Thunderstorm

“Electrical storm” redirects here. For other uses, seeElectrical storm (disambiguation).“TSTM” redirects here. For the musical ensemble, seeThirty Seconds to Mars.For the Chinese play, see Thunderstorm (play).A thunderstorm, also known as an electrical storm, a

A typical thunderstorm over a field

lightning storm, or a thundershower, is a type of stormcharacterized by the presence of lightning and its acousticeffect on the Earth’s atmosphere known as thunder.[1]Thunderstorms occur in association with a type of cloudknown as a cumulonimbus. They are usually accompa-nied by strong winds, heavy rain and sometimes snow,sleet, hail, or, in contrast, no precipitation at all. Thun-derstorms may line up in a series or rainband, known asa squall line. Strong or severe thunderstorms may ro-tate, known as supercells. While most thunderstormsmove with the mean wind flow through the layer of thetroposphere that they occupy, vertical wind shear causesa deviation in their course at a right angle to the windshear direction.Thunderstorms result from the rapid upward movementof warm, moist air. They can occur inside warm, moistair masses and at fronts. As the warm, moist air movesupward, it cools, condenses, and forms cumulonimbusclouds that can reach heights of over 20 km (12.45miles).As the rising air reaches its dew point, water droplets andice form and begin falling the long distance through theclouds towards the Earth’s surface. As the droplets fall,they collide with other droplets and become larger. Thefalling droplets create a downdraft of cold air and mois-ture that spreads out at the Earth’s surface, causing thestrong winds commonly associated with thunderstorms,and occasionally fog.Thunderstorms can generally form and develop in any

Warm, moist updraft from a thunderstorm associated with asouthward-moving frontal boundary. Taken from Texarkana,Texas looking north.

particular geographic location, perhaps most frequentlywithin areas located at mid-latitude when warm moistair collides with cooler air.[2] Thunderstorms are respon-sible for the development and formation of many se-vere weather phenomena. Thunderstorms, and the phe-nomena that occur along with them, pose great haz-ards to populations and landscapes. Damage that re-sults from thunderstorms is mainly inflicted by downburstwinds, large hailstones, and flash flooding caused byheavy precipitation. Stronger thunderstorm cells are ca-pable of producing tornadoes and waterspouts.There are four types of thunderstorms: single-cell, mul-ticell cluster, multicell lines, and supercells. Supercellthunderstorms are the strongest and the most associatedwith severe weather phenomena. Mesoscale convectivesystems formed by favorable vertical wind shear withinthe tropics and subtropics are responsible for the devel-opment of hurricanes. Dry thunderstorms, with no pre-

1

2 1 LIFE CYCLE

cipitation, can cause the outbreak of wildfires with theheat generated from the cloud-to-ground lightning thataccompanies them. Several methods are used to studythunderstorms, such as weather radar, weather stations,and video photography. Past civilizations held variousmyths concerning thunderstorms and their developmentas late as the 18th century. Other than within the Earth’satmosphere, thunderstorms have also been observed onJupiter and Venus.

1 Life cycle

Stages of a thunderstorm’s life.

See also: Cloud

Warm air has a lower density than cool air, so warmer airrises upwards and cooler air will settle at the bottom[3]

(this effect can be seen with a hot air balloon).[4] Cloudsform as relatively warmer air carrying moisture riseswithin cooler air. As the moist air rises, it cools caus-ing some of the water vapor in the rising packet of air tocondense.[5] When the moisture condenses, it releases en-ergy known as latent heat of vaporization, which allowsthe rising packet of air to cool less than the surround-ing air,[6] continuing the cloud’s ascension. If enoughinstability is present in the atmosphere, this processwill continue long enough for cumulonimbus clouds toform, which support lightning and thunder. Meteorolog-ical indices such as convective available potential energy(CAPE) and the lifted index can be used to assist in deter-mining upward vertical development of clouds.[7] Gener-ally, thunderstorms require three conditions to form:

1. Moisture

2. An unstable airmass

3. A lifting force (heat)

All thunderstorms, regardless of type, go through threestages: the developing stage, the mature stage, andthe dissipation stage.[8] The average thunderstorm hasa 24 km (15 mi) diameter. Depending on the conditionspresent in the atmosphere, these three stages take an av-erage of 30 minutes to go through.[9]

1.1 Cumulus stage

The first stage of a thunderstorm is the cumulus stage,or developing stage. In this stage, masses of moistureare lifted upwards into the atmosphere. The trigger forthis lift can be insolation heating the ground producingthermals, areas where two winds converge forcing air up-wards, or where winds blow over terrain of increasingelevation. The moisture rapidly cools into liquid dropsof water due to the cooler temperatures at high altitude,which appears as cumulus clouds. As the water vapor con-denses into liquid, latent heat is released, which warmsthe air, causing it to become less dense than the surround-ing dry air. The air tends to rise in an updraft throughthe process of convection (hence the term convective pre-cipitation). This creates a low-pressure zone beneath theforming thunderstorm. In a typical thunderstorm, ap-proximately 5×108 kg of water vapor are lifted into theEarth’s atmosphere.[10]

1.2 Mature stage

Anvil-shaped thundercloud in the mature stage over Swifts Creek,Victoria

In the mature stage of a thunderstorm, the warmed aircontinues to rise until it reaches an area of warmer airand can rise no farther. Often this 'cap' is the tropopause.The air is instead forced to spread out, giving the storm acharacteristic anvil shape. The resulting cloud is calledcumulonimbus incus. The water droplets coalesce intolarger and heavier droplets and freeze to become ice parti-cles. As these fall theymelt to become rain. If the updraftis strong enough, the droplets are held aloft long enoughto become so large they do not melt completely, and fallas hail. While updrafts are still present, the falling raincreates downdrafts as well. The simultaneous presence ofboth an updraft and downdrafts marks the mature stageof the storm, and produces cumulonimbus clouds. Dur-ing this stage, considerable internal turbulence can occurin the storm system, which manifests as strong winds, se-vere lightning, and even tornadoes.[11]

Typically, if there is little wind shear, the storm willrapidly enter the dissipating stage and 'rain itself out',[8]but if there is sufficient change in wind speed and/or di-rection the downdraft will be separated from the updraft,and the storm may become a supercell, and the maturestage can sustain itself for several hours.[12]

2.1 Single-cell 3

1.3 Dissipating stage

A thunderstorm in an environment with no winds to shear thestorm or blow the anvil in any one direction

In the dissipation stage, the thunderstorm is dominatedby the downdraft. If atmospheric conditions do not sup-port super cellular development, this stage occurs ratherquickly, approximately 20–30 minutes into the life of thethunderstorm. The downdraft will push down out of thethunderstorm, hit the ground and spread out. This phe-nomenon is known as a downburst. The cool air carriedto the ground by the downdraft cuts off the inflow of thethunderstorm, the updraft disappears and the thunder-storm will dissipate. Thunderstorms in an atmospherewith virtually no vertical wind shear weaken as soon asthey send out an outflow boundary in all directions, whichthen quickly cuts off its inflow of relatively warm, moistair and kills the thunderstorm.[13] The downdraft hittingthe ground creates an outflow boundary. This can causedownbursts, a potential hazardous condition for aircraftthat fly through it, as a substantial change in wind speedand direction occurs, resulting in decrease of airspeed andsubsequent reduction in lift of the aircraft. The strongerthe outflow boundary is, the stronger the resultant verticalwind shear becomes.[14]

2 Classification

Conditions favorable for thunderstorm types and complexes

There are four main types of thunderstorms: single-cell,multi-cell, squall line (also called multi-cell line) and su-percell. Which type forms depends on the instability and

relative wind conditions at different layers of the atmo-sphere ("wind shear"). Single-cell thunderstorms formin environments of low vertical wind shear and last only20–30 minutes. Organized thunderstorms and thunder-storm clusters/lines can have longer life cycles as theyform in environments of significant vertical wind shear,which aids the development of stronger updrafts as wellas various forms of severe weather. The supercell is thestrongest of the thunderstorms, most commonly associ-ated with large hail, high winds, and tornado formation.

2.1 Single-cell

Main article: Air-mass thunderstormThis term technically applies to a single thunderstorm

A single-cell thunderstorm over Wagga Wagga.

with one main updraft. Also known as air-mass thun-derstorms, these are the typical summer thunderstormsin many temperate locales. They also occur in the coolunstable air that often follows the passage of a cold frontfrom the sea during winter. Within a cluster of thunder-storms, the term “cell” refers to each separate principalupdraft. Thunderstorm cells occasionally form in isola-tion, as the occurrence of one thunderstorm can developan outflow boundary that sets up new thunderstorm de-velopment. Such storms are rarely severe and are a re-sult of local atmospheric instability; hence the term “airmass thunderstorm”. When such storms have a brief pe-riod of severe weather associated with them, it is knownas a pulse severe storm. Pulse severe storms are poorly

4 2 CLASSIFICATION

organized and occur randomly in time and space, mak-ing them difficult to forecast. Single-cell thunderstormsnormally last 20–30 minutes.[9]

2.2 Multi-cell clusters

Main article: Multicellular thunderstormThis is the most common type of thunderstorm devel-

A group of thunderstorms over Brazil photographed by the SpaceShuttle Challenger.

