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PPL > PPL MET > Flashcards

PPL MET Flashcards

1
Q

Atmosphere Divisions
Nitrogen
Oxygen Other gases

A

78%
20%
2%

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2
Q

Troposphere

A 
Temp decreases with height 
2*/1000 
15*C --> -56.5*C top
Temperature based on ISA 
All weather occurs 
Lapse rate (temperature decrease) stops or stay constant
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3
Q

Tropopause

A
  • isothermal lapse rate
  • cloud
  • high cloud tops
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4
Q

Stratophere

A
  • temperature increase with height due to ozone layer
  • temperature inversions
  • -56.5 at stratospause
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5
Q

Stratopause

A
  • similar to tropopause
  • temp lapse rate pauses + stay constant
  • negative lapse rate
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6
Q 
Conduction 
Convection 
Radiation 
Advection 
Latent heat
A
  • 2 touching particles will transfer heat between each other
  • heated particles will rise allowing cooler particle to sink
  • transfer of electromagnetic waves (solar + terrestrial )
  • horizontal movement of air masses
  • absorption + release of heat energy through evaporation, freezing + condensing
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7
Q

DALR

SALR

A

3/1000

1.5/1000

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8
Q

Saturation

A

100% filled with water = reached saturation
a particle is saturated - cloud
100% humidity
water vapour condenses into visible moisture (latent released to environment)

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9
Q

Relative Humidity

A
  • amount of water in a particle compared to amount possible
    Humidity = vapour present / vapor possible x 100
  • how close to saturation or 100% a particle is
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10
Q

Dew Point Temperature
to reach 100% humidity

The greater the water present =

A
  1. constant amount of water vapour present
    - particle cooled until it reaches the dew point tempreature
    - as it rises it cools until it reaches DPT + cloud forms
  2. kept a constant temperature
    water vapour is added until it reaches 100% humidity
    = the higher/warmer the dew point
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11
Q

Stability

A

parcel of air is the same temperature as it surrounding environment + will be minimal vertical movement
- cloud form in a stable atmosphere there must be lifting mech

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12
Q

Unstable

A
  • when a parcel of air is warmer than its surrounding environment + continues to rise
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13
Q

Cumuliform

A
  • produced in an unstable atmosphere
  • by rising convective air
  • cumliform clouds are heaped or towering in appearance
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14
Q

Stratiform

A
  • produced by stable conditions

- flat and layered in appearance

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15
Q

Low level ___ft
Mid Lvel ___ft
High level___ft

A

7-8000ft
7-8000 to 20000ft
20,000ft and higher

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16
Q

Cirrus

A
  • high level cloud
  • white + fibrous
  • composed mainly of ice crystal
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17
Q

Cirrocumulus

A
  • high level cloud
  • thin + sheet-like, covering the whole sky (hale effect)
  • ice crystal
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18
Q

Altocumulus

A
  • mid level cloud
  • white or grey layer in arranged dump
  • water droplet + super cooled water droplet
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19
Q

Altostratus

A
  • mid level cloud
  • grey/bluish layer, often covering all of the sky (halo effect)
  • water droplet, supercooled water droplet + ice crystal
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20
Q

Nimbostratus

A
  • low or mid level cloud
  • grey, dark grey
  • continous snow or rain
  • water droplet - heavy continous rain
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21
Q

Stratocumulus

A
  • low level cloud
  • grey / whitish layer with darker elements
  • water droplet
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22
Q

Stratus

A
  • low level cloud
  • grey layered cloud with a uniform base
  • water droplet
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23
Q

Cumulus

A
  • low level cloud
  • detached with sharp outlines, like rising mounds
  • water droplets, larger with supercooled water droplets
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24
Q

Cumulonimbus

A
  • low level cloud
  • heavy + dense with great vertical growth(thunderstorm)
  • water droplet + supercooled water droplet
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25
Q

Low pressure System

A
  • clockwise in the southern hemisphere (AC in Northern)
  • airflows converges at the surface + rises
  • most unstable + brings adverse weather
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26
Q

Coriolois Force can be increased with

A

more mass+ density mass

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27
Q

High pressure

A
  • anti-clockwise in Southern(C nothern)
  • air subsides down towards the surface then spreads out
  • stable conditions
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28
Q

Coriolis force

A
  • earth’s rotation
  • southern hemisphere = as particle moves north its path over the earths is deflected left
  • earth rotating west to east
  • closer to equator = coriolis force decreases
  • at equator = zero
  • closer to ground the coriolis decreas due to surface friction
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29
Q

Wind gradient

A
  • main cause of surface wind is local pressure changes
  • circulat patterns with high and low pressure are due to pressure gradient
  • closer the isobars are the the greater the pressure gradient and wind speed
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30
Q

Buys ballot law

A
  • his back to the wind in the souther hemisphere

- lowest pressure will always be on his right hand

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31
Q

Backing

A
  • anticlockwise direction (observer turns to his left I continue facing the wind)
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32
Q

Veering

A
  • clockwise direction (observer turns to his right to continue facing it)
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33
Q

