms. Notable examples are Hurricane Debbie of 1961 and Hurricane Vince of 2005. Azores: Like Europe, the Azores have a some recorded landfalls of hurricanes and tropical storms. Canary Islands: Until Tropical Storm Delta of 2005, the Canary Islands were rarely affected by any tropical storm or hurricanes. West African Coast: No recorded landfall of a tropical storm or hurricane although some come close but bypass the area. Cape Verde Islands: Some records of landfall made by a tropical storm or hurricane, most notably 1982's Tropical Storm Beryl that killed 115 people. Venezuela: Rarely a tropical storm or hurricane makes landfall in this country. Notable examples are 1993's Tropical Storm Bret and Hurricane Joan of 1988. California: Rarely a tropical storm or hurricane have ever affected California. Notable storms were a tropical storm in 1939 and a hurricane in 1858. New Zealand: On rare circumstances, a cyclone or two have made landfall in that country.

Dissipation

A tropical cyclone can cease to have tropical characteristics in several ways:
- It moves over land, thus depriving it of the warm water it needs to power itself, and quickly loses strength. Most strong storms become disorganized areas of low pressure within a day or two of landfall. There is, however, a chance they could regenerate if they manage to get back over open warm water. If a storm is over mountains for even a short time, it can rapidly lose strength. This is, however, the cause of many storm fatalities, as the dying storm unleashes torrential rainfall, and in mountainous areas, this can lead to deadly mudslides. The storm loses strength slower over flatter or marshy areas than over mountainous terrain which disrupts the surface circulation of the storm more.
- It remains in the same area of ocean for too long, sucking up all the warm water. Without warm surface water, the storm cannot survive.
- It experiences wind shear, causing the convection to lose direction and the heat engine to break down.
- It can be weak enough to be consumed by another area of low pressure, disrupting it and joining to become a large area of non-cyclonic thunderstorms. (Such, however, can re-strengthen the non-tropical system as a whole.)
- It enters colder waters. This does not necessarily mean the death of the storm, but the storm will lose its tropical characteristics. These storms are extratropical cyclones.
- An outer eye wall forms (typically around 50 miles from the center of the storm), choking off the convection toward the inner eye wall. Such weakening is generally temporary unless it meets other conditions above. Even after a tropical cyclone is said to be extratropical or dissipated, it can still have tropical storm force (or occasionally hurricane force) winds and drop several inches of rainfall. When a tropical cyclone reaches higher latitudes or passes over land, it may merge with weather fronts or develop into a frontal cyclone, also called extratropical cyclone. In the Atlantic ocean, such tropical-derived cyclones of higher latitudes can be violent and may occasionally remain at hurricane-force wind speeds when they reach Europe as a European windstorm.

Artificial dissipation

In the 1960s and 1970s, the United States government attempted to weaken hurricanes in its Project Stormfury by seeding selected storms with silver iodide. It was thought that the seeding would disrupt the storm's eyewall, causing it to collapse and thus reduce the winds. The winds of Hurricane Debbie dropped as much as 30 percent, but then regained their strength after each of two seeding forays. In an earlier episode, disaster struck when a hurricane east of Jacksonville, Florida, was seeded, promptly changed its course, and smashed into Savannah, Georgia. Because there was so much uncertainty about the behavior of these storms, the federal government would not approve seeding operations unless the hurricane had a less than 10 percent chance of making landfall within 48 hours. This placed severe restrictions on the project, and when the Navy pulled out in 1972, it all but killed any further attempts at hurricane seeding in the Atlantic. It was later discovered that eyewall disruption happens naturally as part of eyewall replacement cycles, and so the success of the program was impossible to gauge. Other approaches have been suggested over time, including cooling the water under a tropical cyclone by towing icebergs into the tropical oceans; covering the ocean in a substance that inhibits evaporation; or blasting the cyclone apart with nuclear weapons. These approaches all suffer from the same flaw: tropical cyclones are simply too large for any of them to be practical [http://www.aoml.noaa.gov/hrd/tcfaq/C5f.html]. However, it has been suggested by some that we can change the course of a storm during its early stages of formation, (detailed by an article, Controlling Hurricanes, Scientific American, 2005), such as using satellite to alter the environmental conditions or, more realistically, spreading degradable film of oil over the ocean, which prevent water vapour from fueling the storm.

Monitoring, observation and tracking

Intense tropical cyclones pose a particular observation challenge. As they are a dangerous oceanic phenomenon, weather stations are rarely available on the site of the storm itself. Surface level observations are generally available only if the storm is passing over an island or a coastal area, or it has overtaken an unfortunate ship. Even in these cases, real-time measurement taking is generally possible only in the periphery of the cyclone, where conditions are less catastrophic. It is however possible to take in-situ measurements, in real-time, by sending specially equipped reconnaissan