opment. Mature thunderstorms are found near the centerof the cluster, while dissipating thunderstorms exist ontheir downwind side. Multicell storms form as clusters ofstorms but may then evolve into one or more squall lines.While each cell of the cluster may only last 20 minutes,the cluster itself may persist for hours at a time. Theyoften arise from convective updrafts in or near mountainranges and linear weather boundaries, such as strong coldfronts or troughs of low pressure. These type of stormsare stronger than the single-cell storm, yet much weakerthan the supercell storm. Hazards with the multicell clus-ter include moderate-sized hail, flash flooding, and weaktornadoes.[9]

2.3 Multicell lines

Main article: Squall lineSee also: List of derecho events

A squall line is an elongated line of severe thunderstormsthat can form along and/or ahead of a cold front.[15][16]In the early 20th century, the term was used as a syn-onym for cold front.[17] The squall line contains heavyprecipitation, hail, frequent lightning, strong straight linewinds, and possibly tornadoes and waterspouts.[18] Severeweather in the form of strong straight-line winds can be

expected in areas where the squall line itself is in theshape of a bow echo, within the portion of the line thatbows out the most.[19] Tornadoes can be found alongwaves within a line echo wave pattern, or LEWP, wheremesoscale low pressure areas are present.[20] Some bowechoes in the summer are called derechos, andmove quitefast through large sections of territory.[21] On the backedge of the rain shield associated withmature squall lines,a wake low can form, which is a mesoscale low pressurearea that forms behind the mesoscale high pressure sys-tem normally present under the rain canopy, which aresometimes associated with a heat burst.[22] This kind ofstorm is also known as “Wind of the Stony Lake” (Tradi-tional Chinese: – shi2 hu2 feng1, Simplified Chinese:

) in southern China.[23]

2.4 Supercells

Main article: SupercellSupercell storms are large, usually severe, quasi-steady-

A supercell thunderstorm over Chaparral, New Mexico.

The setting sun illuminates the top of a classic anvil-shaped thun-derstorm cloud in eastern Nebraska, United States.

state storms that form in an environment where windspeed or wind direction varies with height (an area of"wind shear"), and they have separate downdrafts and up-drafts (i.e., where its associated precipitation is not fallingthrough the updraft) with a strong, rotating updraft (a

5

"mesocyclone"). These storms normally have such pow-erful updrafts that the top of the supercell storm cloud (oranvil) can break through the troposphere and reach intothe lower levels of the stratosphere, and supercell stormscan be 15 miles (24 km) wide. Research has shown thatat least 90 percent of supercells cause severe weather.[12]These storms can produce destructive tornadoes, some-times F3 or higher, extremely large hailstones (4 inches or10 centimetres diameter), straight-line winds in excess of80mph (130 km/h), and flash floods. In fact, research hasalso shown that most tornadoes occur from this type ofthunderstorm.[24] Supercells are the most powerful typeof thunderstorm.[9]

2.5 Severe thunderstorms

A storm is considered severe if winds reach at least 93kilometres per hour (58 mph), hail is 1 inch (25 mm)in diameter or larger, or if funnel clouds or tornadoes arereported.[25][26][27] Although a funnel cloud or tornado in-dicates a severe thunderstorm, a tornado warning is issuedin place of a severe thunderstorm warning. In Canada, arainfall rate greater than 50millimetres (2 in) in one hour,or 75millimetres (3 in) in three hours, is also used to indi-cate severe thunderstorms.[28] Severe thunderstorms canoccur from any type of storm cell. However, multicell,supercell, and squall lines represent the most commonforms of thunderstorms that produce severe weather.[12]

2.6 Mesoscale convective systems

See also: Mesoscale convective systemA mesoscale convective system (MCS) is a complex

MCC moving through New England: August 2, 2006 0600 UTC

of thunderstorms that becomes organized on a scalelarger than the individual thunderstorms but smaller thanextratropical cyclones, and normally persists for severalhours or more.[29] A mesoscale convective system’s over-all cloud and precipitation pattern may be round or linearin shape, and include weather systems such as tropical cy-clones, squall lines, lake-effect snow events, polar lows,and Mesoscale Convective Complexes (MCCs), and gen-erally form near weather fronts. Most mesoscale convec-tive systems develop overnight and continue their lifes-

pan through the next day.[8] The type that forms duringthe warm season over land has been noted across NorthAmerica, Europe, and Asia, with a maximum in activitynoted during the late afternoon and evening hours.[30][31]

Forms of MCS that develop within the tropics use eitherthe Intertropical Convergence Zone or monsoon troughsas a focus for their development, generally within thewarm season between spring and fall. More intense sys-tems form over land than over water.[32][33] One excep-tion is that of lake-effect snow bands, which form dueto cold air moving across relatively warm bodies of wa-ter, and occurs from fall through spring.[34] Polar lowsare a second special class of MCS. They form at high lat-itudes during the cold season.[35] Once the parent MCSdies, later thunderstorm development can occur in con-nection with its remnant mesoscale convective vortex(MCV).[36] Mesoscale convective systems are importantto the United States rainfall climatology over the GreatPlains since they bring the region about half of their an-nual warm season rainfall.[37]

3 Motion

Thunderstorm line viewed in reflectivity (dBZ) on a plan positionindicator radar display

The two major ways thunderstorms move are via advec-tion of the wind and propagation along outflow bound-aries towards sources of greater heat and moisture. Manythunderstorms move with the mean wind speed throughthe Earth’s troposphere, or the lowest 8 kilometres (5.0mi) of the Earth’s atmosphere. Younger thunderstormsare steered by winds closer to the Earth’s surface thanmore mature thunderstorms, as they are less tall. Orga-nized, long-lived thunderstorm cells and complexes moveat a right angle to the direction of the vertical wind shearvector. If the gust front, or leading edge of the outflowboundary, races ahead of the thunderstorm, its motionwill accelerate in tandem. This is more of a factor withthunderstorms with heavy precipitation (HP) than withthunderstorms with low precipitation (LP). When thun-derstorms merge, which is most likely when numerous

6 4 HAZARDS

thunderstorms exist in proximity to each other, the mo-tion of the stronger thunderstorm normally dictates futuremotion of the merged cell. The stronger the mean wind,the less likely other processes will be involved in stormmotion. On weather radar, storms are tracked by using aprominent feature and tracking it from scan to scan.[12]

3.1 Back-building thunderstorm

A back-building thunderstorm, commonly referred to asa training thunderstorm, is a thunderstorm in which newdevelopment takes place on the upwind side (usually thewest or southwest side in the Northern Hemisphere), suchthat the storm seems to remain stationary or propagate ina backward direction. Though the storm often appearsstationary on radar, or even moving upwind, this is an il-lusion. The storm is really a multi-cell storm with new,more vigorous cells that form on the upwind side, re-placing older cells that continue to drift downwind.[38][39]When this happens, catastrophic flooding is possible. InRapid City, South Dakota, in 1972, an unusual alignmentof winds at various levels of the atmosphere combined toproduce a continuously training set of cells that droppedan enormous quantity of rain upon the same area, result-ing in devastating flash flooding.[40] A similar event oc-curred in Boscastle, England, on 16 August 2004.[41]

4 Hazards

Each year, many people are killed or seriously injured bysevere thunderstorms despite the advance warning. Whilesevere thunderstorms are most common in the spring andsummer, they can occur at just about any time of the year.

4.1 Cloud-to-ground lightning

See also: Lightning and WildfireCloud-to-ground lightning frequently occurs within thephenomena of thunderstorms and have numerous haz-ards towards landscapes and populations. One of themore significant hazards lightning can pose is the wild-fires they are capable of igniting.[42] Under a regime oflow precipitation (LP) thunderstorms, where little pre-cipitation is present, rainfall cannot prevent fires fromstarting when vegetation is dry as lightning produces aconcentrated amount of extreme heat.[43] Direct damagecaused by lightning strikes occurs on occasion.[44] In ar-eas with a high frequency for cloud-to-ground lightning,like Florida, lightning causes several fatalities per year,most commonly to people working outside.[45]

Precipitation with low potential of hydrogen levels (pH),otherwise known as acid rain, is also a frequent risk pro-duced by lightning. Distilled water, which contains nocarbon dioxide, has a neutral pH of 7. Liquids with a pHless than 7 are acidic, and those with a pH greater than 7

A return stroke, cloud-to-ground lightning strike during a thun-derstorm.

are bases. “Clean” or unpolluted rain has a slightly acidicpH of about 5.2, because carbon dioxide and water in theair react together to form carbonic acid, a weak acid (pH5.6 in distilled water), but unpolluted rain also containsother chemicals.[46] Nitric oxide present during thunder-storm phenomena,[47] caused by the splitting of nitrogenmolecules, can result in the production of acid rain, ifnitric oxide forms compounds with the water moleculesin precipitation, thus creating acid rain. Acid rain candamage infrastructures containing calcite or other solidchemical compounds containing carbon. In ecosystems,acid rain can dissolve plant tissues of vegetations and in-crease acidification process in bodies of water and in soil,resulting in deaths of marine and terrestrial organisms.[48]

4.2 Hail

Main article: HailAny thunderstorm that produces hail that reaches the

Hailstorm in Bogotá, Colombia.

ground is known as a hailstorm.[49] Thunderclouds thatare capable of producing hailstones are often seen obtain-ing green coloration. Hail is more common along moun-

4.3 Tornadoes and waterspouts 7

tain ranges because mountains force horizontal winds up-wards (known as orographic lifting), thereby intensify-ing the updrafts within thunderstorms and making hailmore likely.[50] One of the more common regions forlarge hail is across mountainous northern India, whichreported one of the highest hail-related death tolls onrecord in 1888.[51] China also experiences significanthailstorms.[52] Across Europe, Croatia experiences fre-quent occurrences of hail.[53]

