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101-402: A derecho ( / ˈ d ɛ r ə tʃ oʊ / , from Spanish: derecho [deˈɾetʃo] , 'straight') is a widespread, long-lived, straight-line wind storm that is associated with a fast-moving group of severe thunderstorms known as a mesoscale convective system . Derechos cause hurricane-force winds, heavy rains, and flash floods . In many cases, convection -induced winds take on

202-701: A bow echo (backward "C") form of squall line , often forming beneath an area of diverging upper tropospheric winds, and in a region of both rich low-level moisture and warm-air advection . Derechos move rapidly in the direction of movement of their associated storms, similar to an outflow boundary (gust front), except that the wind remains sustained for a greater period of time (often increasing in strength after onset), and may reach tornado- and hurricane-force winds. A derecho-producing convective system may remain active for many hours and, occasionally, over multiple days. A warm-weather phenomenon, derechos mostly occur in summer, especially during June, July, and August in

303-413: A capping inversion is released when the "lid" is broken by heating or mechanical lift. The amount of CAPE also modulates how low-level vorticity is entrained and then stretched in the updraft , with importance to tornadogenesis . The most important CAPE for tornadoes is within the lowest 1 to 3 km (0.6 to 1.9 mi) of the atmosphere, whilst deep layer CAPE and the width of CAPE at mid-levels

404-433: A hydrolapse (an area of rapidly decreasing dew point temperatures with height) results in the region where the moist boundary layer and mid-level air meet. As daytime heating increases mixing within the moist boundary layer, some of the moist air will begin to interact with the dry mid-level air above it. Owing to thermodynamic processes, as the dry mid-level air is slowly saturated its temperature begins to drop, increasing

505-569: 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

606-484: A thermodynamic or sounding diagram (e.g., a Skew-T log-P diagram ) using air temperature and dew point data usually measured by a weather balloon . CAPE is effectively positive buoyancy, expressed B+ or simply B ; the opposite of convective inhibition (CIN) , which is expressed as B- , and can be thought of as "negative CAPE". As with CIN, CAPE is usually expressed in J/kg but may also be expressed as m /s , as

707-457: 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 . There are many varieties and names for storms: A strict meteorological definition of

808-602: A concentrated area of convectively-induced wind gusts exceeding 25 m/s (50 kn). According to the National Weather Service (NWS) criterion, a derecho is classified as a band of storms that have winds of at least 25 m/s (50 kn) along the entire span of the storm front, maintained over a time span of at least six hours. Some studies add a requirement that no more than two or three hours separate any two successive wind reports. A more recent, more physically based definition of "derecho" proposes that

909-641: A few areas relatively frequently. Outside North America, they sometimes are called by different names. For example, in Bangladesh and parts of Eastern India , a type of storm known as "Kalbaisakhi" or " Nor'westers " may be a progressive derecho. One such event occurred on 10 July 2002 in Germany: a serial derecho killed eight people and injured 39 near Berlin. Derechos occur in southeastern South America (particularly Argentina and southern Brazil) and South Africa as well, and on rarer occasions, close to or north of

1010-579: 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

1111-403: A greater density related to water loading. RCAPE is calculated using the same formula as CAPE, the difference in the formula being in the virtual temperature . In this new formulation, we replace the parcel saturation mixing ratio (which leads to the condensation and vanishing of liquid water) with the parcel water content. This slight change can drastically change the values we get through

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1212-414: 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

1313-428: 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

1414-424: A layer of CIN ( subsidence ) is present, it is unavailable to deep, moist convection until CIN is exhausted. When there is mechanical lift to saturation , cloud base begins at the lifted condensation level (LCL); absent forcing, cloud base begins at the convective condensation level (CCL) where heating from below causes spontaneous buoyant lifting to the point of condensation when the convective temperature

1515-403: A layer of non-positive buoyancy. The atmosphere is warm at the surface and lower levels of the troposphere where there is mixing (the planetary boundary layer (PBL) ), but becomes substantially cooler with height. The temperature profile of the atmosphere, the change in temperature, the degree that it cools with height, is the lapse rate . When the rising air parcel cools more slowly than

