Storms have the potential to harm lives and property viastorm surge, heavy rain or snow causing flooding or road impassibility,lightning,wildfires, and vertical and horizontalwind shear. Systems with significant rainfall and duration help alleviate drought in places they move through. Heavy snowfall can allow special recreational activities to take place which would not be possible otherwise, such as skiing and snowmobiling.
The English word comes fromProto-Germanicsturmaz meaning "noise, tumult";[2] a synonym istempest, of French origin.
Storms are created when a center oflow pressure develops with the system ofhigh pressure surrounding it. This combination of opposing forces can create winds and result in the formation of stormclouds such ascumulonimbus. Small localized areas of low pressure can form from hot air rising off hot ground, resulting in smaller disturbances such asdust devils andwhirlwinds.
Blizzard – There are varying definitions for blizzards, both over time and by location. In general, a blizzard is accompanied bygale-force winds, heavy snow (accumulating at a rate of at least 5 centimeters (2 in) per hour), and very cold conditions (below approximately −10 degrees Celsius or 14 F). Lately, the temperature criterion has fallen out of the definition across the United States.[3]
Bomb cyclone – A rapid deepening of a mid-latitude cyclonic low-pressure area, typically occurring over the ocean, but can occur over land. The winds experienced during these storms can be as powerful as that of a typhoon or hurricane.
Derecho – A derecho is a widespread, long-lived, straight-line wind storm that is associated with a land-based, fast-moving group of severe thunderstorms.
Dust devil – A small, localized updraft of rising air.
Dust storm – A situation in which winds pick up large quantities of sand or soil, greatly reducingvisibility.
Firestorm – Firestorms are conflagrations which attain such intensity that they create and sustain their own wind systems. It is most commonly a natural phenomenon, created during some of the largest bush fires, forest fires, and wildfires. ThePeshtigo Fire is one example of a firestorm. Firestorms can also be deliberate effects of targeted explosives, such as occurred as a result of the aerialbombings of Dresden.Nuclear detonations generate firestorms if high winds are not present.
Hailstorm – A type of storm that precipitates round chunks of ice. Hailstorms usually occur during regular thunderstorms. While most of the hail that precipitates from the clouds is fairly small and virtually harmless, there are occasional occurrences of hail greater than 2 inches (5 cm) in diameter that can cause much damage and injuries.
Ice storm – [6] Ice storms are one of the most dangerous forms ofwinter storms. When surface temperatures are below freezing, but a thick layer of above-freezing air remains aloft, rain can fall into the freezing layer and freeze upon impact into a glaze of ice. In general, 8 millimetres (0.31 in) of accumulation is all that is required, especially in combination with breezy conditions, to start downing power lines as well as tree limbs.[7] Ice storms also make unheated road surfaces too slick to drive upon. Ice storms can vary in time range from hours to days and can cripple small towns and large metropolitan cities alike.
Microburst – A very powerful windstorm produced during a thunderstorm that only lasts a few minutes.
Ocean Storm or sea storm – Storm conditions out at sea are defined as having sustained winds of 48 knots (55 mph or 90 km/h) or greater.[5] Usually just referred to as a storm, these systems can sink vessels of all types and sizes.
Snowstorm – A heavy fall of snow accumulating at a rate of more than 5 centimeters (2 in) per hour that lasts several hours. Snow storms, especially ones with a high liquid equivalent and breezy conditions, can down tree limbs, cut off power connections and paralyze travel over large regions.
Squall – Sudden onset of wind increase of at least 16 knots (30 km/h) or greater sustained for at least one minute.
Thunderstorm – A thunderstorm is a type of storm that generates bothlightning andthunder. It is normally accompanied by heavyprecipitation. Thunderstorms occur throughout the world, with the highest frequency in tropicalrainforest regions where there are conditions of high humidity and temperature along with atmospheric instability. These storms occur when high levels of condensation form in a volume of unstable air that generates deep, rapid, upward motion in the atmosphere. The heat energy creates powerful rising air currents that swirl upwards to thetropopause. Cool descending air currents produce strong downdraughts below the storm. After the storm has spent its energy, the rising currents die away and downdraughts break up the cloud. Individual storm clouds can measure 2–10 km across.
