TORNADOES- QUESTTONS
ARTICLE1
1. Definethe term tornodo.
2. Describethethree (3) keyconditions
thot ore reguiredfor thunderstorms
to occur.
3. On average,howlongdo tornadoesusuollylast?
ARTICLE2
Tornodoesin Canado
Use the groph to onswerthe followinqguestions.
Canadiantornado distribution
( 5 t )b y p r o v i n c e1 9 5 0 - 1 9 9 7
Que
M a r t i me
Author Chridiire Eisen
A. Which provincehos the most tornodoes2
B. Whichprovincehosthe leostnumberof tornodoes?
C.Whichtwo pnovinces
haveneorlythe somenumberof tornodoes?
D. List the provinces
from leostto greatestnumbersof tornodoes.
Yeorly Tornodoesin Conodo
Use the groph to onswerthe guestionsbelow.
C anadian
Tornado
as a perceniage
OccuEnce
by month
Dat
i{.,,.
Author
A . fn whaf monthdoesConodareceive
mostof it tonnodoes?
B. Whichmonthsorethe numberof tornodoes
neorlythe some?
c.Whichmonthreceivesno tornodoes?
D .Whot hoppensto the numberof tornadoesreceivedfrom Morch to June?
to fhe numberof tornodoesreceivedfrom July to November?
E. Whot hoppens
F. Whot seosonreceivesthe most tornodoesZ
6. Whot seosonreceivesthe leost tornodoes?
ARTICLE 3
1.
2.
3.
4.
On averagehowmanytornodoesdoesConodaexperience
withinayear?
TornodoAlley?
Where is Conodo's
What time of the doydo the mojorityof tornodoesusuollyoccur?
fn whot provinces
hovethe worst tornodoesin Conodo
occurred?
ARTICLE4
1. fn whot regionsof the worlddo tornadoesoccur?
2. Howare the mojorityof tornodoesin the UnitedStotesformed?
3. Whereis the UnitedStotesTornodoAllev?
- Ch.istina
lr..
Eieen
ARTICLE#1
Tornodoesore Eorth's most violent sforms
Tornodoesarethe mostviolentstormson Eorth.Windsspiralinginto themusuollyexceed100mph
ondconreoch speedsof 300 mph.In the USA,on averageof 1,000tornodoesspinup beneoth
eochyeor,ondthesetypicollykill obout60 people.
thunderstorms
spring
Tornodoes
ondthe threot of tornadoesore o key port of the USA'sspringweatherbecouse
But tornodoesconoccurdnytimeof theyear, duringthe doy
bringsfovorobletornodoconditions.
ondot night.
The NotionolWeotherServicedefineso tornodoos "o violentlyrotatingcolumnof oir in contqct
is the first
fn otherwords,o thunderstorm
with the groundondpendontfrom o thunderstorm."
ore right,the thunderstorm
mightspin
stepin the creotionof o fornodo.Then,if other conditions
out oneor moretornodoes.
to form ore:
The three key conditionsreguiredfor thundarstorms
. Moisturein the lowerto midlevelsof the otmosphere.
. Unstoble
oir. Thot is,oir thot will continue
risingonceit beginsrisingfrom nearthe ground.
. A liftingforce.Something
isneededto cousethe oir to beginrising.Themostcommon
lifting
lighterondbeginsrising.
f orceis heotingof oir neortheground.Astheoir wormsit becomes
Advoncing
mossesof cooloir, whichf orcewarmoir upword,olsotrigger thunderstorms.
into
arepresenl,humidoir willrisehighintothe skyondcoolondcondense
Whenoll the conditions
is
This
into
o
on
oir
thunderstorm
colled
updnoft.
thunderstorms.
rising
toweringclouds,
forming
updroft.
Tornodoes
form in withino thunderstorm's
The strongesttornodoesare often nearthe edgeof the updroft,not far from whereoir is
in o downdroftcousedby the thunderstorms
with follingroin or hoil.This is whyo burst
descending
onnounces
o tornodo'sorrivol.
of heavyroin on hoilsometimes
Tornodoes
ossocioted
ore commonly
with the notion'sheortlond- in o lO-stoteareastretchingfrom
fowa,f llinois,fndiono,MissouriondArkonsos.known
Texosto Nebraskothot olsoincludes
Colorodo,
os TornodoAlley.
hoveoccurredin oll 50 U.5.stotesondore, in
But,they are not limitedto this region.Tornodoes
in Floridothonthey ore in Oklohomo.
fact, morecommon
weok- f or tornadoes- with windsoround100mph.
Floridotornodoesare generally
Tornodoes
on the other hond,ore someof the mostviolenton record.A
thot hovehit Oklohomo,
Cityondits southernsuburbsint999 hodwindsof neorly320 just
tornodothot struckOklohomo
obovethe ground.
