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Aviation > PPL-MET > Flashcards

PPL-MET Flashcards

0
Q

what layer contains the ozone layer

A

stratosphere

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1
Q

in the troposphere, what percentage is water

A

0-5%

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2
Q

what easily produces ozone

A

high voltage electrical arc

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3
Q

what are the ISA standards

A

1013.25 Hpa
15 degrees c
1225 grams/m^3

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4
Q

at what height is the density approximately half that of sea level

A

20,000 ft

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5
Q

what are three ways heat is transferred

A

radiation
absorbtion
conduction

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6
Q

what is advection

A

horizontal wind

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7
Q

why do we get a sea breeze

A

low pressure system on land, high pressure system of sea air fills gap, thus creating wind.

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8
Q

why do we get a land breeze

A

land cools faster than sea, therefore higher pressure over land moves in to replace low pressure air over sea

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9
Q

which is stronger, sea breeze or land breeze

A

sea breeze

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10
Q

what is katabatic wind

A

air that is cooled down, and then flows down slopes as a result of the force of gravity

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11
Q

when is katabatic wind strongest

A

dawn

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12
Q

what is anabatic wind

A

air heats up and rises to replace air that has gone down (cuz it cooled down)

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13
Q

why is anabatic wind weaker than katabatic wind

A

because it has to oppose the force of gravity

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14
Q

what causes fohn wind

A

air rises up a mountain, loses its moisture through rain/precipitation, and then heats up as it goes down the other side of the mountain. it doesn’t rise because the density of air is GREATER than that of water vapour.

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15
Q

what causes low level jet streams

A

high pressure system coming into contact with mountains, thus creating a Venturi effect.

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16
Q

what speed can low level jet-streams reach

A

70 kts

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17
Q

at what altitude are low level jet streams expected, and at what altitude are they strongest

A

< 3000 ft, 2000 ft

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18
Q

in terms of low level jet streams, why does wind speed increase during the night

A

the air cools, and provides a layer with less friction for the winds to pass over, thus creating faster winds

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19
Q

which direction do low level jet streams usually come from in aus

A

the south

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20
Q

what is sublimation

A

phase change from solid to gas

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21
Q

what is the equation for relative humidity

A

(vapour present/vapour possible) X 100%

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22
Q

what does it mean when air is said to be saturated

A

when the amount of water vapour present is such that the parcel of air cant hold anymore

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23
Q

what are the two ways for air to reach the saturated state

A

at a constant temperature, water can be added

with a constant amount of water, reduce the temperature

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24
Q

what is the dew point temperature

A

the temperature at which saturation occurs

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25
Q

to reach saturstion, a parcel of air with high relative humidity requires….

A

just a little amount of cooling

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26
Q

when is a cloud formed

A

when a parcel of air is cooled to its dew point temperature

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27
Q

what is the adiabatic process

A

changes in pressure resulting in a change in temperature

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28
Q

what is the dry adiabatic lapse rate

A

unsaturated air will cool at 3/1000

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29
Q

what is the saturated adiabatic lapse rate

A

1.5/1000

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30
Q

what are the four core triggers of unstable air

A

convection
orographic uplift
widespread ascent
turbulence and mixing of air

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31
Q

what pressure systems is stable air often associated with

A

high pressure systems

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32
Q

what is frontal uplift

A

when a cold and hot front meet, the hot front rises above the cold front

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33
Q

what is orographic uplift

A

like the precursor to fohn wind, it flows up a mountain, and reaches the dewpoint temperature, thus causing clouds to occur.

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35
Q

what height are high level cloud bases

A

25000 ft and above

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36
Q

what height are medium level cloud bases

A

7500-20000 ft

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37
Q

what height are low level cloud bases

A

below 7500 ft

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38
Q

describe cirrus clouds

A

high level
no chance of icing
little turbulence

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39
Q

describe cirrostratus clouds

A

high level
too high for significant icing
little turbulence

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40
Q

describe cirrocumulus clouds

A

high level
turbulent
too high for significant icing
looks grainy

41
Q

describe altostratus clouds

A

medium level
virga
some turbulence
some icing risk

42
Q

describe thick altostratus clouds

A

Medium level
snow/ice
light turbulence in cloud
heavy/moderate turbulence at fronts

43
Q

describe thin altostratus

A

Medium level
Virga
Little turbulence
Medium ice risk

44
Q

describe altocumulus

A

Medium level
light turbulence
nil icing

45
Q

describe lenticular altocumulus

A

Medium level
Light rime ice
forms on mountain ridges
strong turbulence

46
Q

Describe altocumulus castellanus

A

medium level
moderate to severe turbulence
indicator of unstable moist air
possible thunderstorms forming