Tornado – A tornado is a violent, destructive whirlwind storm occurring on land. Usually its appearance is that of a dark, funnel-shaped cloud. Often tornadoes are preceded by or associated with thunderstorms and awall cloud. They are often called the most destructive of storms, and while they form all over the planet, the interior of the United States is the most prone area, especially throughoutTornado Alley.
Tropical cyclone – A tropical cyclone is a storm system with a closed circulation around a centre oflow pressure, fueled by the heat released when moist air rises and condenses. The name underscores its origin in the tropics and theircyclonic nature. Tropical cyclones are distinguished from other cyclonic storms such asnor'easters andpolar lows by the heat mechanism that fuels them, which makes them "warm core" storm systems. Tropical cyclones form in the oceans if theconditions in the area are favorable, and depending on their strength and location, there are various terms by which they are called, such astropical depression,tropical storm,hurricane andtyphoon.[8]
Wind storm – A storm marked by high wind with little or no precipitation.[9] Windstorm damage often opens the door for massive amounts of water and debris to cause further damage to a structure.[10]European windstorms andderechos are two type of windstorms.[11] High wind is also the cause ofsandstorms in dry climates.
Classification
A strictmeteorological definition of a terrestrial storm is a wind measuring 10 or higher on theBeaufort scale, meaning a wind speed of 24.5m/s (89 km/h, 55 mph) or more; however, popular usage is not so restrictive. Storms can last anywhere from 12 to 200 hours, depending on season and geography. In North America, the east and northeast storms are noted for the most frequent repeatability and duration, especially during the cold period. Big terrestrial storms alter theoceanographic conditions that in turn may affect food abundance and distribution: strong currents, strong tides, increased siltation, change in water temperatures, overturn in the water column, etc.
Storms do not only occur on Earth; other planetary bodies with a sufficient atmosphere (giant planets in particular) also undergo stormy weather. TheGreat Red Spot onJupiter provides a well-known example.[12] Though technically an anticyclone, with greater than hurricane wind speeds, it is larger than the Earth and has persisted for at least 340 years, having first been observed by astronomerGiovanni Domenico Cassini.Neptune also had its own lesser-knownGreat Dark Spot.
The dust storms ofMars vary in size, but can often cover the entire planet. They tend to occur when Mars comes closest to the Sun, and have been shown to increase the global temperature.[14]
One particularly large Martian storm was exhaustively studied up close due to coincidental timing. When the firstspacecraft to successfully orbit another planet,Mariner 9, arrived and successfully orbited Mars on 14 November 1971,planetary scientists were surprised to find theatmosphere was thick with a planet-wide robe ofdust, the largest storm ever observed on Mars. The surface of the planet was totally obscured. Mariner 9's computer was reprogrammed from Earth to delay imaging of the surface for a couple of months until the dust settled, however, the surface-obscured images contributed much to the collection of Mars atmospheric and planetary surface science.[15]
Twoextrasolar planets are known to have storms:HD 209458 b[16] andHD 80606 b. The former's storm was discovered on 23 June 2010, and measured at 6,200 km/h (3,900 mph), while the latter produces winds of 17,700 km/h (11,000 mph) across the surface. The spin of the planet then creates giant swirling shock-wave storms that carry the heat aloft.[17]
Effects on human society
"Storm damage" redirects here. For the British television film, seeStorm Damage.
A snow blockade in southern Minnesota in 1881A return stroke, cloud-to-groundlightning strike during athunderstorm.Asunshower storm in theMojave Desert at sunset.A lightning strike during a desert storm at twilight
Shipwrecks are common with the passage of strong tropical cyclones. Such shipwrecks can change the course of history,[18] 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.[19]Strong winds from any storm type can damage or destroy vehicles, buildings, bridges, and other outside objects, turning loose debris into deadly flying projectiles. In the United States,major hurricanes comprise just 21% of all landfalling tropical cyclones, but account for 83% of all damage.[20] Tropical cyclones often knock out power to tens or hundreds of thousands of people, preventing vital communication and hampering rescue efforts.[21] 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 adiaspora of the population of the region.[22]
Thestorm 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.[22] 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.