1616-542: A more precise, physically based definition of "derecho" has been introduced within the meteorological community. Derecho comes from the Spanish adjective for "straight" (or "direct"), in contrast with a tornado which is a "twisted" wind . The word was first used in the American Meteorological Journal in 1888 by Gustavus Detlef Hinrichs in a paper describing the phenomenon and based on

1717-411: 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

1818-456: 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

1919-441: A result, companies with outside facilities have begun installing such facilities underground, 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

2020-487: 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 . Convective available potential energy More technically, CAPE is the integrated amount of work that the upward (positive) buoyancy force would perform on a given mass of air (called an air parcel ) if it rose vertically through

2121-431: A significant derecho event that crossed Iowa on 31 July 1877. Organized areas of thunderstorm activity reinforce pre-existing frontal zones, and can outrun cold fronts . The resultant mesoscale convective system (MCS) often forms at the point of the strongest divergence of the upper-level flow, and new storm cells are developed in the area with the greatest low-level inflow. The convection tends to move east or toward

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2222-484: 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

2323-460: A sounding diagram, CAPE is the positive area above the LFC, the area between the parcel's virtual temperature line and the environmental virtual temperature line where the ascending parcel is warmer than the environment. Neglecting the virtual temperature correction may result in substantial relative errors in the calculated value of CAPE for small CAPE values. CAPE may also exist below the LFC, but if

2424-711: A stable layer (though momentum, gravity, and other forcing may cause the parcel to continue). There are multiple types of CAPE, downdraft CAPE ( DCAPE ), estimates the potential strength of rain and evaporatively cooled downdrafts . Other types of CAPE may depend on the depth being considered. Other examples are surface based CAPE ( SBCAPE ), mixed layer or mean layer CAPE ( MLCAPE ), most unstable or maximum usable CAPE ( MUCAPE ), and normalized CAPE ( NCAPE ). Fluid elements displaced upwards or downwards in such an atmosphere expand or compress adiabatically in order to remain in pressure equilibrium with their surroundings, and in this manner become less or more dense. If

2525-458: 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

2626-529: A terrestrial thunderhead. The east–west extent of the same-year storm equaled 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

2727-684: A third of the state of Iowa's agricultural area. Over a million homes across the Midwest were without basic services such as water and electricity. Iowa Governor Reynolds requested $ 4 billion in federal aid to assist in the recovery efforts. Winds were confirmed as having stirred up in Colorado and Nebraska, and then proceeded in force crossing 5 states including Iowa, Minnesota, Illinois, Indiana, and Ohio leaving destruction in excess of $ 7.5 billion in estimated damages. The 21 May 2022 derecho in southern Ontario and western Quebec travelled lengthwise along

2828-665: A warm core, like other mesoscale convective systems. One such derecho occurred across the Midwestern U.S. on 21 July 2003. An area of convection developed across eastern Iowa near a weak stationary/warm front and ultimately matured, taking on the shape of a wavy squall line across western Ohio and southern Indiana . The system re-intensified after leaving the Ohio Valley, starting to form a large hook, with occasional hook echoes appearing along its eastern side. A surface low pressure center formed and became more impressive later in

2929-538: 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 Giovanni Domenico Cassini . Neptune also had its own lesser-known Great Dark Spot . In September 1994, the Hubble Space Telescope – using Wide Field Planetary Camera 2 – imaged storms on Saturn generated by upwelling of warmer air, similar to

3030-404: Is a good example. Importantly in that case, was that although overall CAPE was weak, there was strong CAPE in the lowest levels of the troposphere which enabled an outbreak of minisupercells producing large, long-track, intense tornadoes. A good example of convective instability can be found in our own atmosphere. If dry mid-level air is drawn over very warm, moist air in the lower troposphere ,

3131-439: Is also termed static instability , because the instability does not depend on the existing motion of the air; this contrasts with dynamic instability where instability is dependent on the motion of air and its associated effects such as dynamic lifting . Thunderstorms form when air parcels are lifted vertically. Deep, moist convection requires a parcel to be lifted to the LFC where it then rises spontaneously until reaching

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3232-650: 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