Tornodoes
ore ronkedby the domage
they do usingthe six-tieredFujitoScole.F0 andFl tornodoes
to moderotedamage
with windsfrom4O-LL2
on the scoleoreconsidered
"weok"ondcouseminimol
strong,pockingwindsof tL3-2O6mphthot concouse
mph.F2 ond F3 tornodoesore considered
mojorto severedomoge.
Violenttornodoesore thoseclossified F4 ondF5 with windsexceeding206
mph.Domog
e is extremeto cotostrophic.
Violenttornodoeshavebeen
Most weoktornodoeslast 10minutesor less,trovelingshort distonces.
knownto lost for hoursanda f ew hovetroveledmorethon 100miles.
ARTICLE#2
Storms; Tornodoes
D o y o u? e m e m b tehre s t o r y " T h e W i z o r d oOfz "o n d h o w D o r o t h y , h e r h o u s e o n d h e r d o g T o t o w e r e
corriedto the londof "Oz" by o tornodo.WhileDorothy'strip moyhavebeeno dreom.tornodoes
ore not. fn fact, tornodoesore nature'smostpowerfulstormsondore fearedmorethonanyother.
Whot is o Tornodo?
Scientistsdefineo tornodoos "o violentlyrototingcolumnof oir thot extendsfrom o
destruction.
thunderstormto the ground".The mostviolenttornodoesore copobleof tremendous
400
per
Trovelling
per hourwith windspeedsupto
kilometres hour,they concut
ot 100kilometres
longin minutes.
fn the UnitedStotes.
o pothof 1.5kilometres
wideond80 or morekilometres
wheremosttornadoesoccur,on
overageof 800 tornodoesarereportedyearly.Theycousefewer thano hundreddeoths,but
of injuriesondmonymillionsof dollorsin domoge.
thousonds
How do tornodoesform?
The funnel
Tornadoes
olthoughnot oll thunderstorms
cousetornodoes.
form withinthunderstorms,
in opposite
directions
setso
of o tornodofirsf formsoloft whereoir moving
cloudchorocteristic
is themtilted downward
betweenthem.Thiscolumn
towordsthe groundby
of oir spinning
cofumn
mossiveoir currentsthot moveupwordthroughthe thunderstormcloud.Youcondemonstrotethis
o
eff ect by plocing
pencilbetweenthe polmsondthemmovingyour hondsin oppositedirectionsondthen by tilting
yourhondtowordsthe tobleso the pencilstondsup-right.Therollingpencilwouldthen be likeo
tornodo.
Are there different kinds of tornodoes?
Thesearethe ones
The mostcommon
tornodoesform duringthe earlystogesof o thunderstorms.
we seemostof ten on televisionwhentornodoesare beingstudiedby storm-chosersor reportedon
Thesetornodoesstort off procticollyinvisibleondbecomedork onlywhenthey
newsprogroms.
sfart pickingup dust onddebris.Anothertypeof tornodoforms overwormwoter.Theseare called
moveinlondondbecomefull blowndestructivetornodoes.
woterspouts.Woterspoutsoccosionolly
When ore tornadoesmost likely to occur?
Tornqdoes
conhappenonytime of Ihe yeorondonytime of doy.BetweenMorchandMoy,the peok
are reportedmonthly.Mosf tornodoesoccur
seosonfor tornodoesin North Americo,hundreds
they hoppenin the middleof the night cotching
\etween3 p.m.ond9 p.m.of the doy.Sometimes
peopleoff guordondunprepored
for the horror thesestormsconcouse.
monyunsuspecting
tornodoes.
Most tornodoestouchdownin the United
Not oll areasof the world experience
oll the woyto the proirie
Stotesfrom the coostof the Gulfof Mexiconorththroughthe mid-west
provinces
of Conodo.
How ConYou Prepore for o Tornodo?
weotherfor signsof o tornodoondthen if o
Preporing
for o tornodomeonsfirst wotching'the
shelterin o plocethe tornadoconnotdestroy.Preparedpeople
tornodoworningis issuedseeking
ondif onethot looksthreoteningis spottedheodto on underground
wotchingfor thunderstorms
food, wafer, f loshlightsondo bottery operated
bunkerstockedwith emergencysupplies,especially
rodioto listenfor further wornings.
FoscinotingFocts About Tornodoes
. Tornodoes
directionondevendoublebockontheir trock.
consuddenlychange
. The soundmodeby o tornodois often compared
to the rumbleof anearbytroin or the soundof
cor.
windowin o speeding
o woterfollor oir rushingby on opened
. Most tornadoeslost less10minutes.Somehovebeenrecordingas lostingon hour.
. Tornodoes
fn Austrolio,
the spinin the opposite
in North Americospincounter-clockwise.
direction;clockwise.
. The sizeandshapeof o tornodohosnothingto do with its strength.
. ThedeodliesttornodoeverrecordedstruckfllinoisonMorch25,t925.It killed689people.