Cloud-to-ground lightning frequently occurs within the phenomena of thunderstorms and have numerous hazards towards landscapes and populations. One of the more significant hazards lightning can pose is the wildfires they are capable of igniting.[23] Under a regime of low precipitation (LP) thunderstorms, where little precipitation is present, rainfall cannot prevent fires from starting when vegetation is dry as lightning produces a concentrated amount of extreme heat.[24] Wildfires can devastate vegetation and the biodiversity of an ecosystem. Wildfires that occur close to urban environments can inflict damages upon infrastructures, buildings, crops, and provide risks to explosions, should the flames be exposed to gas pipes. Direct damage caused by lightning strikes occurs on occasion.[25] In areas with a high frequency for cloud-to-ground lightning, like Florida, lightning causes several fatalities per year, most commonly to people working outside.[26]
Precipitation with lowpotential of hydrogen levels (pH), otherwise known as acid rain, is also a frequent risk produced by lightning.Distilled water, which contains nocarbon dioxide, has aneutralpH of 7. Liquids with a pH less than 7 are acidic, and those with a pH greater than 7 are bases. "Clean" or unpolluted rain has a slightly acidic pH of about 5.2, because carbon dioxide and water in the air react together to formcarbonic acid, a weak acid (pH 5.6 in distilled water), but unpolluted rain also contains other chemicals.[27]Nitric oxide present during thunderstorm phenomena,[28] caused by the splitting of nitrogen molecules, can result in the production of acid rain, if nitric oxide forms compounds with the water molecules in precipitation, thus creating acid rain. Acid rain can damage infrastructures containing calcite or other solid chemical compounds containing carbon. In ecosystems, acid rain can dissolve plant tissues of vegetations and increase acidification process in bodies of water and insoil, resulting in deaths of marine and terrestrial organisms.[29]
Hail damage to roofs often goes unnoticed until further structural damage is seen, such as leaks or cracks. It is hardest to recognize hail damage on shingled roofs and flat roofs, but all roofs have their own hail damage detection problems.[30] Metal roofs are fairly resistant to hail damage, but may accumulate cosmetic damage in the form of dents and damaged coatings. Hail is also a common nuisance to drivers of automobiles, severely denting the vehicle and cracking or even shatteringwindshields andwindows. Rarely, massive hailstones have been known to causeconcussions or fatal headtrauma. Hailstorms have been the cause of costly and deadly events throughout history. One of the earliest recorded incidents occurred around the 9th century inRoopkund, Uttarakhand, India.[31] The largest hailstone in terms of diameter and weight ever recorded in the United States fell on 23 July 2010, inVivian, South Dakota in the United States; it measured 8 inches (20 cm) in diameter and 18.62 inches (47.3 cm) in circumference, weighing in at 1.93 pounds (0.88 kg).[32] This broke the previous record for diameter set by a hailstone 7 inches (18 cm) diameter and 18.75 inches (47.6 cm) circumference which fell inAurora, Nebraska in the United States on 22 June 2003, as well as the record for weight, set by a hailstone of 1.67 pounds (0.76 kg) that fell inCoffeyville, Kansas in 1970.[32]
Various hazards, ranging from hail to lightning can affect outside technology facilities, such asantennas,satellite dishes, and towers. As a result, companies with outside facilities have begun installing such facilities underground, to reduce the risk of damage from storms.[33]
Substantial snowfall can disrupt public infrastructure and services, slowing human activity even in regions that are accustomed to such weather. Air and ground transport may be greatly inhibited or shut down entirely. Populations living in snow-prone areas have developed various ways to travel across the snow, such asskis,snowshoes, andsleds pulled by horses, dogs, or other animals and later,snowmobiles. Basic utilities such aselectricity,telephone lines, andgas supply can also fail. In addition, snow can make roads much harder to travel and vehicles attempting to use them can easily become stuck.[34]
The combined effects can lead to a "snow day" on which gatherings such as school, work, or church are officially canceled. In areas that normally have very little or no snow, a snow day may occur when there is only light accumulation or even the threat of snowfall, since those areas are unprepared to handle any amount of snow. In some areas, such as some states in the United States, schools are given a yearly quota of snow days (or "calamity days"). Once the quota is exceeded, the snow days must be made up.[35][36][37] In other states, all snow days must be made up.[38] For example, schools may extend the remaining school days later into the afternoon, shortenspring break, or delay the start ofsummer vacation.
