Effects of tropical cyclones - AbsoluteAstronomy.com

Tropical cyclone

A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...

s include heavy rain

Rain

Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...

, strong wind

Wind

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

, large storm surge

Storm surge

A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...

s at landfall

Landfall (meteorology)

Landfall is the event of a tropical cyclone or a waterspout coming onto land after being over water. When a waterspout makes landfall it is reclassified as a tornado, which can then cause damage inland...

, and tornado

Tornado

A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...

es. The destruction from a tropical cyclone depends mainly on its intensity

Tropical cyclone scales

Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...

, its size, and its location. Tropical cyclones act to remove forest canopy as well as change the landscape near coastal areas, by moving and reshaping sand dunes and causing extensive erosion along the coast. Even well inland, heavy rainfall can lead to mudslides and landslides in mountainous areas. Their effects can be sensed over time by studying the concentration of the Oxygen-18 isotope within caves within the vicinity of cyclones' paths.

After the cyclone

Cyclone

In meteorology, a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth. This is usually characterized by inward spiraling winds that rotate anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere of the Earth. Most large-scale...

has passed, devastation often continues. Standing water can cause the spread of disease, and transportation or communications infrastructure may have been destroyed, hampering clean-up and rescue efforts. Nearly two million people have died globally due to tropical cyclones. Despite their devastating effects, tropical cyclones are also beneficial, by potentially bringing rain to dry areas and moving heat from the tropics poleward. Out at sea, ships take advantage of their known characteristics by navigating through their weaker, western half.

At sea

A mature tropical cyclone can release heat at a rate upwards of 6x10¹⁴ watt

Watt

The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

s. Tropical cyclones on the open sea cause large waves, heavy rain, and high winds, disrupting international shipping and, at times, causing shipwreck

Shipwreck

A shipwreck is what remains of a ship that has wrecked, either sunk or beached. Whatever the cause, a sunken ship or a wrecked ship is a physical example of the event: this explains why the two concepts are often overlapping in English....

s. Generally, after its passage, a tropical cyclone stirs up ocean water, lowering sea surface temperature

Sea surface temperature

Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a...

s behind it. This cool wake can cause the region to be less favorable for a subsequent tropical cyclone. On rare occasions, tropical cyclones may actually do the opposite. 2005

2005 Atlantic hurricane season

The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion...

's Hurricane Dennis

Hurricane Dennis

Hurricane Dennis was an early-forming major hurricane in the Caribbean and Gulf of Mexico during the very active 2005 Atlantic hurricane season. Dennis was the fourth named storm, second hurricane, and first major hurricane of the season...

blew warm water behind it, contributing to the unprecedented intensity of Hurricane Emily

Hurricane Emily (2005)

Hurricane Emily was a powerful, early season tropical cyclone that caused significant damage across the Caribbean Sea to Mexico. A Cape Verde-type hurricane, the storm formed on July 10, 2005, in the central Atlantic Ocean before passing through the Windward Islands on July 14...

, which followed it closely. Hurricanes help to maintain the global heat balance by moving warm, moist tropical air to the mid-latitudes and polar regions. Were it not for the movement of heat poleward (through other means as well as hurricanes), the tropical regions would be unbearably hot.

North American colonization

Shipwrecks are common with the passage of strong tropical cyclones. Such shipwrecks can change the course of history, as well as influence art and literature. A hurricane led to a victory of the Spanish over the French for control of Fort Caroline, and ultimately the Atlantic coast of North America, in 1565. The Sea Venture
Sea Venture
The Sea Venture was a 17th-century English sailing ship, the wrecking of which in Bermuda is widely thought to have been the inspiration for Shakespeare's The Tempest...

was wrecked near Bermuda in 1609 which led to the colonization of Bermuda and provided the inspiration for Shakespeare's

William Shakespeare

William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...

The Tempest.

Shipping

Mariners have a way to safely navigate around tropical cyclones. They split tropical cyclones into two halves, based on its direction of motion. They avoid the right half of the cyclone and termed it the dangerous semicircle since the heaviest rain and strongest winds and seas were located in this half of the storm. The other half of the tropical cyclone was called the navigable semicircle since weather conditions are less extreme in this half of the storm. The rules of thumb for ship travel when a tropical cyclone is in their vicinity are to avoid them if at all possible and do not cross their forecast path (crossing the T). Those travelling through the dangerous semicircle are advised to keep to the true wind on the starboard bow and make as much headway as possible. Ships moving through the navigable semicircle are advised to keep the true wind on the starboard quarter while making as much headway as possible.

