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PPL-MET Flashcards

(98 cards)

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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
what is the dew point temperature
the temperature at which saturation occurs
25
to reach saturstion, a parcel of air with high relative humidity requires....
just a little amount of cooling
26
when is a cloud formed
when a parcel of air is cooled to its dew point temperature
27
what is the adiabatic process
changes in pressure resulting in a change in temperature
28
what is the dry adiabatic lapse rate
unsaturated air will cool at 3/1000
29
what is the saturated adiabatic lapse rate
1.5/1000
30
what are the four core triggers of unstable air
convection orographic uplift widespread ascent turbulence and mixing of air
31
what pressure systems is stable air often associated with
high pressure systems
32
what is frontal uplift
when a cold and hot front meet, the hot front rises above the cold front
33
what is orographic uplift
like the precursor to fohn wind, it flows up a mountain, and reaches the dewpoint temperature, thus causing clouds to occur.
35
what height are high level cloud bases
25000 ft and above
36
what height are medium level cloud bases
7500-20000 ft
37
what height are low level cloud bases
below 7500 ft
38
describe cirrus clouds
high level no chance of icing little turbulence
39
describe cirrostratus clouds
high level too high for significant icing little turbulence
40
describe cirrocumulus clouds
high level turbulent too high for significant icing looks grainy
41
describe altostratus clouds
medium level virga some turbulence some icing risk
42
describe thick altostratus clouds
Medium level snow/ice light turbulence in cloud heavy/moderate turbulence at fronts
43
describe thin altostratus
Medium level Virga Little turbulence Medium ice risk
44
describe altocumulus
Medium level light turbulence nil icing
45
describe lenticular altocumulus
Medium level Light rime ice forms on mountain ridges strong turbulence
46
Describe altocumulus castellanus
medium level moderate to severe turbulence indicator of unstable moist air possible thunderstorms forming
47
Describe cumulus
Low level cauliflower | light/moderate turbulence\little ice risk
48
Describe Towering cumulus clouds
sign of instability moderate/severe turbulence in andbelow definite ice risk
49
Describe Cumulonimbus
``` Cellular Large vertical component Anvil shaped Severe turbulence in and below snow hail definite icing risk ```
50
Describe stratocumulus
Baked buns light / moderate turbulence drizzle
51
describe stratus cloud
flat cloud
52
describe nimbostratus cloud
low/medium level grey continuous rain definite icing risk
53
describe mammatus BASE
not a cloud, but a base | seen after a thunderstorm
54
What differentiates stratus cloud from fog
stratus cloud is basically fog that is above 50ft AGL
55
What is virga
rain that experiences a phase change into vapour before it touches the ground
56
how long do showers last for
15-30 minutes
57
How long does intermittent precipitation last for
up to 50 minutes
58
How long does continuous precipitation last for
> 50minutes
59
What (who) do we need for a thunderstorm to form
Trigger Instability Moisture
60
What are the types of thunderstorms
``` Frontal/squall line thunderstorms Nocturnal Equatorial thunderstorms Cold stream thunderstorms Orographic thunderstorms Thermal convective thunderstorms Convergence thunderstorms ```
61
What are the stages of development for a thunderstorm
Growing stage Mature stage Dissipation stage
62
What winds are associated with each stage of the thunderstorm
Growing: Updrafts Mature: Updrafts and downdrafts Dissipation: Downdrafts
63
The effects of a thunderstorm can be felt from how far away
10 miles
64
How can you generally describe a microburst
Localised areas of INTENSE downdrafts
65
What is mechanical turbulence
Eddies (turbulence) that forms as a result of air flowing over objects
66
To what height can mechanical turbulence be felt
20 times the height of the object it passed over
67
How long do dust-devils last for, and what is their height reach?
30-60 min, 7000ft AGL
68
What are mountain waves
Critical turbulence on the lee side of a mountain
69
what is a good indicator that mountain waves are present
Lenticular waves forming at the crest of a mountain
70
When do you have to report windshear
ALWAYS
71
Would an aircraft taking off or landing produce the most wake turbulence
Aircraft taking off (less flap results in more wake turbulence)
72
when is ice-fog formed
when the temperature is less than -20
73
When is advectionfog formed
when warm moist air flows over a cool surface and reaches its dew-point temperature
74
What is an occluded front
Cold and warm front collision
75
What are the three core types of global circulation
Polar cell Tropical (convective cell) Subtropical cell (causes as a result of the other two cells)
76
What pressure system can be expected at the equatorial trough
Low pressure system
77
What pressure system can be expected at the subtropical range
High pressure system
78
What pressure system can be expected at the poles
High pressure system
79
What direction does a convergent pressure system move in
inwards from the bottom
80
What direction does a divergent pressure system move in
Outwards from the bottom
81
what is a ridge
elongated finger for high pressure systems
82
what is a trough
elongated finger for a low pressure system
83
what is a col
are between high and low pressure systems
84
what us the coriolis force
air appears to accelerate as it moves away from the equator (because the equator has a higher velocity than southern or northern parts).
85
what pressure system is the Coriolis force associated with
high pressure system
86
when does the coriolis force cease to exist
+\- 5 degrees of the equator
87
airflow that flows parallel to isobars is known as...
geostrophic wind
88
what direction does a high pressure flow in the southern hemisphere
anticlockwise
89
what direction does a low pressure flow in the southern hemisphere
clockwise
90
direction of backing
left
91
direction of veer
right
92
over land, what is the strength reduction and veer value
2/3 and 30 degrees
93
over sea, what is the strength reduction and veer value
1/3 and 10 degrees
94
what temp is rime ice most common in
-10 -20
95
what temp is good for cyclone breeding
28 degrees
96
what coordinates are cyclones commom
5 and 15 degrees south latitude
97
what is a key difference in the stages of a cyclone
pressure (lower pressure for more severe conditions)
98
weather changes associated with a cold front
rise in pressure drop in temp dew point after passing will be lower

Aviation (12 decks)

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