3333-447: Is important for supercells . Tornado outbreaks tend to occur within high CAPE environments. Large CAPE is required for the production of very large hail, owing to updraft strength, although a rotating updraft may be stronger with less CAPE. Large CAPE also promotes lightning activity. Two notable days for severe weather exhibited CAPE values over 5 kJ/kg. Two hours before the 1999 Oklahoma tornado outbreak occurred on May 3, 1999,

3434-423: Is lost instantaneously during condensation . This process is thus irreversible upon adiabatic descent. This process is not realistic for tropical cyclones. To make the process more realistic for tropical cyclones is to use Reversible CAPE (RCAPE for short). RCAPE assumes the opposite extreme to the standard convention of CAPE and is that no liquid water will be lost during the process. This new process gives parcels

3535-416: Is one of the most significant thunderstorm hazards to aircraft. When hail stones exceed 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

3636-476: 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

3737-516: Is reached. When CIN is absent or is overcome, saturated parcels at the LCL or CCL, which had been small cumulus clouds , will rise to the LFC, and then spontaneously rise until hitting the stable layer of the equilibrium level. The result is deep, moist convection (DMC), or simply, a thunderstorm. When a parcel is unstable, it will continue to move vertically, in either direction, dependent on whether it receives upward or downward forcing, until it reaches

3838-423: 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

3939-557: 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. 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

4040-465: Is the height of the level of free convection and z n {\displaystyle z_{\mathrm {n} }} is the height of the equilibrium level (neutral buoyancy), where T v , p a r c e l {\displaystyle T_{\mathrm {v,parcel} }} is the virtual temperature of the specific parcel, where T v , e n v {\displaystyle T_{\mathrm {v,env} }}

4141-453: Is the virtual temperature of the environment (note that temperatures must be in the Kelvin scale), and where g {\displaystyle g} is the acceleration due to gravity . This integral is the work done by the buoyant force minus the work done against gravity, hence it's the excess energy that can become kinetic energy. CAPE for a given region is most often calculated from

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4242-788: The 60th parallel in northern Canada. Primarily a mid-latitudes phenomenon, derechos do occur in the Amazon Basin of Brazil. On 8 August 2010, a derecho struck Estonia and tore off the tower of Väike-Maarja Church. Derechos are occasionally observed in China. Since derechos occur during warm months and often in places with cold winter climates, people who are most at risk are those involved in outdoor activities. Campers, hikers, and motorists are most at risk because of falling trees toppled over by straight-line winds. Wide swaths of forest have been felled by such storms. People who live in mobile homes are also at risk; mobile homes that are not anchored to

4343-592: The Deep South , although a late-summer derecho struck upper parts of the New York State area after midnight on 7 September 1998. Warm season derechos have greater instability than their cold season counterpart, while cool season derechos have greater shear than their warm season counterpart. Although these storms most commonly occur in North America, derechos can occur elsewhere in the world, with

4444-516: The Storm Prediction Center of the U.S. National Oceanic & Atmospheric Administration . Some derechos develop a radar signature resembling that of a hurricane in the low levels. They may have a central eye free of precipitation, with a minimum central pressure and surrounding bands of strong convection, but are really associated with an MCS developing multiple squall lines, and are not tropical in nature. These storms have

4545-425: The adiabatic lapse rate . Under certain conditions, the lapse rate can increase significantly in a short amount of time, resulting in convection . High convective instability can lead to severe thunderstorms and tornadoes as moist air which is trapped in the boundary layer eventually becomes highly negatively buoyant relative to the adiabatic lapse rate and escapes as a rapidly rising bubble of humid air triggering

4646-635: The atmosphere such as in a dust storm , among other forms of severe weather . 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 and horizontal 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. The English word comes from Proto-Germanic *sturmaz meaning "noise, tumult". Storms are created when

4747-605: The equator , roughly parallel to low-level thickness lines and usually somewhat to the right of the mean tropospheric flow. When the convection is strongly linear or slightly curved, the MCS is called a squall line, with the strongest winds typically occurring just behind the leading edge of the significant wind shift and pressure rise. Classic derechos occur with squall lines that contain bow- or spearhead-shaped features as seen by weather radar that are known as bow echoes or spearhead echoes . Squall lines typically "bow out" due to

