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Thunderstorm |
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| Look up thunderstorm in Wiktionary, the free dictionary.Airflow diagrams showing three stages of a thunderstorm life cycle.All thunderstorms, regardless of type, go through three stages: the cumulus stage, the mature stage, and the dissipation stage.Cumulus stage
The first stage of thunderstorm is the cumulus stage, or developing stage.In this stage, masses of moisture are lifted upwards into the atmosphere.The trigger for this lift can be insolation heating the ground producing thermals, areas where two winds converge forcing air upwards, or where winds blow over terrain of increasing elevation.As the water vapor condenses into liquid, latent heat is released which warms the air, causing it to become less dense than the surrounding dry air.The air tends to rise in an updraft through the process of convection (hence the term convective precipitation).In the mature stage of a thunderstorm, the warmed air continues to rise until it reaches existing air which is warmer, and the air can rise no further.The air is instead forced to spread out, giving the storm a characteristic anvil shape.The water droplets coalesce into heavy droplets and freeze to become ice particles.If the updraft is strong enough, the droplets are held aloft long enough to be so large that they do not melt completely and fall as hail.While updrafts are still present, the falling rain creates downdrafts as well.The simultaneous presence of both an updraft and downdrafts marks the mature stage of the storm, and during this stage considerable internal turbulence can occur in the storm system, which sometimes manifests as strong winds, severe lightning, and even tornadoes.In certain cases however, even with little wind shear, if there is enough atmospheric support and instability in place for the thunderstorm to feed on, it may even maintain its mature stage a bit longer than most storms.Dissipating stage
In the dissipation stage, the thunderstorm is dominated by the downdraft.The downdraft will push down out of the thunderstorm, hit the ground and spread out.The cool air carried to the ground by the downdraft cuts off the inflow of the thunderstorm, the updraft disappears and the thunderstorm will dissipate.There are four main types of thunderstorms: single cell, multicell, squall line (also called multicell line) and supercell.Single cell
This term technically applies to a single thunderstorm with one main updraft.Within a cluster of thunderstorms, the term "cell" refers to each separate principal updraft.Thunderstorm cells can and do form in isolation to other cells.Such storms are rarely severe and are a result of local atmospheric instability; hence the term "air mass thunderstorm".These are the typical summer thunderstorm in many temperate locales.They also occur in the cool unstable air which often follows the passage of a cold front from the sea during winter.Multicell lines
Multicell line storms, commonly referred to as "squall lines", occur when multi cellular storms form in a line rather than clusters.In fact, most tornadoes occur from this kind of thunderstorm.Though a funnel cloud or tornado indicates the presence of a severe thunderstorm, a tornado warning would then be issued in place of a severe thunderstorm warning.Severe thunderstorms can occur from any type of thunderstorm, however multicell and squall lines represent the most common forms.Prior to the discovery of the MCS phenomenon, the individual thunderstorms were thought of as independent entities, each being effectively impossible to predict.The MCS is amenable to forecasting, and a meteorologist can predict with high accuracy the percentage of the MCS that will be affected by thunderstorms.However, the meteorologist still cannot predict exactly where each thunderstorm will occur within the MCS.Energy
If the quantity of water that is condensed in and subsequently precipitated from a cloud is known, then the total energy of a thunderstorm can be calculated.Thunderstorms occur throughout the world, even in the polar regions, with the greatest frequency in tropical rainforest areas, where they may occur nearly daily.Thunderstorms are associated with the various monsoon seasons around the globe, and they populate the rainbands of all tropical cyclones.Thunderstorms are rare in polar regions because of cold surface temperatures.The most powerful and dangerous severe thunderstorms also occur over the United States, particularly in the Midwest and the southern states.Sacramento and San Joaquin Valleys of California.During the summer, violent thunderstorms are an almost daily occurrence over central and southern parts of the state.In more contemporary times, thunderstorms have taken on the role of a curiosity.Every spring, storm chasers head to the Great Plains of the United States and the Canadian Prairies to explore the visual and scientific aspects of storms and tornadoes.Lightning is an electrical discharge that occurs in a thunderstorm.Lightning occurs when an electrical charge is built up within a cloud.Although the lightning is extremely hot, the short duration makes it not necessarily fatal.There are several kinds of lightning.Cloud to ground lightning is when a bolt of lightning from a cloud strikes the ground.This form poses the greatest threat to life and property.Dry lightning is a misnomer which refers to a thunderstorm whose precipitation does not reach the ground.Mythology