In North America, hail is most common in the area whereColorado, Nebraska, andWyoming meet, known as “HailAlley.”[54] Hail in this region occurs between the monthsof March and October during the afternoon and eveninghours, with the bulk of the occurrences fromMay throughSeptember. Cheyenne, Wyoming is North America’smost hail-prone city with an average of nine to ten hail-storms per season.[55] In South America, areas prone tohail are cities like Bogotá, Colombia.Hail can cause serious damage, notably to automobiles,aircraft, skylights, glass-roofed structures, livestock, andmost commonly, farmers’ crops.[55] Hail is one of themost significant thunderstorm hazards to aircraft. Whenhail stones exceed 0.5 inch (13 mm) in diameter, planescan be seriously damaged within seconds.[56] The hail-stones accumulating on the ground can also be hazardousto landing aircraft. Wheat, corn, soybeans, and tobaccoare the most sensitive crops to hail damage.[51] Hail is oneof Canada’s most costly hazards.[57] Hailstorms have beenthe cause of costly and deadly events throughout history.One of the earliest recorded incidents occurred aroundthe 9th century in Roopkund, Uttarakhand, India.[58] Thelargest hailstone in terms of maximum circumference andlength ever recorded in the United States fell in 2003 inAurora, Nebraska, USA.[59]

4.3 Tornadoes and waterspouts

The F5 tornado that struck Elie, Manitoba in 2007.

Main articles: Tornado and Waterspout

A tornado is a violent, rotating column of air in contact

with both the surface of the earth and a cumulonimbuscloud (otherwise known as a thundercloud) or, in rarecases, the base of a cumulus cloud. Tornadoes comein many sizes but are typically in the form of a visiblecondensation funnel, whose narrow end touches the earthand is often encircled by a cloud of debris and dust.[60]Most tornadoes have wind speeds between 40 and 110mph (64 and 177 km/h), are approximately 250 feet (76m) across, and travel a few miles (several kilometers) be-fore dissipating. Some attain wind speeds of more than300 mph (480 km/h), stretch more than one mile (1.6km) across, and stay on the ground for dozens of miles(more than 100 km).[61][62][63]

The Fujita scale and the Enhanced Fujita Scale rate tor-nadoes by damage caused. An EF0 tornado, the weak-est category, damages trees but not substantial structures.An EF5 tornado, the strongest category, rips buildingsoff their foundations and can deform large skyscrapers.The similar TORRO scale ranges from aT0 for extremelyweak tornadoes to T11 for the most powerful knowntornadoes.[64] Doppler radar data, photogrammetry, andground swirl patterns (cycloidal marks) may also be ana-lyzed to determine intensity and award a rating.[65]

Formation of numerous waterspouts in the Great Lakes region.(North America)

A flash flood caused by a severe thunderstorm

Waterspouts have similar characteristics as tornadoes,characterized by a spiraling funnel-shaped wind currentthat form over bodies of water, connecting to large cu-mulonimbus clouds. Waterspouts are generally classi-fied as forms of tornadoes, or more specifically, non-supercelled tornadoes that develop over large bodies of

8 5 SAFETY PRECAUTIONS

water.[66] These spiralling columns of air are frequentlydeveloped within tropical areas close to the equator, butare less common within areas of high latitude.[67]

4.4 Flash flood

Main article: Flash flood

Flash flooding is the process where a landscape, mostnotably an urban environment, is subjected to rapidfloods.[68] These rapid floods occur more quickly andare more localized than seasonal river flooding or arealflooding[69] and are frequently (though not always) as-sociated with intense rainfall.[70] Flash flooding can fre-quently occur in slow-moving thunderstorms and is usu-ally caused by the heavy liquid precipitation that accom-panies it. Flash floods are most common in densely pop-ulated urban environments, where few plants and bodiesof water are present to absorb and contain the extra water.Flash flooding can be hazardous to small infrastructure,such as bridges, and weakly constructed buildings. Plantsand crops in agricultural areas can be destroyed and dev-astated by the force of raging water. Automobiles parkedwithin affected areas can also be displaced. Soil erosioncan occur as well, exposing risks of landslide phenomena.

4.5 Downburst

Main article: DownburstDownburst winds can produce numerous hazards to land-

Trees uprooted or displaced by the force of a downburst wind innorthwest Monroe County, Wisconsin.

scapes experiencing thunderstorms. Downburst windsare generally very powerful, and are often mistakenfor wind speeds produced by tornadoes,[71] due to theconcentrated amount of force exerted by their straight-horizontal characteristic. Downburst winds can be haz-ardous to unstable, incomplete, or weakly constructedinfrastructures and buildings. Agricultural crops, andother plants in nearby environments can be uprooted and

damaged. Aircraft engaged in takeoff or landing cancrash.[8][71] Automobiles can be displaced by the forceexerted by downburst winds. Downburst winds are usu-ally formed in areas when high pressure air systems ofdowndrafts begin to sink and displace the air masses be-low it, due to their higher density. When these down-drafts reach the surface, they spread out and turn into thedestructive straight-horizontal winds.[8]

5 Safety precautions

See also: Emergency management and Tornado pre-paredness

Most thunderstorms come and go fairly uneventfully;however, any thunderstorm can become severe, andall thunderstorms, by definition, present the dangerof lightning.[72] Thunderstorm preparedness and safetyrefers to taking steps before, during, and after a thun-derstorm to minimize injury and damage.

5.1 Preparedness

Preparedness refers to precautions that should be takenbefore a thunderstorm. Some preparedness takes theform of general readiness (as a thunderstorm can occur atany time of the day or year).[73] Preparing a family emer-gency plan, for example, can save valuable time if a stormarises quickly and unexpectedly.[74] Preparing the homeby removing dead or rotting limbs and trees, which canbe blown over in high winds, can also significantly reducethe risk of property damage and personal injury.[75]

The National Weather Service (NWS) in the UnitedStates recommends several precautions that peopleshould take if thunderstorms are likely to occur:[73]

• Know the names of local counties, cities,and towns, as these are how warnings aredescribed.[73]

• Monitor forecasts and weather condi-tions and know whether thunderstormsare likely in the area.[76]

• Be alert for natural signs of an approach-ing storm.

• Cancel or reschedule outdoor events (toavoid being caught outdoors when astorm hits).[76]

• Take action early so you have time to getto a safe place.[76]

• Get inside a substantial building or hard-topped metal vehicle before threateningweather arrives.[76]

• If you hear thunder, get to the safe placeimmediately.[76]

9

• Avoid open areas like hilltops, fields, andbeaches, and don't be or be near the tallestobjects in an area when thunderstormsare occurring.[73][76]

• Don't shelter under tall or isolated treesduring thunderstorms.[76]

• If in the woods, put as much dis-tance between you and any trees duringthunderstorms.[76]

• If in a group, spread out so that youincrease the chances for survivors whocould come to the aid of any victims froma lightning strike.[76]

5.2 Safety

While safety and preparedness often overlap, “thunder-storm safety” generally refers to what people should doduring and after a storm. The American Red Cross rec-ommends that people follow these precautions if a stormis imminent or in progress:[72]

• Take action immediately upon hearingthunder. Anyone close enough to thestorm to hear thunder can be struck bylightning.[75]

• Avoid electrical appliances, includingcorded telephones.[72] Cordless and wire-less telephones are safe to use during athunderstorm.[75]

• Close and stay away from windows anddoors, as glass can become a serious haz-ard in high wind.[72]

• Do not bathe or shower, as plumbing con-ducts electricity.

• If driving, safely exit the roadway, turnon hazard lights, and park. Remain in thevehicle and avoid touching metal.[72]

The NWS stopped recommending the “lightning crouch”in 2008 as it doesn't provide a significant level of pro-tection and will not significantly lower the risk of beingkilled or injured from a nearby lightning strike.[76][77][78]

6 Frequent occurrences

See also: United States rainfall climatologyThunderstorms occur throughout the world, even in thepolar regions, with the greatest frequency in tropicalrainforest areas, where they may occur nearly daily. Atany given time approximately 2,000 thunderstorms areoccurring on Earth.[79] Kampala and Tororo in Ugandahave each been mentioned as the most thunderous places

A mild thunderstorm over Niagara Falls, Ontario.

on Earth,[80] a claim also made for Bogor on Java,Indonesia and Singapore. Other cities known for fre-quent storm activity include Darwin, Caracas, Manila andMumbai. Thunderstorms are associated with the variousmonsoon seasons around the globe, and they populate therainbands of tropical cyclones.[81] In temperate regions,they are most frequent in spring and summer, althoughthey can occur along or ahead of cold fronts at any time ofyear.[82] They may also occur within a cooler air mass fol-lowing the passage of a cold front over a relatively warmerbody of water. Thunderstorms are rare in polar regionsbecause of cold surface temperatures.Some of the most powerful thunderstorms over theUnited States occur in the Midwest and the Southernstates. These storms can produce large hail and power-ful tornadoes. Thunderstorms are relatively uncommonalong much of the West Coast of the United States,[83]but they occur with greater frequency in the inland ar-eas, particularly the Sacramento and San Joaquin Valleysof California. In spring and summer, they occur nearlydaily in certain areas of the Rocky Mountains as part ofthe North American Monsoon regime. In the Northeast,storms take on similar characteristics and patterns as theMidwest, but with less frequency and severity. Duringthe summer, air-mass thunderstorms are an almost dailyoccurrence over central and southern parts of Florida.