. People
of metresbyo tornodohovelivedto tell of their "hoirroising
carriedhundreds
experience".
. Concdois secondto the UnitedStotesin the numberof tornodoesit gets.About4OOare
reported in Conodoeachyeor.
ARTICLE#3
Tornodoesin Conodo
80 tornodoes,
two deoths,20 injuriesondtens
Canada
experiences
cousing
Duringan overageyear,
of millions
of dollorsin propertydomoge.
Conodo's
"tornodoolleys"ore southernOntorio,Alberto,southeostern
Quebec,ondo bond
ondMonitobothroughto ThunderBoy.The interiorof
sfretchingfrom southernSaskotchewon
ore olsotornodozones.
ondwesternNewBrunswick
BritishColumbio
in JuneandeorlyJuly.Although
is usuolly
Tornodoseoson
Morchto August,with the peokseoson
of
year,they
are?are
during
the
winter.More thon 80 per cenlof
occur
of
ony
con
time
tornodoes
strike betweennoonandmidnight.
oll tornodoes
do little morethanbreokoff ontennoe,
uproottrees or
Fortunotely,mosttornodoesin Conado
domogeweokstructures.With windspeedsof lessthon 160kph,ondo poth 100m wideby 2 km
long,thesesmolltornodoescouselessthon threeper centof deoths.Strongtornodoeswith winds
of morethon 300 kphcousethe mostdestructionondinjury.
Conodo
will issueasevere Weother Wotch.ff o storm
Tf aseverestorm is brewing,Environment
your
oreo,Environment
Conodo
will then issueo SevereWeother
is imminentor confirmedin
Worning.Wheno TornodoWorningis issued,listenfor newsupdotasondbepreparedto toke cover
of o moment's
notice.
Dote
:
Tfte:Worst tanadiari
"oo*Oolr*.1;,
InJured Dcnogc
Locstion
June30,1912 Regino
July31,1987
June17,1946
Aug.16,1888
April3. 1974
Edmonton
Windsor,Onf.,to Tecum*eh;
Ont.
LancasterTownto Voley{eld Que
Windsor,
Ont.
28
100s $4 million
77
300
$25Omillion
t7
1O0s
$1.5million
9-11
9
Source: Environment Canada
L4
n.o.
30
$500,000
ARTICLE#4
TornodoAlley in the Midwest
April throughJuneis tornodoseosonocrossmostof the UnitedStotes.
W h i l e 9 0 % o ft o r n o d o e s s t r i k e i n t h e U n i t e d S f o t e s d u e t o s t ocrrme sa t e db y d r y c o o lp o l o r o i r
whichmeetswormmoistoir from the Gulfof Mexico,tornodoesoctuollystrike oround
from Conodo
the world.About800-1200tornodoesoccurin the U.5. eachyearolthoughmostoccurin
areos.A largeproportionof UnitedStotestornodoesstrike in on oreoknownas
uninhobited
TornodoAlley,whichstretchesfrom northwestTexos,ocrossOklohomo
and Konsos.
Tornodoes
form o circulorcolumnof lowpressure(upto obout100millibarslowerthon the
surrounding
oir) whichhosveryfost windcirclingoroundit ot speedsof ?OOto 500 milesper hour.
These450-1800foot widecolumns
condrivestrow into woodondwoodinto metolos they create
their pothof destruction.
Tornodoes,
olsoknownss twisters,usuollymoveof obout15to 30 milesper hourtowordsthe
ond
lost from o few minutesto os longos eighthours.Tornodoes
kill obout90 peopleeoch
northeost
year in the UnitedStotesondore the mostdestructive
of onylocolotmospheric
The
disturbonce.
wind,not the lowpressure,ossocioted
with o tornodois whotcousesthe domoge,
whichconmodea
city looklike it wosbombed(expertsodviseogoinstopening
windows
wheno tornodoopprooches).
Tornodoes
occurin oll fifty stotes.TexosondOklohomo
hovetornadoesmostfreguentlybut
Mossochusetts
hasthe highesttornododeothrote,dueto thestote's muchhigherpopulotion
densitythan CentrolPloinsstotesondo 1953tornodothot killed94 people.
Other regionsof the worldwith freguenttornodoesincludeConodo,
southernBrozil,South Africa,
easternondwesternAustrolio,Bonglodesh,
The UnitedKingdom
Europe,Jopan,ondNewZealand.
hodweokbut o very highincidence
of tornodoesper acre,morethonthe UnifedStotesos o whole.
Thedorkgroycolorcommonly
ossocioted
is dueto the soilondother objects(os
with tornodoes
largeasroilroodcors)pickedupondblownby the winds.
fn the UnitedStotes,the NotionolWeatherService(NWS)issuestornodowotchesondwornings.
A
ore conduciveforo tornodoto occurwhileo worningmeonsthot o
wotchmeonsthot the conditions
tornodohosoccurredor is oboutto occur.