Thunderstorms have had a lasting and powerful influence on early civilizations.Thunderstorms were associated with the Thunderbirds, held by Native Americans to be a servant of the Great Spirit.National Weather Service (21 April 2005).Weather World 2010 Project.How many thunderstorms occur each year?.Estimations of CIN and LFC associated with tornadic and nontornadic supercells.An objective of estimating the probability of severe thunderstorms.The Tornado: Its Structure, Dynamics, Prediction, and Hazards (C.Examination of Derecho Environments Using Proximity Soundings.The Tornado: Its Structure, Dynamics, Prediction and Hazards, Geophys.This page was last modified 03:14, 18 January 2008.Look up thunderstorm in Wiktionary, the free dictionary.Airflow diagrams showing three stages of a thunderstorm life cycle.All thunderstorms, regardless of type, go through three stages: the cumulus stage, the mature stage, and the dissipation stage.Depending on the conditions present in the atmosphere, these three stages can take anywhere from 20 minutes to several hours to occur.Cumulus stage
The first stage of thunderstorm is the cumulus stage, or developing stage.In this stage, masses of moisture are lifted upwards into the atmosphere.As the water vapor condenses into liquid, latent heat is released which warms the air, causing it to become less dense than the surrounding dry air.In the mature stage of a thunderstorm, the warmed air continues to rise until it reaches existing air which is warmer, and the air can rise no further.Often this 'cap' is the tropopause.In certain cases however, even with little wind shear, if there is enough atmospheric support and instability in place for the thunderstorm to feed on, it may even maintain its mature stage a bit longer than most storms.Dissipating stage
In the dissipation stage, the thunderstorm is dominated by the downdraft.The downdraft will push down out of the thunderstorm, hit the ground and spread out.The cool air carried to the ground by the downdraft cuts off the inflow of the thunderstorm, the updraft disappears and the thunderstorm will dissipate.There are four main types of thunderstorms: single cell, multicell, squall line (also called multicell line) and supercell.Single cell
This term technically applies to a single thunderstorm with one main updraft.Within a cluster of thunderstorms, the term "cell" refers to each separate principal updraft.Thunderstorm cells can and do form in isolation to other cells.Such storms are rarely severe and are a result of local atmospheric instability; hence the term "air mass thunderstorm".These are the typical summer thunderstorm in many temperate locales.They also occur in the cool unstable air which often follows the passage of a cold front from the sea during winter.Bow echoes can form within squall lines, bringing with them even higher winds.An unusually powerful type of squall line called a derecho occurs when an intense squall line travels for several hundred miles, often leaving widespread damage over thousands of square miles.Occasionally, squall lines also form near the outer rain band of tropical cyclones.In fact, most tornadoes occur from this kind of thunderstorm.Please help improve this article or section by expanding it.Though a funnel cloud or tornado indicates the presence of a severe thunderstorm, a tornado warning would then be issued in place of a severe thunderstorm warning.Severe thunderstorms can occur from any type of thunderstorm, however multicell and squall lines represent the most common forms.Prior to the discovery of the MCS phenomenon, the individual thunderstorms were thought of as independent entities, each being effectively impossible to predict.The MCS is amenable to forecasting, and a meteorologist can predict with high accuracy the percentage of the MCS that will be affected by thunderstorms.However, the meteorologist still cannot predict exactly where each thunderstorm will occur within the MCS.Energy
If the quantity of water that is condensed in and subsequently precipitated from a cloud is known, then the total energy of a thunderstorm can be calculated.Thunderstorms occur throughout the world, even in the polar regions, with the greatest frequency in tropical rainforest areas, where they may occur nearly daily.Bogor on Java, Indonesia or Singapore.Thunderstorms are associated with the various monsoon seasons around the globe, and they populate the rainbands of all tropical cyclones.Thunderstorms are rare in polar regions because of cold surface temperatures.The most powerful and dangerous severe thunderstorms also occur over the United States, particularly in the Midwest and the southern states.These storms can produce large hail and powerful tornadoes.Sacramento and San Joaquin Valleys of California.Probably the most thunderous region outside of the Tropics is Florida.During the summer, violent thunderstorms are an almost daily occurrence over central and southern parts of the state.In more contemporary times, thunderstorms have taken on the role of a curiosity.Lightning is an electrical discharge that occurs in a thunderstorm.Lightning occurs when an electrical charge is built up within a cloud.When a large enough charge is built up, a large discharge will occur and can be seen as lightning.The temperature of a lightning bolt can be hotter than the surface of the sun.Although the lightning is extremely hot, the short duration makes it not necessarily fatal.Ground to cloud lightning is when a lightning bolt is induced from the ground to the cloud.Ball lightning is extremely rare and has no known scientific explanation.It is seen in the form of a 20 to 200 centimeter ball.Dry lightning is a misnomer which refers to a thunderstorm whose precipitation does not reach the ground.Mythology
