thunderstorms effects

8/10/2019 Thunderstorms Effects

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Aviation Hazards:Thunderstorms and DeepConvection

TREND

Effects of Thunderstorms on Aircraft


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology

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Contents

Aviation weather hazards associated withconvection / thunderstorms:

1. Turbulence

2. ind shear

!. "cin#

$. Reduced visibilit%&. 'i#htnin#

(. Dama#in# hail

). Tornado / ater *+out

,. -eav% +reci+itation

. ater in#estion1. Altimeter "nterference

-azards at ta0eoff / landin# in fli#ht on the

#round


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3

Turbulence

3ertical dis+lacements velocities and

accelerations4ust front from horizontal outflow from

down draft s+readin# out from storm base/ wind shears


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4

Turbulence Hazards5+ / down draft boundaries within the

cloud

'eadin# ed#e and u++er surface of the#ust front:*tron# vertical and horizontal wind shears

6unnel clouds 7e.#. tornadoes8

5++er e9tent of u+draft within cloud


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5

Vertical Motion Close toConvective Clouds

Aircraft deviations due to convective up and down motion


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6

Cruising Above Cumulonimbus Tops


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7

Turbulence Associated with a

Large Cumulus Cloud


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Turbulence Associated with a

Downdraft


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!

Wind Shear:Shears in Horizontal Winds


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"0

Low-level Wind Shear Hazard

Thunderstorm outflow:

Associated with lowlevel wind shear

a+able of u+settin# the fli#ht of an aircraft

sometime disastrousl%


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""

Downburst Schematic


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Downburst Wind Shears:

Effects on Landing and Taking Off


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"3

Icing in Thunderstorms

;echanism:

Thunderstorm u+drafts su++ort lar#e dro+sof su+ercooled li


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General Icing RegimesAn a#un$an%e of large super%oole$ water $roplets

in a thun$erstorm %lou$ #etween 0& C an$ '20& C


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology "5

Hazardous Effects of Aircraft Icing

Accumulated icin# ma% lower aircraft +erformance: "ncrease stallin# s+eed

Destro% o+timal aerod%namic flow over the aircraft

"ncrease dra#

Decrease lift

ause en#ine failures

ause +ro+eller vibration

"n =et en#ines dama#e com+ressor blades

"nterfere with: ontrol surfaces and landin# #ear

"nstrument readin#s 7e.#. air s+eed altitude and vertical s+eed8

ommunication s%stems

Reduce visibilit%


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Icing Intensity

Trace"ce is +erce+tible > not hazardous unless

e9+osure is for an e9tended +eriod

'i#htAccumulation rate ma% cause +roblems if

fli#ht is +rolon#ed

;oderate*hort +eriods of e9+osure become hazardous

*evere*hort term e9+osures are hazardous and an

immediate diversion is necessar%


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Reduced Visibility;echanism:

-orizontal visibilit%Due to +reci+itation *howers of rain snow and hail

3ertical visibilit%Due to obscurin# cloud

umulonimbus *tratus etc.


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology "

Lightning

A hi#hcurrent electrical dischar#e causedb% a thunderstorm ?loudtocloud

ithincloud 7@ & of all stri0es8loudto#round > +rime hazards to +eo+le7ris0 of electrocution8 or +ro+ert% on the#round

4enerall% the hi#her the fre


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology "!

Lightning


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology 20

Lightning: Aircraft Damage

Direct dama#e

Buncturin# the fusela#e

Curnin# meltin# or distortin# aircraft +arts "ndirect dama#e

Tem+orar% or +ermanent dama#e to avionics

6ire in the fuel s%stem

Tem+orar% blindin# of the +ilot

3isual or instruments


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology 2"

The Effects of Lightning on

Aircraft

6li#ht *afet% Australia ;a#azine article:

Colt from the Clue htt+://www.casa.#ov.au/fsa/2&/au#/$,&.+df
http://www.casa.gov.au/fsa/2005/aug/48-50.pdfhttp://www.casa.gov.au/fsa/2005/aug/48-50.pdf


