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A storm is any disturbed state of an environment or in an astronomical body's atmosphere especially affecting its surface, and strongly implying severe weather. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning (a thunderstorm), heavy precipitation (snowstorm, rainstorm), heavy freezing rain (ice storm), strong winds (tropical cyclone, windstorm), or wind transporting some substance through the atmosphere as in a dust storm, blizzard, sandstorm, etc.
The natural environment encompasses all living and non-living things occurring naturally, meaning in this case not artificial. The term is most often applied to the Earth or some parts of Earth. This environment encompasses the interaction of all living species, climate, weather and natural resources that affect human survival and economic activity. The concept of the natural environment can be distinguished as components:
Severe weather refers to any dangerous meteorological phenomena with the potential to cause damage, serious social disruption, or loss of human life. Types of severe weather phenomena vary, depending on the latitude, altitude, topography, and atmospheric conditions. High winds, hail, excessive precipitation, and wildfires are forms and effects of severe weather, as are thunderstorms, downbursts, tornadoes, waterspouts, tropical cyclones, and extratropical cyclones. Regional and seasonal severe weather phenomena include blizzards (snowstorms), ice storms, and duststorms.
Wind is the flow of gases on a large scale. On the surface of the 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. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect. The strongest observed winds on a planet in the Solar System occur on Neptune and Saturn. Winds have various aspects, an important one being its velocity ; another the density of the gas involved; another its energy content or wind energy. Wind is also a great source of transportation for seeds and small birds; with time things can travel thousands of miles in the wind.
Storms have the potential to harm lives and property via storm surge, heavy rain or snow causing flooding or road impassibility, lightning, wildfires, and vertical wind 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.
A storm surge, storm flood, tidal surge or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low pressure weather systems, the severity of which is affected by the shallowness and orientation of the water body relative to storm path, as well as the timing of tides. Most casualties during tropical cyclones occur as the result of storm surges. It is a measure of the rise of water beyond what would be expected by the normal movement related to tides.
Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystems, as well as water for hydroelectric power plants and crop irrigation.
Snow refers to forms of ice crystals that precipitate from the atmosphere and undergo changes on the Earth's surface. It pertains to frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide or sublimate away. Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and rime. As snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering, sublimation and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form. Otherwise, snow typically melts seasonally, causing runoff into streams and rivers and recharging groundwater.
The English word comes from Proto-Germanic *sturmaz meaning "noise, tumult".
English is a West Germanic language that was first spoken in early medieval England and eventually became a global lingua franca. It is named after the Angles, one of the Germanic tribes that migrated to the area of Great Britain that later took their name, as England. Both names derive from Anglia, a peninsula in the Baltic Sea. The language is closely related to Frisian and Low Saxon, and its vocabulary has been significantly influenced by other Germanic languages, particularly Norse, and to a greater extent by Latin and French.
Storms are created when a center of low pressure develops with the system of high pressure surrounding it. This combination of opposing forces can create winds and result in the formation of storm clouds such as cumulonimbus. Small localized areas of low pressure can form from hot air rising off hot ground, resulting in smaller disturbances such as dust devils and whirlwinds.
Cumulonimbus is a dense, towering vertical cloud, forming from water vapor carried by powerful upward air currents. If observed during a storm, these clouds may be referred to as thunderheads. Cumulonimbus can form alone, in clusters, or along cold front squall lines. These clouds are capable of producing lightning and other dangerous severe weather, such as tornadoes. Cumulonimbus progress from overdeveloped cumulus congestus clouds and may further develop as part of a supercell. Cumulonimbus is abbreviated Cb.
There are many varieties and names for storms:
A blizzard is a severe snowstorm characterized by strong sustained winds of at least 56 km/h (35 mph) and lasting for a prolonged period of time—typically three hours or more. A ground blizzard is a weather condition where snow is not falling but loose snow on the ground is lifted and blown by strong winds. Blizzards can have an immense size and usually stretch to hundreds or thousands of kilometres.
A gale is a strong wind, typically used as a descriptor in nautical contexts. The U.S. National Weather Service defines a gale as 34–47 knots of sustained surface winds. Forecasters typically issue gale warnings when winds of this strength are expected. In the United States, a gale warning is specifically a maritime warning; the land-based equivalent in National Weather Service warning products is a wind advisory.
Explosive cyclogenesis is the rapid deepening of an extratropical cyclonic low-pressure area. The change in pressure needed to classify something as explosive cyclogenesis is latitude dependent. For example, at 60° latitude, explosive cyclogenesis occurs if the central pressure decreases by 24 mbar (hPa) or more in 24 hours. This is a predominantly maritime, winter event, but also occurs in continental settings, even in the summer. This process is the extratropical equivalent of the tropical rapid deepening. Although their cyclogenesis is totally different from that of tropical cyclones, bombs can produce winds of 74–95 mph, the same order as the first categories of the Saffir-Simpson scale and give heavy precipitation. Even though only a minority of the bombs become so strong, some have caused significant damage.