Thunderstorms have had a lasting and powerful influence on early civilizations.Romans thought them to be battles waged by Jupiter, who hurled lightning bolts forged by Vulcan.Thunderstorms were associated with the Thunderbirds, held by Native Americans to be a servant of the Great Spirit.National Weather Service (21 April 2005).Hong Kong Observatory (17 June 2005).Weather World 2010 Project.How many thunderstorms occur each year?.Johns, 1993: Some wind and instability parameters associated with strong and violent tornadoes.Part I: Helicity and mean shear magnitudes.An objective of estimating the probability of severe thunderstorms.Johns (1993): Tornado forecasting: A review.Examination of Derecho Environments Using Proximity Soundings.How Can I Protect Myself From a Thunderstorm or Lightning?All thunderstorms are dangerous.Every thunderstorm produces lightning.In the United States, an average of 300 people are injured and 80 people are killed each year by lightning.Dry thunderstorms that do not produce rain that reaches the ground are most prevalent in the western United States.They may occur singly, in clusters, or in lines.Some of the most severe occur when a single thunderstorm affects one location for an extended time.Thunderstorms typically produce heavy rain for a brief period, anywhere from 3 0 minutes to an hour.Warm, humid conditions are highly favorable for thunderstorm development."Heat lightning" is actually lightning from a thunderstorm too far away for thunder to be heard.However, the storm may be moving in your direction!Your chances of being struck by lightning are estimated to be 1 in 600,000, but could be reduced even further by following safety precautions.How Can I Protect Myself From a Thunderstorm or Lightning?FEMA 500 C Street SW, Washington, D.What Makes a Severe Thunderstorm?These are known as severe thunderstorms.Where Are Severe Thunderstorms Likely to Occur?On average, the interior sections of central Florida receive the most thunderstorms with nearly 100 plus days per year.However, thunderstorms are also frequent along coastal areas which average 80 to 90 days per year.Although Florida thunderstorms are generally less than 15 miles in diameter, they can grow vertically to great heights in excess of 10 miles high into the atmosphere.This stacking effect of concentrated moisture can explain why a Florida thunderstorm directly overhead could produce four or more inches of rain in less than an hour while a location a few miles away may see only a trace.Issued to outline areas where severe thunderstorms may develop and qualifies the degree of risk (i.SLGT, MDT, and HIGH risk areas).Issued to alert the public that conditions are favorable for the development of severe thunderstorms in and close to the watch area.Issued by local NWS offices to warn the public that a severe thunderstorm has been sighted by storm spotters or has been indicated by radar.Room in your Home
Have a NOAA Weather Radio in your home with a tone alert feature.Hail can cause significant bodily injuries such as broken bones and even blindness if wind blown.Zephyrhills, Florida on January 29, 1997.Hailstones the size of softballs can fall at speeds faster than 100 mph.Downbursts have been measured in excess of 100 mph.Downbursts can cause damage similar to that of a strong tornado, and cause loss of life or significant bodily injury from wind blown debris and toppled structures.WARNING means sever weather is occurring or has been detected by radar.Revised, updated, and still unrivaled.The world's premier software reference source.Formation of a thunderstorm.Thunderstorms arise when layers of warm, moist air rise in a large, swift updraft to cooler regions of the atmosphere.Columns of cooled air then sink earthward, striking the ground with strong downdrafts and horizontal winds.At the same time, electrical charges accumulate on cloud particles (water droplets and ice).On occasion, severe thunderstorms are accompanied by swirling vortices of air that become concentrated and powerful enough to form tornadoes.Activate a FREE trial to Britannica Online, your complete (re)search engine for when you need to be right.The temperate and tropical regions of the world, therefore, are the most prone to thunderstorms.Central Europe and Asia average 20 to 60 thunderstorm days per year.It has been estimated that at any one moment there are approximately 1,800 thunderstorms in progress throughout the world.This article covers two major aspects of thunderstorms: their meteorology (i.Thunderstorms are no exception to this pattern.Such an instability can arise whenever relatively warm, light air is overlain by cooler, heavier air.Under such conditions the cooler air tends to sink, displacing the warmer air upward.Thunderstorms develop when deep cells of moist convection become organized and merge, and then produce precipitation and ultimately lightning and thunder.If surface heating is sufficient, the temperatures of the lowest