7 Types of lightning

Main article: Lightning

Lightning is an electrical discharge that occurs in a thun-derstorm. It can be seen in the form of a bright streak (orbolt) from the sky. Lightning occurs when an electricalcharge is built up within a cloud, due to static electric-ity generated by supercooled water droplets colliding withice crystals near the freezing level. When a large enoughcharge is built up, a large discharge will occur and can beseen as lightning.

10 8 ENERGY

3-second video of a lightning strike within a thunderstorm overIsland in the Sky, Canyonlands National Park, Utah

Cloud to ground lightning over Pentagon City in Arlington,Virginia

Lightning storm over Sydney

The temperature of a lightning bolt can be five times hot-ter than the surface of the sun.[84] Although the light-ning is extremely hot, the duration is short and 90% ofstrike victims survive. Contrary to the popular idea thatlightning does not strike twice in the same spot, some

people have been struck by lightning over three times,and skyscrapers like the Empire State Building have beenstruck numerous times in the same storm.[85]

The loud bang that is heard is the super heated air aroundthe lightning bolt expanding at the speed of sound. Be-cause sound travels much more slowly than light the flashis seen before the bang, although both occur at the samemoment.There are several types of lightning:

• In-cloud lightning is the most common. It is light-ning within a cloud and is sometimes called intra-cloud or sheet lightning.

• Cloud to ground lightning is when a bolt of lightningfrom a cloud strikes the ground. This form poses thegreatest threat to life and property.

• Ground to cloud lightning is when a lightning bolt isinduced from the ground to the cloud.

• Cloud to cloud lightning is rarely seen and is when abolt of lightning arcs from one cloud to another.

• Ball lightning is extremely rare and has several hy-pothesized explanations. It is seen in the form of a15 to 50 centimeter radius ball.[86]

• Cloud to air lightning is when lightning from a cloudhits air of a different charge.[87]

• Dry lightning is a misnomer that refers to a thun-derstorm whose precipitation does not reach theground.

• Heat Lightning refers to a lightning flash that is seenfrom the horizon that does not have accompanyingthunder.[88]

• Upper-atmospheric lightning occurs above the thun-derhead.

• Clear-air lightning is used widely to describe light-ning that occurs with no apparent cloud close enoughto have produced it. In the U.S. and Canadian Rock-ies, a thunderstorm can be in an adjacent valley andnot be observable, (either visually or audibly), fromthe valley where the lightning bolt strikes. Euro-pean and Asian mountainous areas experience sim-ilar events. Also in clear areas where the storm cellis on the near horizon (within 26 km (16 mi) a strikecan occur, and as the storm is so far away, the strikeis referred to as clear-air.

8 Energy

See also: Sprite (lightning), Upper-atmospheric lightningand St. Elmo’s fireIf the quantity of water that is condensed in and sub-

11

How thunderstorms launch particle beams into space

sequently precipitated from a cloud is known, then thetotal energy of a thunderstorm can be calculated. In atypical thunderstorm, approximately 5×108 kg of watervapor are lifted, and the amount of energy released whenthis condenses is 1015 joules. This is on the same or-der of magnitude of energy released within a tropicalcyclone, and more energy than that released during theatomic bomb blast at Hiroshima, Japan in 1945.[10]

The Fermi Gamma-ray Burst Monitor results show thatgamma rays and antimatter particles (positrons) can begenerated in powerful thunderstorms.[89] It is suggestedthat the antimatter positrons are formed in terrestrialgamma-ray flashes (TGF). TGFs are brief bursts occur-ring inside thunderstorms and associated with lightning.The streams of positrons and electrons collide higher inthe atmosphere to generate more gamma rays.[90] About500 TGFs may occur every day worldwide, but mostly goundetected.

9 Studies

In more contemporary times, thunderstorms have takenon the role of a scientific curiosity. Every spring,storm chasers head to the Great Plains of the UnitedStates and the Canadian Prairies to explore the scien-tific aspects of storms and tornadoes through use ofvideotaping.[91] Radio pulses produced by cosmic raysare being used to study how electric charges developwithin thunderstorms.[92] More organized meteorologicalprojects such as VORTEX2 use an array of sensors, suchas the Doppler on Wheels, vehicles with mounted auto-mated weather stations, weather balloons, and unmannedaircraft to investigate thunderstorms expected to producesevere weather.[93] Lightning is detected remotely usingsensors that detect cloud-to-ground lightning strokes with95 percent accuracy in detection and within 250 metres(820 ft) of their point of origin.[94]

10 Mythology

Thunderstorms strongly influenced many early civiliza-tions. Greeks believed that they were battles waged byZeus, who hurled lightning bolts forged by Hephaestus.Some American Indian tribes associated thunderstormswith the Thunderbird, who they believed was a servant ofthe Great Spirit.[95] The Norse considered thunderstormsto occur when Thor went to fight Jötnar, with the thunderand lightning being the effect of his strikes with the ham-mer Mjölnir. Hinduism recognizes Indra as the god ofrain and thunderstorms. Christian doctrine accepted theideas of Aristotle's original work, called Meteorologica,that winds were caused by exhalations from the Earth andthat fierce stormswere thework ofGod. These ideas werestill within the mainstream as late as the 18th century.[96]

11 Outside of Earth

The clouds of Venus are capable of producing lightningmuch like the clouds on Earth. The lightning rate is atleast half of that on Earth.[97] A thin layer of water cloudsappears to underlie the ammonia layer within Jupiter's at-mosphere, where thunderstorms evidenced by flashes oflightning have been detected. (Water is a polar moleculethat can carry a charge, so it is capable of creating thecharge separation needed to produce lightning.)[98] Theseelectrical discharges can be up to a thousand times aspowerful as lightning on the Earth.[99] The water cloudscan form thunderstorms driven by the heat rising from theinterior.[100]

12 See also

• Barber’s pole

• Continuous gusts

• Convective storm detection

• Hector (storm)

• Severe thunderstorm warning and Severe thunder-storm watch

• Storm train

• Thundersnow

• Tornado warning and Tornado watch

13 References[1] National Weather Service (21 April 2005). “Weather

Glossary – T”. National Oceanic and Atmospheric Ad-ministration. Retrieved 2006-08-23.

12 13 REFERENCES

[2] National Severe Storms Laboratory (September 1992).“tornadoes...Nature’s Most Violent Storms". A PRE-PAREDNESS GUIDE. National Oceanic and AtmosphericAdministration. Retrieved 2008-08-03.

[3] Albert Irvin Frye (1913). Civil engineers’ pocket book: areference-book for engineers, contractors. D. Van Nos-trand Company. p. 462. Retrieved 2009-08-31.

[4] Yikne Deng (2005). Ancient Chinese Inventions. Chi-nese International Press. pp. 112–13. ISBN 978-7-5085-0837-5. Retrieved 2009-06-18.

[5] FMI (2007). “Fog And Stratus – Meteorological PhysicalBackground”. Zentralanstalt für Meteorologie und Geo-dynamik. Retrieved 2009-02-07.

[6] Chris C. Mooney (2007). Storm world: hurricanes, poli-tics, and the battle over global warming. Houghton MifflinHarcourt. p. 20. ISBN 978-0-15-101287-9. Retrieved2009-08-31.

[7] David O. Blanchard (September 1998). “Assess-ing the Vertical Distribution of Convective Avail-able Potential Energy”. Weather and Forecasting(American Meteorological Society) 13 (3): 870–7. Bibcode:1998WtFor..13..870B. doi:10.1175/1520-0434(1998)013<0870:ATVDOC>2.0.CO;2.

[8] Michael H. Mogil (2007). Extreme Weather. New York:Black Dog & Leventhal Publisher. pp. 210–211. ISBN978-1-57912-743-5.

[9] National Severe Storms Laboratory (2006-10-15). “ASevere Weather Primer: Questions and Answers aboutThunderstorms”. National Oceanic and Atmospheric Ad-ministration. Retrieved 2009-09-01.

[10] Gianfranco Vidali (2009). “Rough Values of Various Pro-cesses”. University of Syracuse. Retrieved 2009-08-31.

[11] Pilot’s Web The Aviator’s Journal (2009-06-13).“Structural Icing in VMC”. Retrieved 2009-09-02.

[12] Jon W. Zeitler & Matthew J. Bunkers (March 2005).“Operational Forecasting of Supercell Motion: Re-view and Case Studies Using Multiple Datasets” (PDF).National Weather Service Forecast Office, Riverton,Wyoming. Retrieved 2009-08-30.

[13] TheWeatherWorld 2010 Project (2009-09-03). “VerticalWind Shear”. University of Illinois. Retrieved 2006-10-21.

[14] T. T. Fujita (1985). The Downburst, microburst and mac-roburst: SMRP Research Paper 210.

[15] Glossary ofMeteorology (2009). “Squall line”. AmericanMeteorological Society. Retrieved 2009-06-14.

[16] Glossary of Meteorology (2009). “Prefrontal squall line”.American Meteorological Society. Retrieved 2009-06-14.

[17] University of Oklahoma (2004). “The Norwegian Cy-clone Model” (PDF). Archived from the original (PDF)on September 1, 2006. Retrieved 2007-05-17.

[18] Office of the Federal Coordinator for Meteorology(2008). “Chapter 2: Definitions” (PDF). NOAA. pp. 2–1. Retrieved 2009-05-03.

[19] Glossary of Meteorology (2009). “Bow echo”. AmericanMeteorological Society. Retrieved 2009-06-14.