A strict meteorological definition of a terrestrial storm is a wind measuring 10 or higher on the Beaufort scale, meaning a wind speed of 24.5 m/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 the oceanographic 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.
Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data. It was not until after the elucidation of the laws of physics and more particularly, the development of the computer, allowing for the automated solution of a great many equations that model the weather, in the latter half of the 20th century that significant breakthroughs in weather forecasting were achieved. An important domain of weather forecasting is marine weather forecasting as it relates to maritime and coastal safety, in which weather effects also include atmospheric interactions with large bodies of water.
The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale.
The metre per second is an SI derived unit of both speed (scalar) and velocity, defined by distance in metres divided by time in seconds.
Storms do not only occur on Earth; other planetary bodies with a sufficient atmosphere (gas giants in particular) also undergo stormy weather. The Great Red Spot on Jupiter provides a well-known example. 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 astronomer Galileo Galilei. Neptune also had its own lesser-known Great Dark Spot.
In September 1994, the Hubble telescope – using Wide Field Planetary Camera 2 – imaged storms on Saturn generated by upwelling of warmer air, similar to a terrestrial thunderhead. The east-west extent of the same-year[ clarification needed ] storm equalled the diameter of Earth. The storm was observed earlier in September 1990 and acquired the name Dragon Storm.
The dust storms of Mars 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.
One particularly large Martian storm was exhaustively studied up close due to coincidental timing. When the first spacecraft to successfully orbit another planet, Mariner 9, arrived and successfully orbited Mars on 14 November 1971, planetary scientists were surprised to find the atmosphere was thick with a planet-wide robe of dust, 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.
Two extrasolar planets are known to have storms: HD 209458 b km/h, while the latter produces winds of 17,700 kilometers (11,000 mi) per hour across the surface. The spin of the planet then creates giant swirling shock-wave storms that carry the heat aloft.and HD 80606 b. The former's storm was discovered on June 23, 2010 and measured at 6,200
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.
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.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 of the population of the region.
The 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.
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.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. 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. 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.
Precipitation with low potential of hydrogen levels (pH), otherwise known as acid rain, is also a frequent risk produced by lightning. Distilled water, which contains no carbon dioxide, has a neutral pH 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 form carbonic acid, a weak acid (pH 5.6 in distilled water), but unpolluted rain also contains other chemicals.Nitric oxide present during thunderstorm phenomena, 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 in soil, resulting in deaths of marine and terrestrial organisms.
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. 8 inches (20 cm) in diameter and 18.62 inches (47.3 cm) in circumference, weighing in at 1.93 pounds (0.88 kg). This broke the previous record for diameter set by a hailstone 7 inches diameter and 18.75 inches circumference which fell in Aurora, Nebraska in the United States on June 22, 2003, as well as the record for weight, set by a hailstone of 1.67 pounds (0.76 kg) that fell in Coffeyville, Kansas in 1970.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 shattering windshields and windows. Rarely, massive hailstones have been known to cause concussions or fatal head trauma. Hailstorms have been the cause of costly and deadly events throughout history. One of the earliest recorded incidents occurred around the 9th century in Roopkund, Uttarakhand, India. The largest hailstone in terms of diameter and weight ever recorded in the United States fell on July 23, 2010 in Vivian, South Dakota in the United States; it measured
Various hazards, ranging from hail to lightning can affect outside technology facilities, such as antennas, satellite dishes, and towers. As a result, companies with outside facilities have begun installing such facilities underground, in order to reduce the risk of damage from storms.
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 as skis, snowshoes, and sleds pulled by horses, dogs, or other animals and later, snowmobiles. Basic utilities such as electricity, telephone lines, and gas supply can also fail. In addition, snow can make roads much harder to travel and vehicles attempting to use them can easily become stuck.
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.In other states, all snow days must be made up. For example, schools may extend the remaining school days later into the afternoon, shorten spring break, or delay the start of summer vacation.
Accumulated snow is removed to make travel easier and safer, and to decrease the long-term effect of a heavy snowfall. This process utilizes shovels and snowplows, and is often assisted by sprinkling salt or other chloride-based chemicals, which reduce the melting temperature of snow.In some areas with abundant snowfall, such as Yamagata Prefecture, Japan, people harvest snow and store it surrounded by insulation 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.