Accumulated snow isremoved to make travel easier and safer, and to decrease the long-term effect of a heavy snowfall. This process usesshovels andsnowplows, and is often assisted by sprinkling salt or other chloride-based chemicals, which reduce the melting temperature of snow.[39] In some areas with abundant snowfall, such asYamagata Prefecture, Japan, people harvest snow and store it surrounded byinsulation in ice houses. This allows the snow to be used through the summer for refrigeration and air conditioning, which requires far less electricity than traditional cooling methods.[40]
Agriculture
Hail can cause serious damage, notably toautomobiles, aircraft, skylights, glass-roofed structures, livestock, and most commonly, farmers'crops.[41] Wheat, corn, soybeans, and tobacco are the most sensitive crops to hail damage.[42] Hail is one of Canada's most expensive hazards.[43] Snowfall can be beneficial to agriculture by serving as athermal insulator, conserving the heat of the Earth and protectingcrops from subfreezing weather. Some agricultural areas depend on an accumulation of snow during winter that will melt gradually in spring, providing water for crop growth. If it melts into water and refreezes upon sensitive crops, such as oranges, the resulting ice will protect the fruit from exposure to lower temperatures.[44] Although tropicalcyclones take an enormous toll in lives and personal property, they may be important factors in theprecipitation 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 and parts of Mexico.[45] Japan receives over half of its rainfall from typhoons.[46]Hurricane Camille averted drought conditions and ended water deficits along much of its path,[47] though it also killed 259 people and caused $9.14 billion (2005 USD) in damage.
Aviation
Effect of wind shear on aircraft trajectory. Merely correcting for the initial gust front can have dire consequences.
Hail is one of the most significant thunderstorm hazards to aircraft.[48] When hail stones exceed 0.5 inches (13 mm) in diameter, planes can be seriously damaged within seconds.[49] The hailstones accumulating on the ground can also be hazardous to landing aircraft. Strong wind outflow from thunderstorms causes rapid changes in the three-dimensional wind velocity just above ground level. Initially, this outflow causes a headwind that increases airspeed, which normally causes a pilot to reduce engine power if they are unaware of the wind shear. As the aircraft passes into the region of the downdraft, the localized headwind diminishes, reducing the aircraft's airspeed and increasing its sink rate. Then, when the aircraft passes through the other side of the downdraft, the headwind becomes a tailwind, reducing lift generated by the wings, and leaving the aircraft in a low-power, low-speed descent. This can lead to an accident if the aircraft is too low to effect a recovery before ground contact. As the result of the accidents in the 1970s and 1980s, in 1988 the U.S.Federal Aviation Administration mandated that all commercial aircraft haveon-board wind shear detection systems by 1993. Between 1964 and 1985, wind shear directly caused or contributed to 26 major civil transport aircraft accidents in the U.S. that led to 620 deaths and 200 injuries. Since 1995, the number of major civil aircraft accidents caused by wind shear has dropped to approximately one every ten years, due to the mandated on-board detection as well as the addition of Dopplerweather radar units on the ground. (NEXRAD)[50]
Recreation
Manywinter sports, such asskiing,[51]snowboarding,[52]snowmobiling,[53] andsnowshoeing depend upon snow. Where snow is scarce but the temperature is low enough,snow cannons may be used to produce an adequate amount for such sports.[54] Children and adults can play on asled or ride in asleigh. Although a person's footsteps remain a visiblelifeline within a snow-covered landscape, snow cover is considered a general danger to hiking since the snow obscures landmarks and makes the landscape itself appear uniform.[55]
According to the Bible, a giant storm sent by God flooded the Earth.Noah and his family and the animals enteredthe Ark, and "the same day were all the fountains of the great deep broken up, and the windows of heaven were opened, and the rain was upon the earth forty days and forty nights." The flood covered even the highest mountains to a depth of more than twenty feet, and all creatures died; only Noah and those with him on the Ark were left alive. In theNew Testament,Jesus Christ is recorded to have calmed a storm on theSea of Galilee.