[20] Glossary of Meteorology (2009). Line echo wave pattern.American Meteorological Society. ISBN 1-878220-34-9.Retrieved 2009-05-03.

[21] Stephen F. Corfidi; Jeffry S. Evans & Robert H. Johns(2015). “About Derechos”. Storm Prediction Center,NCEP, NWS, NOAA Web Site. Retrieved 2015-02-17.

[22] Glossary of Meteorology (2009). Heat burst. AmericanMeteorological Society. ISBN 1-878220-34-9. Retrieved2009-06-14.

[23] “Squall lines and “Shi Hu Feng” – what you want to knowabout the violent squalls hitting Hong Kong on 9 May2005”. Hong Kong Observatory. 17 June 2005. Re-trieved 2006-08-23.

[24] “Supercell Thunderstorms”. Weather World 2010 Project.University of Illinois. October 4, 1999. Retrieved 2006-08-23.

[25] National Weather Service (2005-04-21). “Weather Glos-sary – S”. National Oceanic and Atmospheric Adminis-tration. Retrieved 2007-06-17.

[26] Kim Runk (2009). 1” Hail (.wmv). Silver Spring, Mary-land: NOAA.

[27] National Weather Service Forecast Office, Phoenix, Ari-zona (2009-04-07). “New Hail Criteria”. Retrieved2009-09-03.

[28] Environment Canada Ontario Region (2005-05-24).“Fact Sheet – Summer Severe Weather Warnings”. Re-trieved 2009-09-03.

[29] Glossary of Meteorology (2009). “Mesoscale convectivesystem”. American Meteorological Society. Retrieved2009-06-27.

[30] William R. Cotton; Susan van den Heever & Israel Ji-rak (2003). “Conceptual Models of Mesoscale Convec-tive Systems: Part 9” (PDF). Colorado State University.Retrieved 2008-03-23.

[31] C. Morel & S. Senesi (2002). “A climatology ofmesoscale convective systems over Europe using satel-lite infrared imagery II: Characteristics of Europeanmesoscale convective systems”. Quarterly Journal ofthe Royal Meteorological Society 128 (584): 1973.doi:10.1256/003590002320603494. ISSN 0035-9009.Retrieved 2008-03-02.

[32] Semyon A. Grodsky & James A. Carton (2003-02-15).“The Intertropical Convergence Zone in the South At-lantic and the Equatorial Cold Tongue” (PDF). Universityof Maryland, College Park. Retrieved 2009-06-05.

[33] Michael Garstang; David Roy Fitzjarrald (1999).Observations of surface to atmosphere interactions in thetropics. Oxford University Press US. pp. 40–41. ISBN978-0-19-511270-2.

13

[34] B. Geerts (1998). “Lake Effect Snow”. University ofWyoming. Retrieved 2008-12-24.

[35] E. A. Rasmussen & J. Turner (2003). Polar Lows:Mesoscale Weather Systems in the Polar Regions. Cam-bridge University Press. p. 612. ISBN 978-0-521-62430-5.

[36] Lance F. Bosart & Thomas J. Galarneau, Jr. (2005).“3.5 The Influence of the Great Lakes on Warm SeasonWeather Systems During BAMEX” (PDF). 6th AmericanMeteorological Society Coastal Meteorology Conference.Retrieved 2009-06-15.

[37] William R. Cotton; Susan van den Heever & Israel Jirak(Fall 2003). “Conceptual Models of Mesoscale Convec-tive Systems: Part 9” (PDF). Retrieved 2008-03-23.

[38] Stephen Corfidi (2015-02-04). “MCSMovement and Be-havior (PowerPoint)". National Weather Service, StormPrediction Center. Retrieved 2015-02-18.

[39] NationalWeather Service (2009-09-01). “Types of Thun-derstorms”. National Weather Service Southern RegionHeadquarters. Retrieved 2009-09-03.

[40] National Weather Service Forecast Office, Rapid City,South Dakota (2007-05-15). “The Rapid City Flood of1972”. National Weather Service Central Region Head-quarters. Retrieved 2009-09-03.

[41] David Flower (2008-02-09). “Boscastle Flood 2004”.Tintagel – King Arthur Country. Retrieved 2009-09-03.

[42] Scott, A (2000). “The Pre-Quaternary history of fire”.Palaeogeography Palaeoclimatology Palaeoecology 164:281. doi:10.1016/S0031-0182(00)00192-9.

[43] Vladimir A. Rakov (1999). “Lightning Makes Glass”.University of Florida, Gainesville. Retrieved November7, 2007.

[44] Bruce Getz & Kelli Bowermeister (2009-01-09).“Lightning and Its Hazards”. Hughston Sports MedicineFoundation. Retrieved 2009-09-09.

[45] Charles H. Paxton; J. Colson & N. Carlisle (2008).“P2.13 Florida lightning deaths and injuries 2004–2007”.American Meteorological Society. Retrieved 2009-09-05.

[46] G. E. Likens; W. C. Keene; J. M. Miller & J. N. Gal-loway (1987). “Chemistry of precipitation from a remote,terrestrial site in Australia”. Journal of Geophysical Re-search 92 (13): 299–314. Bibcode:1987JGR....92..299R.doi:10.1029/JA092iA01p00299.

[47] Joel S. Levine; Tommy R. Augustsson; Iris C. Ander-sont; James M. Hoell Jr. & Dana A. Brewer (1984).“Tropospheric sources of NOx: Lightning and biol-ogy”. Atmospheric Environment 18 (9): 1797–1804.doi:10.1016/0004-6981(84)90355-X. PMID 11540827.

[48] Office of Air and Radiation Clean Air Markets Division(2008-12-01). “Effects of Acid Rain – Surface Watersand own Aquatic Animals”. United States EnvironmentalProtection Agency. Retrieved 2009-09-05.

[49] Glossary of Meteorology (2009). “Hailstorm”. AmericanMeteorological Society. Retrieved 2009-08-29.

[50] Geoscience Australia (2007-09-04). “Where does severeweather occur?". Commonwealth of Australia. Archivedfrom the original on 2009-06-21. Retrieved 2009-08-28.

[51] John E. Oliver (2005). Encyclopedia of World Climatol-ogy. Springer. p. 401. ISBN 978-1-4020-3264-6. Re-trieved 2009-08-28.

[52] Dongxia Liu; Guili Feng & Shujun Wu (Febru-ary 2009). “The characteristics of cloud-to-groundlightning activity in hailstorms over northernChina”. Atmospheric Research 91 (2–4): 459–465.doi:10.1016/j.atmosres.2008.06.016.

[53] Damir Počakal; Željko Večenaj & Janez Štalec(2009). “Hail characteristics of different regionsin continental part of Croatia based on influence oforography”. Atmospheric Research 93 (1–3): 516.doi:10.1016/j.atmosres.2008.10.017.

[54] Rene Munoz (2000-06-02). “Fact Sheet on Hail”. Uni-versity Corporation for Atmospheric Research. Retrieved2009-07-18.

[55] Nolan J. Doesken (April 1994). “Hail, Hail, Hail ! TheSummertime Hazard of Eastern Colorado” (PDF). Col-orado Climate 17 (7). Retrieved 2009-07-18.

[56] Federal Aviation Administration (2009). “Hazards”. Re-trieved 2009-08-29.

[57] Damon P. Coppola (2007). Introduction to internationaldisaster management. Butterworth-Heinemann. p. 62.ISBN 978-0-7506-7982-4.

[58] David Orr (2004-11-07). “Giant hail killedmore than 200in Himalayas”. Telegraph Group Unlimited via the In-ternet Wayback Machine. Archived from the original on2005-12-03. Retrieved 2009-08-28.

[59] C. A. Knight and N.C. Knight, 2005: Very Large Hail-stones From Aurora, Nebraska. Bull. Amer. Meteor.Soc., 86, 1773–1781.

[60] Renno, Nilton O. (August 2008). “A thermodynam-ically general theory for convective vortices” (PDF).Tellus A 60 (4): 688–99. Bibcode:2008TellA..60..688R.doi:10.1111/j.1600-0870.2008.00331.x.

[61] Edwards, Roger (2006-04-04). “The Online TornadoFAQ”. Storm Prediction Center. Retrieved 2006-09-08.

[62] “Doppler On Wheels”. Center for Severe Weather Re-search. 2006. Retrieved 2006-12-29.

[63] “Hallam Nebraska Tornado”. Omaha/Valley, NEWeather Forecast Office. 2005-10-02. Retrieved 2006-09-08.

[64] Dr. Terence Meaden (2004). “Wind Scales: Beaufort, T– Scale, and Fujita’s Scale”. Tornado and Storm ResearchOrganisation. Retrieved 2009-09-11.

[65] Storm Prediction Center. “Enhanced F Scale for TornadoDamage”. National Oceanic and Atmospheric Adminis-tration. Retrieved 2009-06-21.

14 13 REFERENCES

[66] “Waterspout”. American Meteorological Society. 2009.Retrieved 2009-09-11.

[67] National Weather Service Forecast Office, Burlington,Vermont (2009-02-03). “15 January 2009: Lake Cham-plain Sea Smoke, Steam Devils, and Waterspout: Chap-ters IV and V”. Eastern Region Headquarters. Retrieved2009-06-21.

[68] Glossary of Meteorology (2009). “Flash Flood”.American Meteorological Society. Retrieved 2009-09-09.

[69] National Weather Service. “Flood Products: What DoThey Mean?". NOAA. Retrieved 23 August 2011.