Upon landfall

The most significant effects of a tropical cyclone occur when they cross coastlines, making landfall

Landfall (meteorology)

Strong winds

Strong wind

Wind

s can damage or destroy vehicles, buildings, bridges, and other outside objects, turning loose debris into deadly flying projectiles. In the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, major hurricanes

Tropical cyclone scales

Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...

comprise just 21% of all landfalling tropical cyclones, but account for 83% of all damage. Tropical cyclones often knock out power to tens or hundreds of thousands of people, preventing vital communication and hampering rescue efforts. Tropical cyclones often destroy key bridges, overpasses, and roads, complicating efforts to transport food, clean water, and medicine to the areas that need it. Furthermore, the damage caused by tropical cyclones to buildings and dwellings can result in economic damage to a region, and to a diaspora

Diaspora

A diaspora is "the movement, migration, or scattering of people away from an established or ancestral homeland" or "people dispersed by whatever cause to more than one location", or "people settled far from their ancestral homelands".The word has come to refer to historical mass-dispersions of...

of the population of the region.

Storm surge

The storm surge

Storm surge

, or the increase in sea level due to the cyclone, is typically the worst effect from landfalling tropical cyclones, historically resulting in 90% of tropical cyclone deaths. The relatively quick surge in sea level can move miles/kilometers inland, flooding homes and cutting off escape routes. The storm surges and winds of hurricanes may be destructive to human-made structures, but they also stir up the waters of coastal estuaries, which are typically important fish breeding locales.

Heavy rainfall

The thunderstorm

Thunderstorm

A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...

activity in a tropical cyclone produces intense rain

Rain

fall, potentially resulting in flooding, mudslides, and landslides. Inland areas are particularly vulnerable to freshwater flooding, due to residents not preparing adequately. Heavy inland rainfall eventually flows into coastal estuaries, damaging marine life in coastal estuaries. The wet environment in the aftermath of a tropical cyclone, combined with the destruction of sanitation facilities and a warm tropical climate, can induce epidemics of disease which claim lives long after the storm passes. Infections of cuts and bruises can be greatly amplified by wading in sewage-polluted water. Large areas of standing water caused by flooding also contribute to mosquito-borne illnesses. Furthermore, crowded evacuees in shelters

Emergency shelter

Emergency shelters are places for people to live temporarily when they can't live in their previous residence, similar to homeless shelters. The main difference is that an emergency shelter typically specializes in people fleeing a specific type of situation, such as natural or man-made disasters,...

increase the risk of disease propagation.
Although cyclones take an enormous toll in lives and personal property, they may be important factors in the precipitation

Precipitation (meteorology)

In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...

regimes of places they affect and bring much-needed precipitation to otherwise dry regions. Hurricanes in the eastern north Pacific often supply moisture to the Southwestern United States

Southwestern United States

The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...

and parts of Mexico. Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

receives over half of its rainfall from typhoons. Hurricane Camille

Hurricane Camille

Hurricane Camille was the third and strongest tropical cyclone and second hurricane during the 1969 Atlantic hurricane season. The second of three catastrophic Category 5 hurricanes to make landfall in the United States during the 20th century , which it did near the mouth of the Mississippi River...

averted drought conditions and ended water deficits along much of its path, though it also killed 259 people and caused $9.14 billion (2005 USD) in damage.

On the other hand, the occurrence of tropical cyclones can cause tremendous variability in rainfall over the areas they effect: indeed cyclones are the primary cause of the most extreme rainfall variability in the world, observed in places such as Onslow

Onslow, Western Australia

Onslow is a coastal town in the Pilbara region of Western Australia, north of Perth. It currently has a population of around 573 people and is in the Shire of Ashburton Local Government Area....

and Port Hedland

Port Hedland, Western Australia

Port Hedland is the highest tonnage port in Australia and largest town in the Pilbara region of Western Australia, with a population of approximately 14,000 ....

in subtropical Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

where the annual rainfall can range from practically nothing with no cyclones to over 1000 millimetres (39.4 in) if cyclones are abundant.

Tornadoes

The broad rotation of a land falling tropical cyclone often spawns tornadoes

History of tropical cyclone-spawned tornadoes

Intense tropical cyclones usually produce tornadoes, the majority of them weak, especially upon landfall.- List of Atlantic tropical cyclones which spawned tornadoes :These are the Atlantic tropical cyclones that are known to have spawned tornadoes in the U.S....