4848-594: The equilibrium level (EL): C A P E = ∫ z f z n g ( T v , p a r c e l − T v , e n v T v , e n v ) d z {\displaystyle \mathrm {CAPE} =\int _{z_{\mathrm {f} }}^{z_{\mathrm {n} }}g\left({\frac {T_{\mathrm {v,parcel} }-T_{\mathrm {v,env} }}{T_{\mathrm {v,env} }}}\right)\,dz} Where z f {\displaystyle z_{\mathrm {f} }}

4949-560: 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 people and caused $ 9.14 billion (2005 USD) in damage. Hail

5050-415: The troposphere , the free convective layer (FCL), where an ascending air parcel is warmer than the ambient air. CAPE is measured in joules per kilogram of air (J/kg). Any value greater than 0 J/kg indicates instability and an increasing possibility of thunderstorms and hail. Generic CAPE is calculated by integrating vertically the local buoyancy of a parcel from the level of free convection (LFC) to

5151-730: 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 Bermuda and provided the inspiration for Shakespeare's play The Tempest (1611). Specifically, Sir Thomas Gates , future governor of Virginia ,

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5252-684: 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

5353-473: 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

5454-459: The CAPE value sounding at Oklahoma City was at 5.89 kJ/kg. A few hours later, an F5 tornado ripped through the southern suburbs of the city. Also on May 4, 2007, CAPE values of 5.5 kJ/kg were reached and an EF5 tornado tore through Greensburg, Kansas . On these days, it was apparent that conditions were ripe for tornadoes and CAPE wasn't a crucial factor. However, extreme CAPE, by modulating

5555-463: 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),

5656-768: The Midwestern United States, across the central Appalachians, into the Mid-Atlantic States during a heat wave . The August 2020 Midwest Derecho delivered a maximum measured wind speed of 56 m/s (109 kn), with damage-estimated speeds as high as 63 m/s (120 kn) in the Cedar Rapids, Iowa area. The storm was referred to as one of the largest "land-based hurricanes" in recorded history spawning 17 confirmed tornadoes across Wisconsin, Illinois, and Indiana. Ten million acres of crops were damaged or destroyed, accounting for roughly

5757-493: The Northern Hemisphere, derechos generally develop within a pattern of mid-tropospheric southwesterly winds, in an environment of low to moderate atmospheric instability (caused by relative warmth and moisture near ground level, with cooler air aloft, as measured by convective available potential energy ), and high values of vertical wind shear (20 m/s or 40 knots within the lowest 5 km or 16,000 ft of

5858-542: The Northern Hemisphere, or March, April, and May in the Southern Hemisphere, within areas of moderately strong instability and moderately strong vertical wind shear . However, derechos can occur at any time of the year. They are equally likely during day and night times. Various studies since the 1980s have shed light on the physical processes responsible for the production of widespread damaging winds by thunderstorms. In addition, it has become apparent that

5959-424: 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 ) Many winter sports , such as skiing , snowboarding , snowmobiling , and snowshoeing depend upon snow. Where snow

6060-666: The United States National Weather Service and other organizations show that a large swath of the north-central United States, and presumably at least the adjacent sections of Canada and much of the surface of the Great Lakes, can expect winds from 40 to 55 m/s (75 to 105 kn) over a significant area at least once in any 50-year period, including both convective events and extra-tropical cyclones and other events deriving power from baroclinic sources. Only in 40 to 65 percent or so of

6161-469: The United States resting on the coast of the Atlantic basin, and a fraction of the Everglades, are derechos surpassed in this respect — by landfalling hurricanes , which at their worst may have winds as severe as EF3 tornadoes. Certain derecho situations are the most common instances of severe weather outbreaks which may become less favorable to tornado production as they become more violent;

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6262-480: The additional damage caused by straight-line winds in the immediate area. With the average tornado in the United States and Canada rating in the low end of the F/ EF 1 classification at 40 to 45 m/s (75 to 85 kn) peak winds and most or all of the rest of the world even lower, derechos tend to deliver the vast majority of extreme wind conditions over much of the territory in which they occur. Datasets compiled by