47
Q

Describe cumulus

A

Low level cauliflower

light/moderate turbulence\little ice risk

48
Q

Describe Towering cumulus clouds

A

sign of instability
moderate/severe turbulence in andbelow
definite ice risk

49
Q

Describe Cumulonimbus

A 
Cellular
Large vertical component 
Anvil shaped 
Severe turbulence in and below
snow
hail
definite icing risk
50
Q

Describe stratocumulus

A

Baked buns
light / moderate turbulence
drizzle

51
Q

describe stratus cloud

A

flat cloud

52
Q

describe nimbostratus cloud

A

low/medium level
grey
continuous rain
definite icing risk

53
Q

describe mammatus BASE

A

not a cloud, but a base

seen after a thunderstorm

54
Q

What differentiates stratus cloud from fog

A

stratus cloud is basically fog that is above 50ft AGL

55
Q

What is virga

A

rain that experiences a phase change into vapour before it touches the ground

56
Q

how long do showers last for

A

15-30 minutes

57
Q

How long does intermittent precipitation last for

A

up to 50 minutes

58
Q

How long does continuous precipitation last for

A

> 50minutes

59
Q

What (who) do we need for a thunderstorm to form

A

Trigger
Instability
Moisture

60
Q

What are the types of thunderstorms

A 
Frontal/squall line thunderstorms
Nocturnal Equatorial thunderstorms
Cold stream thunderstorms
Orographic thunderstorms
Thermal convective thunderstorms
Convergence thunderstorms
61
Q

What are the stages of development for a thunderstorm

A

Growing stage
Mature stage
Dissipation stage

62
Q

What winds are associated with each stage of the thunderstorm

A

Growing: Updrafts
Mature: Updrafts and downdrafts
Dissipation: Downdrafts

63
Q

The effects of a thunderstorm can be felt from how far away

A

10 miles

64
Q

How can you generally describe a microburst

A

Localised areas of INTENSE downdrafts

65
Q

What is mechanical turbulence

A

Eddies (turbulence) that forms as a result of air flowing over objects

66
Q

To what height can mechanical turbulence be felt

A

20 times the height of the object it passed over

67
Q

How long do dust-devils last for, and what is their height reach?

A

30-60 min, 7000ft AGL

68
Q

What are mountain waves

A

Critical turbulence on the lee side of a mountain

69
Q

what is a good indicator that mountain waves are present

A

Lenticular waves forming at the crest of a mountain

70
Q

When do you have to report windshear

A

ALWAYS

71
Q

Would an aircraft taking off or landing produce the most wake turbulence

A

Aircraft taking off (less flap results in more wake turbulence)

72
Q

when is ice-fog formed

A

when the temperature is less than -20

73
Q

When is advectionfog formed

A

when warm moist air flows over a cool surface and reaches its dew-point temperature

74
Q

What is an occluded front

A

Cold and warm front collision

75
Q

What are the three core types of global circulation

A

Polar cell
Tropical (convective cell)
Subtropical cell (causes as a result of the other two cells)

76
Q

What pressure system can be expected at the equatorial trough

A

Low pressure system

77
Q

What pressure system can be expected at the subtropical range

A

High pressure system

78
Q

What pressure system can be expected at the poles

A

High pressure system

79
Q

What direction does a convergent pressure system move in

A

inwards from the bottom

80
Q

What direction does a divergent pressure system move in

A

Outwards from the bottom

81
Q

what is a ridge

A

elongated finger for high pressure systems

82
Q

what is a trough

A

elongated finger for a low pressure system

83
Q

what is a col

A

are between high and low pressure systems

84
Q

what us the coriolis force

A

air appears to accelerate as it moves away from the equator (because the equator has a higher velocity than southern or northern parts).

85
Q

what pressure system is the Coriolis force associated with

A

high pressure system

86
Q

when does the coriolis force cease to exist

A

+- 5 degrees of the equator

87
Q

airflow that flows parallel to isobars is known as…

A

geostrophic wind

88
Q

what direction does a high pressure flow in the southern hemisphere

A

anticlockwise

89
Q

what direction does a low pressure flow in the southern hemisphere

A

clockwise

90
Q

direction of backing

A

left

91
Q

direction of veer

A

right

92
Q

over land, what is the strength reduction and veer value

A

2/3 and 30 degrees

93
Q

over sea, what is the strength reduction and veer value

A

1/3 and 10 degrees

94
Q

what temp is rime ice most common in

A

-10 -20

95
Q

what temp is good for cyclone breeding

A

28 degrees

96
Q

what coordinates are cyclones commom

A

5 and 15 degrees south latitude

97
Q

what is a key difference in the stages of a cyclone

A

pressure (lower pressure for more severe conditions)

98
Q

weather changes associated with a cold front

A

rise in pressure
drop in temp
dew point after passing will be lower

Aviation (12 decks)

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