Hail can cause serious damage, notably to automobiles, aircraft, skylights, glass-roofed structures, livestock, and most commonly, farmers' crops. people and caused $9.14 billion (2005 USD) in damage.Wheat, corn, soybeans, and tobacco are the most sensitive crops to hail damage. Hail is one of Canada's most expensive hazards. Snowfall can be beneficial to agriculture by serving as a thermal insulator, conserving the heat of the Earth and protecting crops 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. Although tropical cyclones take an enormous toll in lives and personal property, they may be important factors in the 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 and parts of Mexico. Japan receives over half of its rainfall from typhoons. Hurricane Camille averted drought conditions and ended water deficits along much of its path, though it also killed 259
Hail is one of the most significant thunderstorm hazards to aircraft. 0.5 inches (13 mm) in diameter, planes can be seriously damaged within seconds. 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 have on-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 Doppler weather radar units on the ground. (NEXRAD)When hail stones exceed
Many winter sports, such as skiing,snowboarding, snowmobiling, and snowshoeing 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. Children and adults can play on a sled or ride in a sleigh. Although a person's footsteps remain a visible lifeline 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.
According to the Bible, a giant storm sent by God flooded the Earth. Noah and his family and the animals entered the 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 the New Testament, Jesus Christ is recorded to have calmed a storm on the Sea of Galilee.
The Gilgamesh flood myth is a deluge story in the Epic of Gilgamesh .
In Greek mythology Aeolus, keeper of storm-winds, squalls and tempests.
The Sea Venture was wrecked near Bermuda in 1609, which led to the colonization of Bermudaand provided the inspiration for Shakespeare's play The Tempest (1611). Specifically, Sir Thomas Gates, future governor of Virginia, was on his way to England from Jamestown, Virginia. On Saint James Day, while he was between Cuba and the Bahamas, a hurricane raged for nearly two days. Though one of the small vessels in the fleet sank to the bottom of the Florida Straits, seven of the remaining vessels reached Virginia within several days after the storm. The flagship of the fleet, known as Sea 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 surrounding coral 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 novel The Wonderful Wizard of Oz , written by L. Frank Baum and illustrated by W. W. Denslow, chronicles the adventures of a young girl named Dorothy Gale in the Land 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 May 17, 1900 and has since been reprinted numerous times, most often under the name The Wizard of Oz, and adapted for use in other media. Thanks in part to the 1939 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 popular 1902 Broadway musical which Baum adapted from his original story, led to Baum's writing thirteen more Oz books.
Hollywood director King Vidor (February 8, 1894 – November 1, 1982) survived the Galveston 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 of Esquire magazine. Erik Larson excerpts a passage from that article in his 2005 book, Isaac's Storm :
Numerous other accounts of the Galveston Hurricane of 1900 have been made in print and in film. Larson cites many of them in Isaac's Storm , which centrally features that storm, as well as chronicles the creation of the Weather Bureau (which came to known as the National 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 ravaged Indianola, Texas in 1875 and 1886.
The Great Storm of 1987 is key in an important scene near the end of Possession: A Romance , the bestselling and Man Booker Prize-winning novel by A. S. Byatt. The Great Storm of 1987 occurred on the night of October 15–16, 1987, when an unusually strong weather system caused winds to hit much of southern England and northern France. It was the worst storm to hit England since the Great Storm of 1703 people in England and France combined (18 in England, at least four in France).(284 years earlier) and was responsible for the deaths of at least 22
Hurricane Katrina (2005) has been featured in a number of works of fiction.
The Romantic seascape painters J. M. W. Turner and Ivan 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 traditional seascape 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 is The 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 grandiose Ninth Wave (1850) is an ode to human daring in the face of the elements.
The 1926 silent film The Johnstown Flood features the Great Flood of 1889 in Johnstown, Pennsylvania. The flood, caused by the catastrophic failure of the South Fork Dam after days of extremely heavy rainfall, prompted the first major disaster relief effort by the American Red Cross, directed by Clara Barton. The Johnstown Flood was depicted in numerous other media (both fictional and in non-fiction), as well.
Warner Bros.' 2000 dramatic disaster film The Perfect Storm , directed by Wolfgang Petersen, is an adaptation of Sebastian Junger's 1997 non-fiction book of the same title. The book and film feature the crew of the Andrea Gail , which got caught in the Perfect Storm of 1991. The 1991 Perfect Storm, also known as the Halloween Nor'easter of 1991, was a nor'easter that absorbed Hurricane Grace and ultimately evolved into a small hurricane late in its life cycle.