, particularly in their right front quadrant. While these tornadoes are normally not as strong as their non-tropical counterparts, heavy damage or loss of life can still occur. Tornadoes can also be spawned
as a result of eyewall mesovortices, which persist until landfall.

Deaths

Deaths per year from tropical cyclones
Australia	5
United States	25
East Asia	740
Globally	10000

During the last two centuries, tropical cyclones have been responsible for the deaths of about 1.9 million persons worldwide. It is estimated that 10,000 people per year perish due to tropical cyclones. The deadliest tropical cyclone was the 1970 Bhola cyclone

1970 Bhola cyclone

The 1970 Bhola cyclone was a devastating tropical cyclone that struck East Pakistan and India's West Bengal on November 12, 1970. It was the deadliest tropical cyclone ever recorded, and one of the deadliest natural disasters in modern times...

, which had a death toll of anywhere from 300,000 to 500,000 lives.

United States

Before Hurricane Katrina

Hurricane Katrina

Hurricane Katrina of the 2005 Atlantic hurricane season was a powerful Atlantic hurricane. It is the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States. Among recorded Atlantic hurricanes, it was the sixth strongest overall...

, the average death rate for tropical cyclones in the United States was decreasing. The main cause of storm-related fatalities was shifting away from storm surge and towards freshwater flooding. However, the median

Median

In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to...

death rate per storm had increased through 1979, with a lull during the 1980-1995 period. This was due to greater numbers of people moving to the coastal margins and into harm's way. Despite advances in warning strategies and reduction in track forecast error, this increase in fatalities is expected to continue for as long as people migrate towards the shore.

Reconstruction and repopulation

While tropical cyclones may well seriously damage settlement, total destruction encourages rebuilding. For example, the destruction wrought by Hurricane Camille

Hurricane Camille

on the Gulf coast spurred redevelopment, greatly increasing local property values. However, disaster response officials point out that redevelopment encourages more people to live in clearly dangerous areas subject to future deadly storms. Hurricane Katrina

Hurricane Katrina

is the most obvious example, as it devastated the region that had been revitalized after Hurricane Camille. Many former residents and businesses do relocate to inland areas away from the threat of future hurricanes as well.

In isolated areas with small populations, tropical cyclones may cause enough casualties to contribute to the founder's effect as survivors repopulate their place. For example, around 1775, a typhoon hit Pingelap Atoll, and in combination with a subsequent famine, reduced the island's population to a low level. Several generations after the disaster, as many as 10% of Pingelapese have a genetic

Genetic disorder

A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....

form of color-blindness called achromatopsia

Achromatopsia

Achromatopsia , is a medical syndrome that exhibits symptoms relating to at least five separate individual disorders. Although the term may refer to acquired disorders such as color agnosia and cerebral achromatopsia, it typically refers to an autosomal recessive congenital color vision disorder,...

. This is due to one of the survivors of the depopulation brought on by the typhoon having a mutated gene, which the population bottleneck

Population bottleneck

A population bottleneck is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing....

caused to be at a higher-than-usual level in succeeding generations.

Geomorphology

Tropical cyclones reshape the geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

near the coast by eroding sand from the beach

Beach

A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

as well as offshore, rearranging coral, and changing dune configuration onshore. Their rain water gets absorbed into stalagmite

Stalagmite

A stalagmite is a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of calcium carbonate. This stalagmite formation occurs only under certain pH conditions within the underground cavern. The corresponding formation on...

s within caves, creating a record of past tropical cyclone impacts.

Coastal ridges

Waves and storm surges accompanying tropical cyclones erode undersea sands, erode shell deposits, break off corals from near shore reefs in their paths, and carry all this detritus landwards in a rolling wave of material that is deposited onshore, above highest astronomical tide

Tide

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....

as a ridge of sand, shell and coral. For example, each severe tropical cyclone (i.e. Category 4-5 on the Saffir-Simpson scale) crossing northeast Australia

Australia

's tropical coastline since the last significant change in sea levels (about 5000 years ago) has 'emplaced' such ridges within the coastal landscape forming, in some places, series of ridges and a geomorphological record of highest magnitude cyclones hitting the coast over 3000 – 5000 years.

Eyewitness accounts verify ridges of this kind are formed by severe tropical cyclones and two clear examples cited are the 18 kilometres (11.2 mi) long, 35 metres (114.8 ft) wide, 3.5 metres (11.5 ft) high coral shingle ridge deposited on Funafuti Atoll (Central South Pacific) by Tropical Cyclone Bebe in October 1971, and the large coral shingle ridge deposited on Jaluit Atoll (Marshall Islands

Marshall Islands

The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...