6363-414: The adiabatic decrease or increase in density is less than the decrease or increase in the density of the ambient (not moved) medium, then the displaced fluid element will be subject to downwards or upwards pressure, which will function to restore it to its original position. Hence, there will be a counteracting force to the initial displacement. Such a condition is referred to as convective stability . On

6464-566: 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 17 May 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

6565-624: 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

6666-468: The atmosphere). Warm season derechos in the Northern Hemisphere most often form in west to northwesterly flow at mid-levels of the troposphere , with moderate to high levels of thermodynamic instability. As previously mentioned, derechos favor environments of low-level warm advection and significant low-level moisture. A common definition is a thunderstorm complex that produces a damaging wind swath of at least 390–640 kilometres (240–400 mi), featuring

6767-544: 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 (8 February 1894 – 1 November 1982) survived the Galveston Hurricane of 1900 as a boy. Based on that experience, he published

6868-582: 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 23 July 2010, in Vivian, 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). This broke

6969-445: 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. Storms do not only occur on Earth; other planetary bodies with a sufficient atmosphere ( giant planets in particular) also undergo stormy weather. The Great Red Spot on Jupiter provides

7070-580: 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 Booker Prize -winning novel by A. S. Byatt . The Great Storm of 1987 occurred on

7171-523: The criteria for a storm to be classified as a derecho. A wind storm must meet the following criteria: Prior to January 11, 2022, the definition for a derecho was: Four types of derechos are generally recognized: Winds in a derecho can be enhanced by downburst clusters embedded inside the storm. These straight-line winds may exceed 45 m/s (85 kn), reaching 60 m/s (115 kn) in past events. Tornadoes sometimes form within derecho events, although such events are often difficult to confirm due to

7272-598: The day. Another example is the May 2009 Southern Midwest derecho . Derechos in North America form predominantly from April to August, peaking in frequency from May into July. During this time of year, derechos are mostly found in the Midwestern United States and the U.S. Interior Highlands most commonly from Oklahoma and across the Ohio Valley . During mid-summer when a hot and muggy air mass covers

7373-557: The development of a cumulus or cumulonimbus cloud. As with most parameters used in meteorology , there are some caveats to keep in mind, one of which is what CAPE represents physically and in what instances CAPE can be used. One example where the more common method for determining CAPE might start to break down is in the presence of tropical cyclones (TCs), such as tropical depressions, tropical storms, or hurricanes . The more common method of determining CAPE can break down near tropical cyclones because CAPE assumes that liquid water

7474-403: The entire atmosphere. Positive CAPE will cause the air parcel to rise, while negative CAPE will cause the air parcel to sink. Nonzero CAPE is an indicator of atmospheric instability in any given atmospheric sounding , a necessary condition for the development of cumulus and cumulonimbus clouds with attendant severe weather hazards. CAPE exists within the conditionally unstable layer of

7575-483: 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)

7676-401: The formation of a mesoscale high-pressure system which forms within the stratiform rain area behind the initial convective line. This high-pressure area is formed due to strong descending air currents behind the squall line, and could come in the form of a downburst . The size of the bow may vary, and the storms associated with the bow may die and redevelop. During the cool season within

7777-624: The ground may be overturned from the high winds. Across the United States, Michigan and New York have incurred many of the fatalities from derechos. Prior to Hurricane Katrina , the death tolls from derechos and hurricanes were comparable for the United States. Derechos may also severely damage an urban area's electrical distribution system, especially if these services are routed above ground. The derecho that struck Chicago, Illinois on 11 July 2011 left more than 860,000 people without electricity. The June 2012 North American derecho took out electrical power to more than 3.7 million customers starting in

7878-516: The height of 30–31 May 1998 upper Middle West-Canada-New York State derecho and the latter stages of significant tornado and severe weather outbreaks in 2003 and 2004 are only three examples of this. Some upper-air measurements used for severe-weather forecasting may reflect this point of diminishing return for tornado formation, and the mentioned three situations were instances during which the rare Particularly Dangerous Situation severe thunderstorm variety of severe weather watches were issued from