[70] National Weather Service. “Flash Flood”. NOAA. Re-trieved 23 August 2011.

[71] National Weather Service Forecast Office Columbia,South Carolina (2009-01-27). “Downbursts...”. NationalWeather Service Eastern Region Headquarters. Retrieved2009-09-09.

[72] American Red Cross. “Thunderstorm Safety Checklist”(PDF). American Red Cross. Retrieved 24 August 2011.

[73] National Weather Service Weather Forecast Office.“Thunderstorm”. Severe Weather Preparedness Informa-tion. Albuquerque, NM: NOAA. Retrieved 24 August2011.

[74] Federal Emergency Management Agency.“Thunderstorms and Lightning”. Ready. US De-partment of Homeland Security. Archived from theoriginal on 23 June 2011. Retrieved 24 August 2011.

[75] Federal Emergency Management Agency. “What to DoBefore a Thunderstorm”. US Department of HomelandSecurity. Retrieved 24 August 2011.

[76] “NWS Lightning Safety Myths”. Light-ningsafety.noaa.gov. 2014-06-30. Retrieved 2014-08-20.

[77] “NWS JetStream - Lightning Frequently Asked Ques-tions”. Srh.noaa.gov. 2014-06-28. Retrieved 2014-08-20.

[78] “You're not safer crouching: Six things you didn't knowabout lightning”. LA Times. Retrieved 2014-08-20.

[79] National Geographic Almanac of Geography, ISBN 0-7922-3877-X, page 75.

[80] “How many thunderstorms occur each year?". Thunder-storms. Sky Fire Productions. Retrieved 2006-08-23.

[81] National Weather Service JetStream (2008-10-08).“Tropical Cyclone Hazards”. National Weather ServiceSouthern Region Headquarters. Retrieved 2009-08-30.

[82] David Roth. “Unified Surface Analysis Manual” (PDF).Hydrometeorological Prediction Center. Retrieved 2006-10-22.

[83] Office of the Federal Coordinator for Meteorology (2001-06-07). “National Severe Local Storms Operations Plan –Chapter 2” (PDF). Department of Commerce. Retrieved2006-08-23.

[84] Bill Giles O.B.E (2004-09-01). “Lightning”. BBC.Archived from the original on March 23, 2008. Retrieved2008-06-29.

[85] Goddard Space Flight Center (2003-01-14). “Lightningreally does hit more than twice”. National Aeronauticsand Space Administration. Retrieved 2009-09-09.

[86] Glossary of Meteorology (2009). “Ball Lightning”.American Meteorological Society. Retrieved 2009-09-09.

[87] Glossary of Meteorology (2009). “Lightning”. AmericanMeteorological Society. Retrieved 2009-09-09.

[88] Glossary of Meteorology (2009). “Heat Lightning”.American Meteorological Society. Retrieved 2009-09-09.

[89] NASA – NASA’s Fermi Catches Thunderstorms HurlingAntimatter into Space

[90] Ouellette, Jennifer (January 13, 2011). “Fermi Spots An-timatter in Thunderstorms”. Discovery News. Retrieved16 January 2011.

[91] Alan Moller (2003-03-05). “Storm Chase Ethics”. Re-trieved 2009-09-09.

[92] Florida Institute of Technology (2009-06-02). “Scientistsuse high-energy particles from space to probe thunder-storms”. Retrieved 2009-09-09.

[93] VORTEX2 (2009). “What is VORTEX2?". Retrieved2009-09-09.

[94] Peter P. Neilley & R. B. Bent (2009). “An Overviewof the United States Precision Lightning Network (US-PLN)". American Meteorological Society Fourth Con-ference on the Meteorological Applications of LightningData. Retrieved 2009-09-09.

[95] Obsidian’s Lair (2008-06-11). “A Haudenosaunee Pan-theon”. Corecomm. Retrieved 2009-09-09.

[96] JohnD. Cox (2002). StormWatchers. JohnWiley& Sons,Inc. p. 7. ISBN 0-471-38108-X.

[97] Russell, S. T.; Zhang, T.L.; Delva, M.; et al.(2007). “Lightning on Venus inferred fromwhistler-mode waves in the ionosphere”. Nature450 (7170): 661–662. Bibcode:2007Natur.450..661R.doi:10.1038/nature05930. PMID 18046401.

[98] Elkins-Tanton, Linda T. (2006). Jupiter and Saturn. NewYork: Chelsea House. ISBN 0-8160-5196-8.

[99] Watanabe, Susan, ed. (February 25, 2006). “SurprisingJupiter: Busy Galileo spacecraft showed jovian system isfull of surprises”. NASA. Retrieved 2007-02-20.

[100] Kerr, Richard A. (2000). “Deep, Moist Heat DrivesJovian Weather”. Science 287 (5455): 946–947.doi:10.1126/science.287.5455.946b. Retrieved 2007-02-24.

15

14 Further reading

• Burgess, D. W., R. J. Donaldson Jr., and P. R.Desrochers, 1993: Tornado detection and warningby radar. The Tornado: Its Structure, Dynamics,Prediction, and Hazards, Geophys. Monogr., No.79, American Geophysical Union, 203–221.

• Corfidi, S. F., 1998: Forecasting MCSmode and mo-tion. Preprints 19th Conf. on Severe Local Storms,American Meteorological Society, Minneapolis,Minnesota, pp. 626–629.

• Davies, J. M., 2004: Estimations of CIN and LFCassociated with tornadic and nontornadic supercells.Wea. Forecasting, 19, 714–726.

• Davies, J. M., and R. H. Johns, 1993: Some windand instability parameters associated with strong andviolent tornadoes. Part I: Helicity and mean shearmagnitudes. The Tornado: Its Structure, Dynam-ics, Prediction, and Hazards (C. Church et al., Eds.),Geophysical Monograph 79, American GeophysicalUnion, 573–582.

• David, C. L. 1973: An objective of estimating theprobability of severe thunderstorms. Preprint Eightconference of Severe Local Storms. Denver, Col-orado, American Meteorological Society, 223–225.

• Doswell, C.A., III, D. V. Baker, and C. A. Liles,2002: Recognition of negative factors for severeweather potential: A case study. Wea. Forecasting,17, 937–954.

• Doswell, C.A., III, S.J. Weiss and R.H. Johns(1993): Tornado forecasting: A review. The Tor-nado: Its Structure, Dynamics, Prediction, and Haz-ards (C. Church et al., Eds), Geophys. Monogr. No.79, American Geophysical Union, 557–571.

• Johns, R. H., J. M. Davies, and P. W. Leftwich,1993: Some wind and instability parameters asso-ciated with strong and violent tornadoes. Part II:Variations in the combinations of wind and instabil-ity parameters. The Tornado: Its Structure, Dynam-ics, Prediction and Hazards, Geophys. Mongr., No.79, American Geophysical Union, 583–590.

• Evans, Jeffry S.,: Examination of Derecho Environ-ments Using Proximity Soundings. NOAA.gov

• J. V. Iribarne and W.L. Godson, Atmospheric Ther-modynamics, published by D. Reidel PublishingCompany, Dordrecht, the Netherlands, 1973

• M. K. Yau and R. R. Rogers, Short Coursein Cloud Physics, Third Edition, published byButterworth-Heinemann, January 1, 1989, EAN9780750632157 ISBN 0-7506-3215-1