Surface Friction

A
  • 3000ft
  • below this layer the wind speed + direction changes due to the friction caused by the earth’s surface
  • over land: wind veer by 30*C and speed decrease by 2/3
  • over seas: wind veer by 10*C and speed decrease by 1/3
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34
Q

gradient flow

weaker/stronger than coriolis

A 
weaker = left flow (high pressure) 
stonger = right flow (low pressure)
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35
Q

geostrophic

A

isobars are straight
balance
constant speed along straight isobars

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36
Q

Gust

A

rapid increase then fill in wind speed

37
Q

Squalls

A

wind changes in at least 16kts to reach 22kts for at least 1min

38
Q

Land breeze

A
  • coastal regions
  • night the land cools much quicker than the sea
  • produces a pressure gradient due to the temperature differential
  • greater the temperature differential the stronger the wing
  • lighter than sea breeze
39
Q

Sea breezes

A
  • coastal region
  • differential heating between land and sea
  • summer or hot days
  • sea is poor conductor of heat
  • afternoon the land becomes warmer compared to the ocean
  • greater the temeprature difference the stronger the winds
  • 3pm
40
Q

katabatic winds

A
  • forming in the evening, flowing down slopes or hills
  • land loosing heat at night due to terrestial radiation
  • strongest on cloudless night
  • cold, dense air slides down mountains
  • light
41
Q

Anabatic Winds

A
  • during the day
  • ground is heated up
  • hot air rises
  • weaker than katabatic wind
42
Q

Fohn Wind

A
  • humid air is forced up over a mountain
  • as it rises cools adiabatically to reach its dew point
  • cloud is formed
  • latent heat is released
  • warm dry air flows down the lee side
  • cloud base will be higher on windward side
43
Q

How are fronts formed

A
  • air masses move and encounter air of differing temp

- air have different densities very little mixing between air masses

44
Q

Cold Fronts

A
  • heavier air + dense + slides underneath warm air
  • cold air advances its force warm air to rise forming a cold front
  • air that is forced to rise is unstable + produces unstable conditions
45
Q

Frontal Approach of cold front

A
  • wind speeds increase to 15-50kts
  • wind north-north westernly
  • temperature increase + pressure decreases
  • cumulus. Cumulusnimbus, rain
46
Q

Cold front Passage

A
  • wind back to south/west
  • temp falls + pressure rises
  • humidity rises
  • thunderstorms or squalls, low clouds
47
Q

Warm Fronts

A
  • cold air retreats and warm air occupies previous position
  • warm air is still forced to rise over heavier cold air = warm front
  • stable = cirrus/cirrostratus/all weather
  • cloud then will thicken and lower
  • nimbostratus = heavy continous rain
  • warm air now overing over cold ground = very stable
48
Q

Warm front Approach

A
  • wind speed 20kts
  • cloud developing well ahead of front thickening
  • wind from the north-east
  • pressure falls
  • rain beginning well ahead of front
49
Q

Warm Front Passage

A
  • wind backs to north-west
  • rain eases then stops
  • cloud clears to south-east
  • Temp starts to rise
  • Humidity increases + pressure steadies
50
Q

occluded fronts

A
  • cloud fronts travel faster than warm fronts
  • cold front can overtake a warm front
  • warm front travels clockwise around a low pressure cold front + cold front can catch up to the warm front
  • features both weather from cold and warm
51
Q

Stable
Unstable
Conditionally Unstable

A

DALR>SALR or ELR = stable
ELR > DALR or SALR = Un-stable
DALR> ELR or SALR = Conditionally un-stable

52
Q

Fog
Formation of fog
Clearing of Fog

A
  • cloud on the ground
  • vis reduced below 1000m
    1. clear skies at night
    2. light winds
    3. humid air
  • increase wind strength
  • increase solar heating
  • lift to low stratus cloud
  • thicken due to mixing then will start to lift or dissipate
53
Q

Mist

A
  • vis is 1000m or greater
54
Q

Radiation Fog

A
  • forms over land during evening or early morning
  • at night earth loses heat due to terrestrial radiation
  • air above ground is cooled by conduction
  • if air is moist its cools to its dewpoint + fog forms
55
Q

Advection Fog

A
  • Horizontal passage of warm moist air over a cold surface
  • moist air is cooled down to dewpoint
  • found over the sea or coastal regions
  • during night or day
56
Q

Inversions

A
  • temperature decreases with height in the trospophere
  • warmer layers of air can sit above cooler layers
  • temperature inversions - temperature is increasing with height
  • convections limited to below the inversion layer (trapped by warm air above)
  • inversions stable conditions
57
Q

Inversion conditions

A
  • below inversion layer - port vis + bumpy conditions

- above inversion layers - good vis + smooth flying conditions

58
Q

Radiation Inversion

A
  • common type of inversions
  • forms on the earths surface night
  • at night - ground cools due to terrestial radiation
  • air is poor conductor = limited to a fairly this layer + air above is virutally unaffected
59
Q

Cold Air

A
  • moves into a region occupied by warm air
  • cold air is denser and slide sin underneath warm air
  • warm air now sits above cold - inversions
  • local surface heating can cause cold air to heat and rise
  • if above warmer parcel is warmer than rising air, convection ceases
  • visibility is reduced and bumpy conditions below the inversion layer
60
Q