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Damaging Hail

-ail can inflict severe dama#e to anaircraft in fli#ht or on the #round

-ail is mostl% a midlatitude +henomenon

An intense thunderstorm allows:*torm u+drafts are stron#'ar#e hail is sus+ended and circulated u+ and

down within the could until it falls from the

storm cloud-ail stones accumulate mass b% swee+in#

throu#h su+ercooled water dro+lets and ice+articles


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Funnel Clouds:

Tornado / Water Spout

Tornadoes / water s+outs are usuall%

identified b% a funnel cloudTornadic winds are e9tremel% destructive > themost violent weather +henomenonan cause structural dama#e to an aircraft

Tornado formation de+ends on the wind shear

environment of the severe storm


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Heavy Precipitation

Thunderstorms are ca+able of e9tremerainfall intensities

-eav% +reci+itation can:Reduce visibilit% in fli#ht and on the #round

*t. ElmoFs 6ireBreci+itation es+eciall% in vicinit% of a thunderstorm

can build u+ static electric on the aircraft "nterferes with radio transmission

Nois% disturbance at low radio fre reduce sto++in# abilit% u+onlandin# and decrease steerin# control on the#round

6loodin# of airfield bo##% environs


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Water Ingestion "f thunderstorm u+draft sus+ends

sufficient water dro+lets ?

Get en#ine ma% in#est more water than desi#ns+ecifications

an lead to en#ine flameout

There is no 0nown successful o+erational recover%

+rocedure


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Altimeter Interference

Air +ressure chan#es often res+ond to athunderstormHs downdraft ?5suall% the +ressure chan#es are ver% ra+id

As the storm a++roaches often the +ressurefalls steadil%

Air +ressure then rises ra+idl%ith the onset of #ust front and arrival of the cold

down draft 7with heav% +reci+itation8

Air +ressure falls bac0 to ambient +ressure

when the storm moves awa%Total c%cle time I 1 to 1& minutes onl%

hence the altimeter could be of the order of1 feet in error


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*tatisticall% the most hazardous +hase offli#ht is ta0eoff and /or landin# Turbulence

ind shear

Reduced 3isibilit%: 3ertical visibilit% due to loud 7b *t etc8

-orizontal visibilit% due to Breci+itation 7*-RA *-4R

*-*N8

'i#htnin#

Dama#in# hail Tornado / ater *+out

-eav% +reci+itation

ater in#estion

Take-off / LandingThunderstorm Hazards


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Downdrafts Interfering withLanding and Taking Off

Landing, left to right

Taking off, right to left


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology 2!

In-flight Thunderstorm Hazards

Turbulence

ind shear

"cin# Reduced 3isibilit%:

3ertical visibilit% due to loud 7b *t etc8 -orizontal visibilit% due to Breci+itation

7*-RA *-4R *-*N8

'i#htnin#

Dama#in# hail Tornado / ater *+out

ater in#estion


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On-the-ground

Thunderstorm Hazards

Turbulence / 4usts / *tron# inds

'i#htnin# Dama#in# hail

Tornado / ater *+out

-eav% +reci+itation


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Copyright Commonwealth of Australia 2006, Bureau of Meteorology 3"

Strong Gusts Blew these Aircraftinto Each Other on the Ground


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SummaryThunderstorms are e9tremel% hazardous

to fli#ht

Bilots should avoid thunderstormsbecause of the number and severit% ofassociated hazards

6orecastin# thunderstorm activit% in a

timel% and accurate wa% has #reat utilit% tothe aviation "ndustr%


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Copyright Commonwealth of Australia 2006,Bureau of Meteorology 33

6orward to

*atellite and radar observations of thunderstorms
http://www.caem.wmo.int/_pdf/thunderstorms/thunderstorms_03_imagery.pdfhttp://www.caem.wmo.int/_pdf/thunderstorms/thunderstorms_03_imagery.pdf

thunderstorms effects

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