15 External links• Thunderstorm lightning in realtime – Europe

• Anatomy of a thunderstorm

• Electronic Journal of Severe Storms Meteorology

• Social & Economic Costs of Thunderstorms &HighWinds NOAA Economics

• Thunderstorm photography in Germany

• Air traffic control display at an airport of aircraftavoiding thunderstorm

16 16 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

16 Text and image sources, contributors, and licenses

16.1 Text

• Thunderstorm Source: https://en.wikipedia.org/wiki/Thunderstorm?oldid=693613910 Contributors: Magnus Manske, Bryan Derksen,The Anome, Stephen Gilbert, -- April, Scipius, SimonP, Luckymama58, Frecklefoot, Ubiquity, Lir, Michael Hardy, Fuzzie, Gabbe, Ixfd64,Arpingstone, SebastianHelm, Ellywa, Ahoerstemeier, Djaquay, Julesd, Andres, CimonAvaro, Hike395, RadarCzar, Emperorbma, Ike9898,Dysprosia, WhisperToMe, Jeffrey Smith, Samsara, Metasquares, Slawojarek, Cornellier, Cedars, Timvasquez, MPF, Gtrmp, Wonder al,SwissMoomin, Peruvianllama, Everyking, Utcursch, Beland, OverlordQ, Herrick~enwiki, Johnwalton, Famartin, Mike Rosoft, Discospin-ster, Solitude, Rich Farmbrough, Andros 1337, Vsmith, Edibobb, Smyth, Xezbeth, GregBenson, Bender235, ESkog, Kbh3rd, JoeSmack,El C, Edward Z. Yang, Tom, Bobo192, Grue, Fir0002, Func, Evolauxia, BrokenSegue, Cohesion, MWS, Helix84, Jakew, Alansohn, Gary,Lightdarkness, Snowolf, Wtmitchell, Skatebiker, Itsmine, Gene Nygaard, Dan100, Mahanga, Shimeru, MONGO, Hard Raspy Sci, Way-ward, Icydid, Enzo Aquarius, Saperaud~enwiki, Rjwilmsi, Angusmclellan, Koavf, Wiktator, Vary, Tangotango, The wub, VanishedUsersdu9aya9fs465465, Yamamoto Ichiro, FlaBot, SchuminWeb, Gordin~enwiki, Harmil, Nivix, RexNL, Gurch, Leslie Mateus, Terrx, Pbu-lises, Srleffler, DVdm, NoAccount, Kummi, Wavelength, Sceptre, Jimp, Epolk, Stephenb, Gaius Cornelius, Eleassar, Pseudomonas, Nawl-inWiki, EWS23, Icelight, Retired username, CrazyC83, Cholmes75, Ravedave, Raven4x4x, Dbfirs, DeadEyeArrow, Psy guy, Bota47,JonathanLamb, Wknight94, Bidiot, Ageekgal, Theda, E Wing, Nemu, Dspradau, RenamedUser jaskldjslak904, Tim R, Staxringold,Katieh5584, Roke, Jro660, Medicinematt, Suburbancow, Sardanaphalus, FearTec, SmackBot, KnowledgeOfSelf, Hydrogen Iodide, Mel-choir, NorthernFire, WilyD, Cormallen, Momoko, Jrockley, Teimu.tm, Frymaster, Gaff, Xaosflux, Gilliam, Ohnoitsjamie, Hmains, Skizzik,Martial Law, Rmosler2100, Lovecz, Bidgee, Keegan, Sirex98, Raymond arritt, EncMstr, SchfiftyThree, Zinneke, Colonies Chris, Zsinj,Dethme0w, Vulcanstar6, OrphanBot, Snowmanradio, Rrburke, Homestarmy, Addshore, Jmlk17, E. Sn0 =31337=, Salt Yeung, The PIPE,Kuzaar, Jidanni, This user has left wikipedia, Mgiganteus1, Scetoaux, Pflatau, Thegreatdr, TheMan in Question, 16@r, Pierre cb, Special-T,Burynew, Mr Stephen, ImagineWizard, P199, Peter Horn, Laggard, KJS77, Levineps, Iridescent, The Giant Puffin, Paul venter, Tmangray,Devin122, Dragonix, Igoldste, Civil Engineer III, Courcelles, The tyr3nt, Tawkerbot2, Annihilatenow, Xcentaur, JForget, Tanthalas39, Alejrb, BennyD, JohnCD, Kylu, NickW557, Jonathan8964, ShelfSkewed, Orca1 9904, Natasha2006, Gogo Dodo, STV0726, ST47, Agne27,7H3 P0WN463, Tawkerbot4, DumbBOT, Sp, Ecarrel, WxGopher, Thijs!bot, Epbr123, Pajz, Ultimus, Oliver202, John254, MassimoMac-coni, Dfrg.msc, Philippe, Natalie Erin, Mentifisto, SuperCow, AntiVandalBot, Mjl72, Seaphoto, Opelio, Jj137, Wikibryce, PhJ, Danger,Spencer, Lonestar662p3, Storkk, Myanw, Uusitunnus, JAnDbot, MER-C, Shorvath, Arch dude, Sophie means wisdom, TheOtherSiguy,Roleplayer, Alastair Haines, Acroterion, Guerrid, Canjth, Bongwarrior, VoABot II, JNW, Think outside the box, Nahog, Avicennasis,Catgut, Theroadislong, Allstarecho, DerHexer, JaGa, Nathan Hall, Hbent, Calltech, Hdt83, MartinBot, Vicpeters, Arjun01, Lelandrb,Roastytoast, R'n'B, CommonsDelinker, AlexiusHoratius, Theonlysilentbob, Lilac Soul, Themanfromsiam, Paranomia, J.delanoy, Astro-Hurricane001, Nigholith, Jesant13, 12dstring, Fleiger, Lttlalb277, Janus Shadowsong, Jeepday, Vanished User 4517, NewEnglandYankee,SJP, Kraftlos, Cmichael, KylieTastic, Cometstyles, Warlordwolf, Vanished user 39948282, Inter16, TWCarlson, WinterSpw, TheNewPho-bia, Catluver101, CardinalDan, Idioma-bot, Wikieditor06, Lights, VolkovBot, Error9312, TreasuryTag, CWii, Jlaramee, Mrh30, Trex21,WarddrBOT, Aesopos, Philip Trueman, Spurius Furius Fusus, DoorsAjar, TXiKiBoT, Oshwah, AlexRampaul, Altruism, Vipinhari, Qxz,Piperh, DennyColt, CanOfWorms, Solo1234, LeaveSleaves, Ben Ward, Saturn star, Kwb8988, BabylonClo, Spinningspark, GangstersPeteWentz, Monty845, Estanoir, Nye229, Yartrebo, Alexandre Bouthors, SevereIdaho, Thebisch, The Random Editor, SieBot, TiddlyTom, Scarian, Mr Share, Hertz1888, Gerakibot, Yintan, Tiptoety, JD554, Fujita, Smartjason, Oxymoron83, Antonio Lopez, KPH2293,Bagatelle, Shiragiku, Lightmouse, Ks0stm, Dj mike89, StaticGull, Wuhwuzdat, Hamiltondaniel, Neo., Denisarona, Muhends, ImageRe-movalBot, Martarius, ClueBot, LAX, CarolSpears, The Thing That Should Not Be, Southern Illinois SKYWARN, Rjd0060, BookeWorm,Hippostud, UserDoe, Farras Octara, Xenon54, Blanchardb, RafaAzevedo, Pyrolysis, Oobflyer, Excirial, Gnome de plume, Jusdafax, Tony-Ballioni, ErebusMorgaine, Jerry Zhang, Lartoven, Combat1019, Povertypop the 7th, JamieS93, TheRedPenOfDoom, 7&6=thirteen, Yeah-babies, Thingg, Accas1, Aitias, Adammacia, Scalhotrod, Versus22, SoxBot III, Dollsworth, DumZiBoT, Guppy22, Nooristani, Death horn5, Jax 0677, BodhisattvaBot, Quellyn, Qfl247, Jimmydeguara, Sickler77, WikiDao, Me, Myself, and I, Miagirljmw14, Cyclonebiskit,Bhockey10, Bonzeemer, Addbot, L33tb0b, ConCompS, AVand, Chalkman123, Jojhutton, Albamhandae, Leszek Jańczuk, Noozgroop,Dog1990, MrOllie, BepBot, SamatBot, AtheWeatherman, Aktsu, Tyw7, Itfc+canes=me, Ehrenkater, Rehman, Tide rolls, Verbal, Lightbot,Luckas Blade, Greyhood, HerculeBot, Rafikimambo, Legobot, Luckas-bot, Yobot, 2D, Bunnyhop11, Tohd8BohaithuGh1, TaBOT-zerem,KingScreamer, Naudefjbot~enwiki, Ojay123, Victoriaearle, Guy1890, Tromba206, Patriiick, KamikazeBot, Jalantucker, IW.HG, Tem-podivalse, Synchronism, AnomieBOT, Andrewrp, AmritasyaPutra, IncidentalPoint, Jim1138, IRP, Greenbreen, AdjustShift, Flewis, Gi-ants27, Materialscientist, The High Fin SpermWhale, Citation bot, Maxis ftw, S h i v a (Visnu), Sionus, Phthinosuchusisanancestor, Capri-corn42, Matt7771, Jmundo, KrisBogdanov, Coretheapple, Danielgibsonfor3, Wuuh, Smallman12q, Afirex, Sandcherry, FrescoBot, Origi-nalwana, VS6507, Michael93555, Mr. Comodor, Galorr, Fgkljlgjfkjg, Ddjdjd, Citation bot 1, MarB4, Redrose64, JIK1975, Pinethicket,Ponycide, Back dancer, Tom.Reding, CalmerWaters, Tinton5, Supportstorm, RandomStringOfCharacters, Full-date unlinking bot, Knowl-edgeRequire, White Shadows, Getheren, FoxBot, Trappist the monk, Gamemusicmaker, D climacus, GooseYArd, Lotje, Callanecc, Vre-nator, Joshuaxkimchi, Papizan, GGT, Smarty02, Diannaa, Mttcmbs, Titlicker, Tbhotch, Reach Out to the Truth, Nevin.williams, Hornlitz,Bento00, DexDor, Will research for food, Jackehammond, Regancy42, DASHBot, EmausBot, John of Reading, WikitanvirBot, Immu-nize, Fishmander, Ks5stm, Tommy2010, Christlover1, Stormchaser89, Lou1986, AsceticRose, ZéroBot, John Cline, Ida Shaw, NicatronTg,The Lord of the Allosaurs, H3llBot, Scott9999999, Christina Silverman, Kilopi, MonoAV, Donner60, Epicstonemason, GrayFullbuster,DASHBotAV, Petrb, ClueBot NG, Smtchahal, Jack Greenmaven, CocuBot, This lousy T-shirt, Wetassassass, Sleddog116, Movses-bot,Snotbot, Frietjes, Go Phightins!, Jeroenelf, Helpful Pixie Bot, HMSSolent, Bcormier1234, Bibcode Bot, Lowercase sigmabot, BG19bot,Lexicurry, Pine, Harmonicsonic, Nochoje, TCN7JM, Christianmairdrain, S9p9a9r9k, Wiki13, Sportyrod, Ashley79746, IraChesterfield,Zweatherboy, Altaïr, CitationCleanerBot, Deonking, Physicsch, Sarah.awesome, BattyBot, Brohnhdon, Bob1234567890bob1234567890,XXmYrAnNdAxX, Cyberbot II, Phénomènes Naturels, Arcandam, Lexter John, Kanghuitari, Lakshya (razor), Pcdmint, Rburke5786, Lu-gia2453, 13332O572O86142, Great Purple Way, Little green rosetta, Tellan7, Joshua.murphy2012, Grayowl3, Sosthenes12, Maddiebell-bee, Ethanmunkee, Passw, Passwo, Dustin V. S., Johnytheapple, NYBrook098, Pokpok52431, WxBot, Kharkiv07, Miniguy222, Glavtech,Jianhui67, Frogger48, Kaptinkrill123, Coastwisenav, CurtismagnusA, Monkbot, Kinetic37, JustMeAndOnlyMe, JustThinkOfUs, Thel-ogoontherun, Iamahashtag, Julietdeltalima, Coconutporkpie, LolBean21, Luke49237, Mada126, Rb119, VTDK, Kiki715, Griffinstorm,Ha1704, Idontcare45678, Ericgrandpre15, Brodie Flynn, Dcasey98, Writer Mania and Anonymous: 932