TheSea Venture was wrecked nearBermuda in 1609, which led to the colonization of Bermuda[56] and provided the inspiration forShakespeare's playThe Tempest (1611).[57] Specifically,Sir Thomas Gates, future governor ofVirginia, was on his way to England fromJamestown, Virginia. OnSaint James Day, while he was betweenCuba and theBahamas, a hurricane raged for nearly two days. Though one of the small vessels in the fleet sank to the bottom of theFlorida Straits, seven of the remaining vessels reachedVirginia within several days after the storm. The flagship of the fleet, known asSea Adventure, disappeared and was presumed lost. A small bit of fortune befell the ship and her crew when they made landfall on Bermuda. The vessel was damaged on a surroundingcoral reef, but all aboard survived for nearly a year on the island. The British colonists claimed the island and quickly settled Bermuda. In May 1610, they set forth for Jamestown, this time arriving at their destination.
The children's novelThe Wonderful Wizard of Oz, written byL. Frank Baum and illustrated byW. W. Denslow, chronicles the adventures of a young girl namedDorothy Gale in theLand of Oz, after being swept away from her Kansas farm home by a tornado. The story was originally published by the George M. Hill Company in Chicago on 17 May 1900, and has since been reprinted numerous times, most often under the nameThe Wizard of Oz, and adapted for use in other media. Thanks in part to the1939 MGM movie, it is one of the best-known stories in American popular culture and has been widely translated. Its initial success, and the success of the popular1902 Broadway musical which Baum adapted from his original story, led to Baum's writing thirteen moreOz books.
Hollywood directorKing Vidor (8 February 1894 – 1 November 1982) survived theGalveston Hurricane of 1900 as a boy. Based on that experience, he published a fictionalized account of that cyclone, titled "Southern Storm", for the May 1935 issue ofEsquire magazine.Erik Larson excerpts a passage from that article in his 2005 book,Isaac's Storm:[58]
I remember now that it seemed as if we were in a bowl looking up toward the level of the sea. As we stood there in the sandy street, my mother and I, I wanted to take my mother's hand and hurry her away. I felt as if the sea was going to break over the edge of the bowl and come puring down upon us.
Numerous other accounts of the Galveston Hurricane of 1900 have been made in print and in film. Larson cites many of them inIsaac's Storm, which centrally features that storm, as well as chronicles the creation of the Weather Bureau (which came to known as theNational Weather Service) and that agency's fateful rivalry with the weather service in Cuba, and a number of other major storms, such as those which ravagedIndianola, Texas in 1875 and1886.[58]
TheGreat Storm of 1987 is key in an important scene near the end ofPossession: A Romance, the bestselling andBooker Prize-winning novel byA. S. Byatt. The Great Storm of 1987 occurred on the night of 15–16 October 1987, when an unusually strong weather system caused winds to hit much ofsouthern England and northern France. It was the worst storm to hit England since theGreat Storm of 1703[59] (284 years earlier) and was responsible for the deaths of at least 22 people in England and France combined (18 in England, at least four in France).[60]
Hurricane Katrina (2005) has been featured in a number of works of fiction.
The Romantic seascape paintersJ. M. W. Turner andIvan Aivazovsky created some of the most lasting impressions of the sublime and stormy seas that are firmly imprinted on the popular mind. Turner's representations of powerful natural forces reinvented the traditionalseascape during the first half of the nineteenth century.
Upon his travels to Holland, he took note of the familiar large rolling waves of the English seashore transforming into the sharper,choppy waves of a Dutch storm. A characteristic example of Turner's dramatic seascape isThe Slave Ship of 1840. Aivazovsky left several thousand turbulent canvases in which he increasingly eliminated human figures and historical background to focus on such essential elements as light, sea, and sky. His grandioseNinth Wave (1850) is an ode to human daring in the face of the elements.
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