) by Typhoon Ophelia in January 1958. In tropical northeast Australia, an intense tropical cyclone hit in March 1918 (crossing over the town of Innisfail

Innisfail, Queensland

Innisfail is a town located in the far north of the state of Queensland, Australia. It is the major township of the Cassowary Coast and is well renowned for its sugar and banana industries, as well as for being one of Australia's wettest towns...

), at which time there were eyewitness accounts of a 4.5 metres (14.8 ft) to 5.1 metres (16.7 ft) high ridge of pumice being deposited by that cyclone's surge as it crossed the coast.).

Limestone cave stalagmites

When tropical cyclones cross land, thin layers of calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

of unusually 'light' Oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

isotope

Isotope

Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

(Oxygen-18) composition are deposited onto stalagmite

Stalagmite

s in limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

caves up to 300 kilometres (186.4 mi) from the cyclone's path.

As the cloud tops of tropical cyclones are high and cold, and their air is humid - their rainwater is 'lighter'. In other words, the rainfall contains significantly higher quantities of unevaporated Oxygen-18 than other tropical rainfall. The isotopically lighter rainwater soaks into the ground, percolates down into caves, and, within a couple of weeks, Oxygen-18 transfers from the water into calcium carbonate, before being deposited in thin layers or 'rings' within stalagmites. A succession of such events created within stalagmites maintain a record of cyclones tracking within a 300 kilometres (186.4 mi) radius of caves going back centuries, millennia, or even millions of years.

At Actun Tunichil Muknal cave in central Belize

Belize

Belize is a constitutional monarchy and the northernmost country in Central America. Belize has a diverse society, comprising many cultures and languages. Even though Kriol and Spanish are spoken among the population, Belize is the only country in Central America where English is the official...

, researchers drilling stalagmites with a computer- controlled dental drill accurately identified and verified evidence of isotopically light rainfall for 11 tropical cyclones occurring over a 23 year period (1978–2001).

At the Chillagoe limestone caves in northeast Australia (130 kilometres (80.8 mi) inland from Cairns) researchers identified and matched evidence of isotopically light rainfall with 100 years of cyclone records, and from this have created a record of tropical cyclones from 2004 back to 1200 A.D. (an 800 year record).

Landscapes

Severe tropical cyclones defoliate tropical forest canopy trees, remove vine

Vine

A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...

s and epiphytes from the trees, break tree crown stems, and cause tree falls. The degree of damage they do along their paths, at a landscape level (i.e. > 10 kilometres (6.2 mi)), can be catastrophic yet variable and patchy. Stripping trees and scattering forest debris also provides fuel for wildfire

Wildfire

A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...

s, such as a blaze that lasted three months in 1989 and burned 460 square miles (1,191.4 km²) of forest that had been stripped by Hurricane Gilbert

Hurricane Gilbert

Hurricane Gilbert was an extremely powerful Cape Verde-type hurricane that formed during the 1988 Atlantic hurricane season and created widespread destruction in the Caribbean Sea and the Gulf of Mexico. It is the second most intense hurricane ever observed in the Atlantic basin behind only...

Wind velocity gradients or horizontal wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...

(size of cyclone, the intensity of cyclone, proximity to the cyclone, and local scale cyclonic convection effects).

Degree of exposure (windward exposure, leeward acceleration, or local topographic sheltering/shading); and

Ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

species composition and forest structure

Assessments of cyclone damage done to tropical rainforest landscapes in northeast Australia

Australia

, have produced the following typology

Typology

Typology is the study of types. More specifically, it may refer to:*Typology , division of culture by races*Typology , classification of things according to their characteristics...

for describing and 'mapping' the variable impacts they have along their paths, as follows:

Severe and extensive closest to the centre of cyclone: impact appears to be multidirectional and is evidenced by crowns of most trees having been broken, smashed or windthrown
Severe and localised closer to the cyclone centre than its edge: direction of the destructive winds is clearly identifiable, and severe canopy disruption is limited to the windward aspect of these forested areas
Moderate canopy disturbance closer to cyclone edge than its centre: most of the tree stems are still standing, with only some treefalls, and most of the damage is the defoliation of the canopy and branch breakage;
Slight canopy disturbance closest to cyclone edge: occasional stem fall or branch breakage, with most of the damage consisting of loss of foliage on the forest edges only, subsequently followed by leaf damage and heavy leaf litter falls.

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.