16.2 Images 17

16.2 Images• File:8402_STS41B_Challenger_Thunderstorms_over_Brazil.JPG Source: https://upload.wikimedia.org/wikipedia/commons/5/5b/

8402_STS41B_Challenger_Thunderstorms_over_Brazil.JPG License: Public domain Contributors: http://eol.jsc.nasa.gov/sseop/EFS/photoinfo.pl?PHOTO=STS41B-41-2347 Original artist: NASA

• File:Anvil_shaped_cumulus_panorama_edit_crop.jpg Source: https://upload.wikimedia.org/wikipedia/commons/9/98/Anvil_shaped_cumulus_panorama_edit_crop.jpg License: GFDL 1.2 Contributors: Own work Original artist:fir0002 | flagstaffotos.com.au

• File:Blitze_IMGP6376_wp.jpg Source: https://upload.wikimedia.org/wikipedia/commons/a/a0/Blitze_IMGP6376_wp.jpg License:FAL Contributors: Own work Original artist: smial (<a href='//commons.wikimedia.org/wiki/User_talk:Smial' title='User talk:Smial'>talk</a>)

• File:Bogota_hailstorm.jpg Source: https://upload.wikimedia.org/wikipedia/commons/2/2b/Bogota_hailstorm.jpg License: CC-BY-SA-3.0 Contributors: en:Image:Bogota hailstorm.jpg Original artist: Ju98 5

• File:CAPE_vs_SHEAR.png Source: https://upload.wikimedia.org/wikipedia/commons/6/6a/CAPE_vs_SHEAR.png License: CC-BY-SA-3.0 Contributors: Own work Original artist: Pierre_cb

• File:Chaparral_Supercell_2.JPG Source: https://upload.wikimedia.org/wikipedia/commons/2/20/Chaparral_Supercell_2.JPG License:Public domain Contributors: {{[http://www.srh.noaa.gov/elp/swww/v8n1/Chaparral%20Supercell%202.JPG%7D%7D http://www.srh.noaa.gov/elp/swww/v8n1/Chaparral%20Supercell%202.JPG}}] si c'est une photo personnelle, sinon le lien vers la page internet d'où ellevient Original artist: Greg Lundeen

• File:Commons-logo.svg Source: https://upload.wikimedia.org/wikipedia/en/4/4a/Commons-logo.svg License: ? Contributors: ? Originalartist: ?

• File:Cumulonimbus_Over_Niagara_Falls.JPG Source: https://upload.wikimedia.org/wikipedia/commons/8/83/Cumulonimbus_Over_Niagara_Falls.JPG License: CC BY-SA 3.0 Contributors: Own work Original artist: The Lord of the Allosaurs

• File:Cumulus_clouds_in_fair_weather.jpeg Source: https://upload.wikimedia.org/wikipedia/commons/b/b5/Cumulus_clouds_in_fair_weather.jpeg License: CC BY-SA 2.0 Contributors: legacy.openphoto.net Original artist: Michael Jastremski

• File:Downburst_damage.jpg Source: https://upload.wikimedia.org/wikipedia/commons/0/00/Downburst_damage.jpg License: Publicdomain Contributors: Image from the downburst case of July 27th 1998 Original artist: Todd Shea, La Crosse National Weather ServiceOffice (NOAA)

• File:Edit-clear.svg Source: https://upload.wikimedia.org/wikipedia/en/f/f2/Edit-clear.svg License: Public domain Contributors: TheTango! Desktop Project. Original artist:The people from the Tango! project. And according to the meta-data in the file, specifically: “Andreas Nilsson, and Jakub Steiner (althoughminimally).”

• File:F5_tornado_Elie_Manitoba_2007.jpg Source: https://upload.wikimedia.org/wikipedia/commons/9/98/F5_tornado_Elie_Manitoba_2007.jpg License: CC-BY-SA-3.0 Contributors: Transferred from en.wikipedia; transferred to Commons by User:Gump Stumpusing CommonsHelper. Original artist: Justin Hobson (Justin1569 at en.wikipedia)

• File:FoggDam-NT.jpg Source: https://upload.wikimedia.org/wikipedia/commons/0/0c/FoggDam-NT.jpg License: CC BY 3.0 Contrib-utors: Own work Original artist: Bidgee

• File:Great_Lakes_Waterspouts.jpg Source: https://upload.wikimedia.org/wikipedia/en/4/41/Great_Lakes_Waterspouts.jpg License:PD Contributors:http://www.vos.noaa.gov/MWL/dec_04/waterspout.shtml Original artist:National Oceanic and Atmospheric Administration

• File:How_thunderstorms_launch_particle_beams_into_space_300dpi.jpg Source: https://upload.wikimedia.org/wikipedia/commons/e/e1/How_thunderstorms_launch_particle_beams_into_space_300dpi.jpg License: Public domain Contributors: press releaseTerrestrial Gamma-ray Flashes Create Antimatterdirect Original artist: NASA/Goddard Space Flight Center.

• File:Kings_Christian_Church_carpark_Flooded.jpg Source: https://upload.wikimedia.org/wikipedia/commons/7/78/Kings_Christian_Church_carpark_Flooded.jpg License: CC BY-SA 3.0 Contributors: Own work Original artist: Bidgee

• File:LightningCNP.ogg Source: https://upload.wikimedia.org/wikipedia/commons/d/d6/LightningCNP.ogg License: CC BY-SA 3.0Contributors: Transferred from en.wikipedia; transferred to Commons by User:Innotata using CommonsHelper.Original artist: Qfl247 at en.wikipedia

• File:Lightning_in_Arlington.jpg Source: https://upload.wikimedia.org/wikipedia/commons/6/69/Lightning_in_Arlington.jpg License:CC-BY-SA-3.0 Contributors: Digital photo taken by User:Postdlf Original artist: Postdlf

• File:MCCaug0220060545z.gif Source: https://upload.wikimedia.org/wikipedia/commons/9/94/MCCaug0220060545z.gif License: Pub-lic domain Contributors: ftp://eclipse.ncdc.noaa.gov/pub/isccp/b1/.D2790P/images/2006/214/Img-2006-08-02-06-GOE-12-IR.jpgOrig-inal artist: ?

• File:Single-cell_Thunderstorm_in_a_No-shear_Environment..jpg Source: https://upload.wikimedia.org/wikipedia/commons/2/27/Single-cell_Thunderstorm_in_a_No-shear_Environment..jpg License: CCBY-SA 4.0Contributors: OwnworkOriginal artist: Griffinstorm

• File:Sturmfront_auf_Doppler-Radar-Schirm.jpg Source: https://upload.wikimedia.org/wikipedia/commons/0/0c/Sturmfront_auf_Doppler-Radar-Schirm.jpg License: Public domain Contributors: ? Original artist: ?

• File:Thunderhead.anvil.jpg Source: https://upload.wikimedia.org/wikipedia/commons/5/55/Thunderhead.anvil.jpg License: Public do-main Contributors: I took this image on 9.16.2006--MONGO 05:19, 1 September 2007 (UTC) Original artist: MONGO

• File:Thunderstorm_Updraft.JPG Source: https://upload.wikimedia.org/wikipedia/commons/0/09/Thunderstorm_Updraft.JPG Li-cense: CC BY-SA 4.0 Contributors: Own work Original artist: Griffinstorm

18 16 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• File:Thunderstorm_formation.jpg Source: https://upload.wikimedia.org/wikipedia/commons/c/c8/Thunderstorm_formation.jpg Li-cense: Public domain Contributors:

• Tstorm-tcu-stage.jpg Original artist: Tstorm-tcu-stage.jpg: NOAA• File:Thunderstorm_in_sydney_2000x1500.png Source: https://upload.wikimedia.org/wikipedia/commons/1/19/Thunderstorm_in_

sydney_2000x1500.png License: CC BY 3.0 Contributors: Own work by the original uploader Original artist: Patriiick• File:Thunderstorm_over_Corfu.jpg Source: https://upload.wikimedia.org/wikipedia/commons/3/3d/Thunderstorm_over_Corfu.jpgLicense: CC BY 2.0 Contributors: Flickr: Lightning Strikes Original artist: Simon Q

• File:Thunderstorm_over_Wagga_Wagga.jpg Source: https://upload.wikimedia.org/wikipedia/commons/8/8a/Thunderstorm_over_Wagga_Wagga.jpg License: CC-BY-SA-3.0 Contributors: Transferred from en.wikipedia to Commons. Original artist: Bidgee at EnglishWikipedia

16.3 Content license• Creative Commons Attribution-Share Alike 3.0