layers of air will rise faster than those of layers aloft, and the air will become unstable.The ability of the ground to heat up quickly is why most thunderstorms form over land rather than oceans (see the map).Mountains, too, can trigger upward atmospheric motion by acting as topographic barriers that force winds to rise.The huge clouds associated with thunderstorms typically start as isolated cumulus clouds (clouds formed by convection, as described above) that develop vertically into domes and towers.If there is enough instability and moisture and the background winds are favourable, the heat released by condensation will further enhance the buoyancy of the rising air mass.Activate a FREE trial to Britannica Online, your complete (re)search engine for when you need to be right."Returned " + google_ads.UNIT, THEN SKIP THAT MANY BEFORE REQUESTING ADS FOR THE SECOND UNIT.More from Britannica on "thunderstorm"...Thunderstorms arise when layers of warm, moist air rise in a large, swift updraft to cooler regions of the atmosphere.Within a single thunderstorm, there are updrafts and downdrafts and a variety of cloud particles and precipitation.Bare, rocky, or paved areas, for example, usually have updrafts above them.The air in contact with the ground ...These conditions include turbulence, icing, and thunderstorms.The energy expended by one thunderstorm is estimated to be greater than that released by an atomic bomb.Tornadoes, hurricanes, and the lightning from thunderstorms kill hundreds of people every year and cause billions of dollars in property damage.Schumann resonance(or Thor's thermometer), worldwide electrical effect discovered by Earle Williams in 1950s; giant electromagnetic echo of every thunderstorm on Earth; resonance rolls around the world 8 times a second; based on idea that amount of lightning in any given area is based on local air temperature; climatologists use it to study subtle signs of global warming.Everyone has seen, and probably been frightened by, these sudden jagged streams of electricity.It is estimated that, at any given moment, about 3,500 thunderstorms are occurring around the world.We have all experienced the darkening skies and sheets of rain
that accompany thunderstorms.In addition to monsters, thunderstorm hazards include
lightning, hail, tornadoes, downbursts, torrential rains and flooding.Weather associated with thunderstorms may have a significant
impact on the environment: flooding may result in severe soil
erosion and lightning strikes may start large fires.In addition, upper level divergence
must exist to support the converging air at the surface.There
are two basic types of thunderstorms airmass thunderstorm and
the severe thunderstorm.The air mass thunderstorm is common in Florida.As with all thunderstorms,
it contains thunder and therefore has lightning.The air mass
thunderstorm lasts approximately one hour and has a very distinctive
life cycle.Cumulus Stage: Rising air, or updraft, cools and forms
the cloud.Lifting mechanism include solar
heating or convergence from a sea breeze.It is not raining during
this stage of the thunderstorm.The precipitation falls
into the updraft.Entrainment into
the downdraft results in some evaporation of the precipitation,
which causes a cooling which makes the air more dense, thus increasing
the downdraft.Hail may also
make it to the surface, but they are not very large.The intensity
of the rain decreases.Prior to the development of a thunderstorm, the air near the surface
is often warm and moist.After the storm passes,
the temperature may begin to rise again.In the air mass thunderstorm the precipitation falls into the
updraft, cutting off the storm's moisture supply and eventually
kills itself.The air mass thunderstorm only lasts about an hour
which is not enough time to produce severe weather.In the Severe
thunderstorm the updrafts and downdrafts are separate from one
another, This allows the storm to last longer and severe weather
may develop.To separate the updraft from the downdraft requires
wind shear.Because
it tilts, when precipitation falls, it does not fall into the
updraft, thus allowing a continuous source of moist warm air to
fuel the storm.Enormous severe storms that
develop and have a tilted updraft are called supercell thunderstorms.Below are some animations of the updraft and downdrafts in a supercell
thunderstorm.Another animation
, from a different perspective, of the updrafts and downdrafts in a severe thunderstorm.Severe weather watches are issued when conditions
are favorable for severe weather.You should seek shelter in the basemant of a
building or in a small interior room such as a closest.If you are in a mobile home, get out and lie down in a
low lying area
Lightning: In the US, lightning
kills on average, nearly 80 people a year.If you are on a lake,
get off.If someone near you gets struck by lightning you may be able to
revive them if you know CPR.In the Middle Ages, people though that you could keep lightning
away by ringing church bells.Why is knowing the condition of the soil important for predicting
flooding?Why are tornado warning sirens so loud and piercing?Why are thunderstorms in the US most common in Florida, yet the
tornadoes are more common in Oklahoma and Kansas?Figure 1: Hail stone measuring 21 centimeters in diameter.The process to initiate vertical lifting can be caused by:
Unequal warming of the surface of the Earth.Orographic lifting due to topographic obstruction of air flow.Figure 2: Multiple lightning strikes from a thunderstorm occurring at night.National Severe Storms Laboratory).For the cumulus cloud to form into a thunderstorm, continued uplift must occur in an unstable atmosphere.Severe weather associated with some these clouds includes hail, strong winds, thunder, lightning, intense rain, and tornadoes.Figure 3: Developing thunderstorm cloud at the cumulus stage.This type of thunderstorm often has severe weather associated with it.The most common type of thunderstorm is the air mass storm.Air mass thunderstorms normally develop in late afternoon hours when surface heating produces the maximum number of convection currents in the atmosphere.The life cycle of these weather events has three distinct stages.The first stage of air mass thunderstorm development is called the cumulus stage (Figure 3).The clouds are the result of condensation and deposition which releases large quantities of latent heat.Figure 4: Mature thunderstorm cloud with typical anvil shaped cloud.The mature thunderstorm begins to decrease in intensity and enters the dissipating stage after about half an hour.Thunderstorms form from the equator to as far north as Alaska.Thunderstorm formation over tropical oceans is less frequent because these surfaces do not warm rapidly.Outside the tropics, thunderstorm formation is more seasonal occurring in those months where heating is most intense.Figure 6: Average number of thunderstorm days per year in the United States.Source: Oklahoma Climatological Survey).Figure 6 describes the annual average number of thunderstorm days across the United States.According to this map, the greatest incidence of thunderstorms occurs in the southeast and in parts of Colorado, Arizona, and New Mexico.This particular spatial distribution suggests that extreme solar heating is not the only requirement for thunderstorm formation.Mountain slopes in these areas that face the sun absorb more direct solar radiation and become relatively warmer creating strong updrafts that form into cumulus clouds.If the differential heating is also supplemented by winds from the east, the cumulus clouds are further enhanced to become thunderstorms.Few thunderstorms occur along the west coast of the United States.This region is dominated by cool maritime polar air masses which suppress convectional uplift over land.Severe Thunderstorms
Most thunderstorms are of the variety described above.Severe thunderstorms are defined as convective storms with frequent lighting, accompanied by local wind gusts of 97 kilometers per hour, or hail that is 2 centimeters in diameter or larger.Severe thunderstorms can also have tornadoes.Figure 7: Model of the major features and circulation patterns associated with a severe thunderstorm.Severe thunderstorms dissipate only when no more warm moist air is encountered.Figure 7 illustrates the features associated with a severe thunderstorm.The green arrows represent the updrafts which are created as warm moist air is forced into the front of the storm.At the back end of the cloud, the updrafts swing around and become downdrafts (blue arrows).Warm moist air that rises over the gust front may form a roll cloud.These clouds are especially prevalent when an inversion exists near the base of the thunderstorm.Some severe thunderstorms develop a strong vertical updraft, commonly known as a mesocyclone.About half of all mesocyclones spawn tornadoes.When a tornado occurs, the mesocyclone lengthens vertically, constricts, and spirals down to the ground surface.The shearing effect of this interaction forces the horizontal wind to flow upward intensifying the updraft.Please see the Encyclopedia of Earth's website for Terms of Use information.Our team of experienced investment professionals
has a proven track record.AdsNum, 0)thunderstorm, violent, local atmospheric disturbance accompanied by lightning lightning, electrical discharge accompanied by thunder , commonly occurring during a thunderstorm .Click the link for more information.The typical thunderstorm caused by convection occurs when the sun's warmth has heated a large body of moist air near the ground.This air rises and is cooled by expansion.The cooling condenses the water vapor present in the air, forming a cumulus cloud cloud, aggregation of minute particles of water or ice suspended in the air.If the process continues, the summit often attains a height of 4 mi (6.As the storm approaches an area, the gentle flow of warm air feeding the cloud gives way to a strong, chilly gust of wind from the opposite direction, blowing from the base of the cloud.Night thunderstorms are caused by the cooling of the upper layers of air by radiation; others are caused by approaching cold air masses that advance as a wedge near the ground, forcing the warmer air in its path to rise.Even a forest fire or a volcanic eruption may create a thunderstorm.Thunderstorms occur most frequently in the equatorial zone (some localities have as many as 200 a year) and seldom in the polar regions.As I did so the shafts of the sun smote through the thunderstorm.Say No by Collins, Wilkie View in contextIn point of fact, a thunderstorm did peal forth, but it was the thunder of applause, or cries, and of uproar which made the very hall tremble.All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. |
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