SCIENCE NEWSSCIENCE NEWS

Thunderstorms

What are thunderstorms?What are thunderstorms?

A storm which containsA storm which contains

lightning and thunder lightning and thunder

Why Study Thunderstorms ?Why Study Thunderstorms ?

FatalitiesFatalities InjuriesInjuries

Property Damage Property Damage Crop DamageCrop Damage

Weather related deaths in the Weather related deaths in the u.s.u.s.

Weather damage costWeather damage cost in the U.S. in the U.S.

According to NOAA’s National According to NOAA’s National Weather ServiceWeather Service

The US has sustained 90 The US has sustained 90 weather related disasters over weather related disasters over the 29 years the 29 years

Total cost of all 90 events?Total cost of all 90 events?

$700 billion$700 billion

ILLINOIS ILLINOIS According to NOAA, 2008 Summary According to NOAA, 2008 Summary

of Hazardous Weather Fatalities, of Hazardous Weather Fatalities, Injuries, and Damage Costs by Injuries, and Damage Costs by

StateState Fatalities 35 Fatalities 35 Injuries 48 Injuries 48 Property Damage $ 227.14 millionProperty Damage $ 227.14 million Crop Damage $ 41.04 millionCrop Damage $ 41.04 million Total - $ 268.18 millionTotal - $ 268.18 million

Average number of days perAverage number of days peryear with thunderstormsyear with thunderstorms

FACTSFACTS

FEATURESFEATURES Cumulonimbus Cumulonimbus

cloudsclouds Heavy rainfallHeavy rainfall LightningLightning Occasional hailOccasional hail

OCCURANCESOCCURANCES 2000 in progress 2000 in progress

at any one timeat any one time 100,000 per year 100,000 per year

in the United in the United StatesStates

Most frequent in Most frequent in Florida and Florida and eastern Gulf eastern Gulf Coast regionCoast region

All thunderstorms needAll thunderstorms needMoisture Moisture -- source typically over source typically over water, cloud formation & rainwater, cloud formation & rain

LiftingLifting- - mechanism for condensing mechanism for condensing moisture to release its latent heatmoisture to release its latent heat

Unstable air-Unstable air- rising air warmer rising air warmer than the surrounding air, produce than the surrounding air, produce

upward growing clouds and upward growing clouds and vertical updrafts keep precipitation vertical updrafts keep precipitation

suspendedsuspended

2 Types of Thunderstorms2 Types of Thunderstorms

Classified by lifting mechanismClassified by lifting mechanism

1. Air mass1. Air mass - unequal heating of - unequal heating of surfacesurface

MountainMountain : Orographic lifting : Orographic lifting

Sea breezeSea breeze : difference between : difference between land/water storage & release of land/water storage & release of thermal energy thermal energy

2. Frontal2. Frontal – advancing cold fronts and – advancing cold fronts and

more rarely warm frontmore rarely warm front

Stages of developmentStages of development

3 distinct stages make up a t-3 distinct stages make up a t-stormstorm

Cumulus stageCumulus stage

Warm, humid air rises vertically and Warm, humid air rises vertically and condenses into a cumulus cloud condenses into a cumulus cloud

Large amounts of latent heat are Large amounts of latent heat are release inside the cloudrelease inside the cloud

As the cloud grows, particles As the cloud grows, particles eventually get heavy enough toeventually get heavy enough to

fall also sides of the cloud evaporates fall also sides of the cloud evaporates forming a downdraftforming a downdraft

No precipitation during this stageNo precipitation during this stage

Cumulus StageCumulus Stage

Mature stageMature stage

The appearance of a downdraft The appearance of a downdraft Updraft/downdraft is called a Updraft/downdraft is called a

““cellcell”” An “anvil” top appears as the An “anvil” top appears as the

updrafts hit the tropopauseupdrafts hit the tropopause Heavy rain possible in this stageHeavy rain possible in this stage Strong/gusty surface windsStrong/gusty surface winds

Mature StageMature Stage

DissipationDissipation

Downdrafts basically choke out Downdrafts basically choke out the updraftsthe updrafts

Cuts off the warm, moist air Cuts off the warm, moist air which is the energy supply for which is the energy supply for the stormthe storm

Light rain onlyLight rain only

Dissipating StageDissipating Stage

Multi cell thunderstormsMulti cell thunderstorms

If new thunderstorms forms If new thunderstorms forms due to downdrafts from the air due to downdrafts from the air mass, they are called “mass, they are called “multi multi cellcell” thunderstorms” thunderstorms

Most severe storms & ordinary Most severe storms & ordinary storms are multi cell storms storms are multi cell storms

Multi cell ThunderstormMulti cell Thunderstorm

Thunderstorm hazardsThunderstorm hazards Hail Hail

Collision of super Collision of super cool water drops cool water drops forms layersforms layers

Cause extensive & Cause extensive & quick damage quick damage

Largest Aurora, Largest Aurora, Nebraska 6/03 Nebraska 6/03

7 in diameter & 7 in diameter & 18.75 in 18.75 in circumference circumference almost a soccer ballalmost a soccer ball

Lightning & ThunderLightning & ThunderCharge differences Charge differences between the between the thunderstorm and thunderstorm and ground can cause ground can cause lightning strokes lightning strokes of 30,000°C, and of 30,000°C, and this rapid heating this rapid heating of air will creates of air will creates an explosive shock an explosive shock wave called wave called thunder, which thunder, which requires requires approximately 3 approximately 3 seconds to travel 1 seconds to travel 1 kilometerkilometer

Lightning Stroke DevelopmentLightning Stroke Development

Charge layers in the cloud Charge layers in the cloud are formed by the transfer are formed by the transfer of positive ions from of positive ions from warmer hailstones to warmer hailstones to colder ice crystals.colder ice crystals.

When the negative charge When the negative charge near the bottom of the near the bottom of the cloud is large enough to cloud is large enough to overcome the air's overcome the air's resistance, a stepped resistance, a stepped leader forms.leader forms.

A region of positive ions A region of positive ions move from the ground move from the ground toward this charge, which toward this charge, which then forms a return stroke then forms a return stroke into the cloud.into the cloud.

Lighting Lighting

• Several names, such as Several names, such as forked, bead, ball, and sheet forked, bead, ball, and sheet lightning describe forms of the lightning describe forms of the flashflash

• Distant, unseen lightning is Distant, unseen lightning is often called heat lightningoften called heat lightning

2007 Lightning Fatalities2007 Lightning Fatalities 45 lightning fatalities45 lightning fatalities Above the 10-year average of Above the 10-year average of

44 fatalities.44 fatalities. For the 9th consecutive year, For the 9th consecutive year,

Florida was hardest hit with 11 Florida was hardest hit with 11 fatalitiesfatalities

Illinois 1 fatalityIllinois 1 fatality

ANY QUESTIONS?

HOMEWORKHOMEWORK QUIZ? QUIZ?

Read Ch 13 p 344- 349Read Ch 13 p 344- 349

Ch 13 Study Guide Due Tues 4/28 Ch 13 Study Guide Due Tues 4/28

Ch 12 test corrections due TR Ch 12 test corrections due TR 4/304/30

Good ReferencesGood Referenceshttp://www.eoearth.org/article/Thunderstormhttp://www.eoearth.org/article/Thunderstorm

USE THIS FOR SEVERVE TSTROMSUSE THIS FOR SEVERVE TSTROMS

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