7979-502: 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. 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

8080-494: The most damaging derechos are associated with particular types of mesoscale convective systems that are self-perpetuating (meaning that the convective systems are not strongly dependent on the larger-scale meteorological processes such as those associated with blizzard -producing winter storms and strong cold fronts). In addition, the term "derecho" sometimes is misapplied to convectively generated wind events that are not particularly well-organized or long-lasting. For these reasons,

8181-558: The most heavily populated region in Canada, reaching peak wind speeds of 190 km/h. The derecho killed 10 people and caused $ 875 million property damage, the sixth largest "insured loss event" in Canadian history. Destruction of utility poles deprived some rural communities of telephone and electricity services for several weeks. Derechos can be hazardous to aviation due to embedded microbursts, downbursts, and downburst clusters. In addition,

8282-584: The night of 15–16 October 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 (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). Hurricane Katrina (2005) has been featured in

8383-511: The north-central U.S., they will often develop farther north into Manitoba or Northwestern Ontario , sometimes well north of the Canada–US border. North Dakota , Minnesota , and upper Michigan are also vulnerable to derecho storms when such conditions are in place. They often occur along stationary fronts on the northern periphery of where the most intense heat and humidity bubble exists. Late-year derechos are normally confined to Texas and

8484-401: The other hand, if adiabatic decrease or increase in density is greater than in the ambient fluid, the upwards or downwards displacement will be met with an additional force in the same direction exerted by the ambient fluid. In these circumstances, small deviations from the initial state will become amplified. This condition is referred to as convective instability . Convective instability

8585-606: The powerful updrafts and high cloud tops can cause for dangerous conditions. Their sheer size also makes them very difficult to navigate around. Wind storm A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. 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), wind transporting some substance through

8686-585: The previous record for diameter set by a hailstone 7 inches (18 cm) diameter and 18.75 inches (47.6 cm) circumference which fell in Aurora, 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 in Coffeyville, Kansas in 1970. Various hazards, ranging from hail to lightning can affect outside technology facilities, such as antennas , satellite dishes , and towers. As

8787-570: 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 uses 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

8888-492: 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 . 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

8989-503: 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,

9090-446: The surrounding atmosphere, it remains warmer and less dense . The parcel continues to rise freely ( convectively ; without mechanical lift) through the atmosphere until it reaches an area of air less dense (warmer) than itself. The amount, and shape, of the positive-buoyancy area modulates the speed of updrafts , thus extreme CAPE can result in explosive thunderstorm development; such rapid development usually occurs when CAPE stored by

9191-466: The term be reserved for use with convective systems that not only contain unique radar-observed features such as bow echoes and mesovortices , but also for events that produce damage swaths at least 100 km (60 miles) wide and 650 km (400 miles) long. On January 11, 2022, the National Oceanic and Atmospheric Administration and Environment and Climate Change Canada formally revised

9292-726: The updraft (and downdraft), can allow for exceptional events, such as the deadly F5 tornadoes that hit Plainfield, Illinois on August 28, 1990, and Jarrell, Texas on May 27, 1997, on days which weren't readily apparent as conducive to large tornadoes. CAPE was estimated to exceed 8 kJ/kg in the environment of the Plainfield storm and was around 7 kJ/kg for the Jarrell storm . Severe weather and tornadoes can develop in an area of low CAPE values. The surprise severe weather event that occurred in Illinois and Indiana on April 20, 2004,

9393-402: The values are equivalent. In fact, CAPE is sometimes referred to as positive buoyant energy ( PBE ). This type of CAPE is the maximum energy available to an ascending parcel and to moist convection. When a layer of CIN is present, the layer must be eroded by surface heating or mechanical lifting, so that convective boundary layer parcels may reach their level of free convection (LFC). On

9494-441: 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

9595-419: 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

9696-483: 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

9797-542: 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

9898-417: 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

9999-525: 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

10100-500: 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

10201-423: 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 and HD 80606 b . The former's storm was discovered on 23 June 2010, and measured at 6,200 km/h (3,900 mph), while

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