Subsidence layer

A
  • inversion formed in a high pressure system
  • air is a high pressure system subside (it sink its spread out, diverges)
  • as it fails the sinking air warms adibatically above the diverging air
  • subsidence inversions form over summer in the subtropical ridge
61
Q

Low level jet stream

A
  • high pressure system to the west
  • mountain range
  • inversion layer
  • morning (6-9am)
  • high wind speeds found a low level in early hours of morning (up to 50kts)
  • form when surface inversions are the strongest
  • inversions shields the winds from the frictional forces of the terrain
62
Q

Dust devil

A
  • unstable conditions
  • small scale swirling cloud of dust
  • reduced vis
  • cloud cause windscreen abrasion
63
Q

Turbulence

A
  • sun heating up the ground
  • ground heats up the air and the air rises
  • convective turbulence can be found underneath and within the cloud
  • cloud may form (depending on moisture)
  • convective turbulence will be strongest on hot summer days
64
Q

Mechanical Turbulence

A
  • created by wind flowing around building, rough terrain, trees
  • strong wind
65
Q

mountain waves

A
  • strong winds blows at right angles to mountain ranges
  • mountains creates barrier and the wind starts to undulate
  • create severe turbulence + aircraft is hard to control
  • stability - stable layer at height of the mountain unstable underneath and less stable layer above
66
Q

Lenticular clouds

A
  • form in the crests of the mountain waves and are less shaped
  • rotor clouds from in the rotor zone found under lenticular clouds
67
Q

hoar Frost

A
  • cruising at high altitudes for long period of time
  • airframe cools to same temperature as surrounding air (cold soaked)
  • aircraft descend into the humdi air
  • humid air contacts a/c and freezes
68
Q

Freezing Rain

A
  • flying above the freezing level
  • skin gets below zero
  • flying through rain can freeze on contact
69
Q

Icing - super cooled water droplets

3 factors to form ice

A
  • they will not connect if they are already frozen
  • small supercooled water droplets from Rime ice
  • larger super cooled water droplet from clear ice
    1. Temperature
    2. cloud type
    3. droplet size
70
Q

Rime Ice

A

0* to -15

  • small supercooled droplet, freeze instantly created a mixture of tiny particles with trapped air
  • makes the ice brittle and white
71
Q

Clear Ice

A

-10* to -39*

larger super cooled water droplet takes longer to freeze when on a/c surface

72
Q

Frost

A

forms on a/c surface over night

  • disrupt airflow, increase stall speed, TODR
  • must removed before flight
73
Q

Windshear/downburst

A
  • change in wind speed and direction with a change in height
  • downdraught from a thunderstorm - presence can be indicated by blowing dust at the surface or viagra
  • most severe turbulence from downdraught associated with thunderstorms after mature stage
74
Q

Thunderstorms Development

A
  1. high humidity
  2. atmosphere stability
  3. trigger mechanism
75
Q

Cumulus Stage

A

growing or formative stage

  • last up to 30 mins
  • stage is with updraught
76
Q

Mature Stage

A
  • updraught can no longer support rain drops

- downdraught begin to form and rain is released from the cloud

77
Q

Dissipating stage

A
  • only downdraught
  • storm is starting to fall apart
  • 30 mins
78
Q

Thunderstorm triggers

A

heat or convection -hot air rising in an unstable atmosphere
frontal = air forced to rise
Cold Stream - cold air stream that moves into a warmer environment (latitudinal hearing)
- does not rely on direct solar heating

79
Q

Nocturnal Thunderstorms

A
  • ocean retains its heating helping the bottom of the - cloud stay warm
  • tops of cloud lose heat to atmosphere
  • increase instability the cloud
80
Q

orthographic thunderstorms

A
  • mountain cause air to be lifted to trigger thunderstorms
81
Q

Thunderstorm hazards

A
  • turbulence and windshear
82
Q

low level windshear (thunderstorm hazards)

A
  • downdraught from the thunderstorm spread outwards at low level create gust fronts
  • sudden change in wind speed and direction
83
Q

hail (thunderstorm hazards)

A
  • cause serious damage to a/c
  • middle of the cloud
  • clear air underneath the cirrus anvil
84
Q

Lightining (thunderstorm hazards)

A
  • damage vis when flying in heavy precipitation is hazard to VFR a/c
85
Q

VIS (thunderstorm hazard)

A

-Reduced vis when flying in heavy precipitation is hazard to VFR a/c

86
Q

Viagra

A
  • rain evaporates before hitting the ground

- indication of downdraught/mirco burst

87
Q

Tropical Cyclone Conditions

A
  • small and intense low pressure system

- over warm ocean

88
Q

Tropical Cyclone

A
  • formative stage the centre of pressure is steadily dropping violent winds
  • pressure been falling, temperature is rising
  • central temperature risies above the dew point temperature creates the ete as the cloud no longer exists in centre
  • depression stage if the cyclone moves out of 5S and 15S (marked by torrential rain and flooding)

PPL (6 decks)

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