Storms have also been portrayed in many works of music. Examples of storm music include Vivaldi's Four Seasons violin concerto RV 315 (Summer) (third movement: Presto), Beethoven's Pastoral Symphony (the fourth movement), a scene in Act II of Rossini's opera The Barber of Seville , the third act of Giuseppe Verdi's Rigoletto, and the fifth (Cloudburst) movement of Ferde Grofé's Grand Canyon Suite.
Hail is a form of solid precipitation. It is distinct from ice pellets, though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets fall generally in cold weather while hail growth is greatly inhibited during cold surface temperatures.
In meteorology, a cyclone is a large scale air mass that rotates around a strong center of low atmospheric pressure. Cyclones are characterized by inward spiraling winds that rotate about a zone of low pressure. The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale. Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale. Mesocyclones, tornadoes, and dust devils lie within smaller mesoscale. Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the tropical upper tropospheric trough during the summer months in the Northern Hemisphere. Cyclones have also been seen on extraterrestrial planets, such as Mars, Jupiter, and Neptune. Cyclogenesis is the process of cyclone formation and intensification. Extratropical cyclones begin as waves in large regions of enhanced mid-latitude temperature contrasts called baroclinic zones. These zones contract and form weather fronts as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones occlude as cold air masses undercut the warmer air and become cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical jet stream.
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in a type of cloud known as a cumulonimbus. They are usually accompanied by strong winds, and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms produce little precipitation or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a right angle to the wind shear direction.
In meteorology, precipitation is any product of the condensation of atmospheric water vapour that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, snow, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and "precipitates". Thus, fog and mist are not precipitation but suspensions, because the water vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called "showers."
Thundersnow, also known as a winter thunderstorm or a thundersnowstorm, is an unusual kind of thunderstorm with snow falling as the primary precipitation instead of rain. It typically falls in regions of strong upward motion within the cold sector of an extratropical cyclone. Thermodynamically, it is not different from any other type of thunderstorm, but the top of the cumulonimbus cloud is usually quite low. In addition to snow, graupel or hail may fall.
This is a list of meteorology topics. The terms relate to meteorology, the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting.
This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United States Department of Commerce (DoC), defines precise meanings for nearly all of its weather terms. This article describes NWS terminology and related weather scales used by the agency. Some terms may be specific to certain cities or regions.
A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation is referred to as banded structure. Rainbands within tropical cyclones are curved in orientation. Tropical cyclone rainbands contain showers and thunderstorms that, together with the eyewall and the eye, constitute a hurricane or tropical storm. The extent of rainbands around a tropical cyclone can help determine the cyclone's intensity.
A mesoscale convective system (MCS) is a complex of thunderstorms that becomes organized on a scale larger than the individual thunderstorms but smaller than extratropical cyclones, and normally persists for several hours or more. A mesoscale convective system's overall cloud and precipitation pattern may be round or linear in shape, and include weather systems such as tropical cyclones, squall lines, lake-effect snow events, polar lows, and Mesoscale Convective Complexes (MCCs), and generally form near weather fronts. The type that forms during the warm season over land has been noted across North America, Europe, and Asia, with a maximum in activity noted during the late afternoon and evening hours.
This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.
The climate of the north and central parts of the US state of Florida is humid subtropical. Most of South Florida has a tropical climate. There is a defined rainy season from May through October, when air mass thundershowers that build in the heat of the day drop heavy but brief summer rainfall. Late summer and early fall bring decaying tropical lows that contribute to late summer and early fall rains.
Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes.
The following outline is provided as an overview of and topical guide to meteorology:
The Tampa Bay area has a humid subtropical climate. There are two basic seasons in the Tampa Bay area, a hot and wet season from May through October, and a mild and dry season from November through April.
The following outline is provided as an overview of and topical guide to tropical cyclones:
The December 2009 Midwest blizzard was a powerful extratropical cyclone which was of a category which meteorologists refer to as a cyclogenic bomb, a system which shows a drop in central pressure similar to the Rapid Intensification Cycle of a tropical cyclone, more than 1 mbar per hour for 12 to 24 hours or more. A sustained drop averaging more than 2.5 mbar/hr is termed explosive deepening/intensification, and this was the case with this rapidly deepening and intensifying storm as it traversed the Midwest and Ontario and on to Québec, Greenland and vicinity. In many locations wind, snowfall, and precipitation moisture content records dating back to the December 2, 1990 storm, the 1976-1978 period, the 1949 blizzard, or even further back were broken, with barometric pressure records falling as well. Both the central pressure (depth) and rate of change and differential over a given distance (intensity) were remarkable, and both caused hurricane-force winds in places.
This glossary of meteorology is a list of terms and concepts relevant to meteorology and the atmospheric sciences, their sub-disciplines, and related fields.
Ohio school districts can use five calamity days before they must start adding extra days to the school calendar.