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Met Flashcards

(101 cards)

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1
Q

The atmosphere makeup

A

78% Nitrogen
21% Oxygen
Small amounts of inert gases

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2
Q

What is pressure measured in?

A

1hPa = 100 Pascals = 1mb

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3
Q

What are isobars?

A

Lines of constant pressure

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4
Q

ICAO standard atmosphere?

A

MSL of 1013mb, MSL temp of 15deg decreasing 1.98deg per 1000’ to 56.5deg at 36,000’, above which stays constant to 80,000’.

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5
Q
  1. QFE?
  2. .QFF?
  3. QNH?
  4. QNE?
A
  1. Alt setting for highest part of the airfield/runway.(height)
  2. MSL pressure used on weather charts
  3. MSL pressure for altimeter(altitude)
  4. Height indicated on landing when 1013.25 is set.
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6
Q

Density characteristics

A

At constant temp - density decreases as pressure decreases.

At constant pressure - density decreases as temperature increases.

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7
Q

Density altitude calculation?

A

DA = Pressure altitude + (120 x (T - 15))

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8
Q

Name the 2 types of temperature radiation.

A

Short wave and long wave.

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9
Q

Temperature profile in the atmosphere is divided into two parts. Name them.

A

Troposphere - lowest region, temp generally decreases with height and most weather exists.
Stratosphere - The region above where temperature remains constant with height.
Tropopause - The boundary layer between the two.

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10
Q

Steep Lapse rate?

A

Temperature decreases quickly with height, occurs in cold unstable airflow.

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11
Q

Shallow Lapse rate?

A

slow decrease in temperature in height, occurs in warm stable airflow.

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12
Q

Isothermal?

A

a layer where the temp remains constant with height.

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13
Q

Inversion?

A

a layer where the temperature increases with height.

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14
Q

Environmental Lapse rate?

A

The actual temp structure of the atmosphere at a specific time and place; it varies considerably

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15
Q

What are 4 types of heat transfer?

A
  1. Convection
  2. Conduction
  3. Turbulence
    4 Advection
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16
Q

What is convection?

A

occurs when warmer, less dense air moves upwards through cooler air. The cooler air sinks to replace this warmer air thus starting vertical circulation.

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17
Q

What is conduction?

A

occurs when air is warmed by contact with a warmer surface or it is cooled by contact with a cold surface.

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18
Q

What is Turbulence?

A

mixing of warming and cold air by the winds through adjacent layers.

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19
Q

Whats is advection?

A

occurs when warm or cold air is blown horizontally across the earths surface, heat transfer between the surface and air then takes place by conduction, convection or turbulent mixing, creating types of airmass that effect the UK.

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20
Q

What is adiabatic temperature change?

A

occur when a sample of air is warmed by compression or cooled by expansion with no heat added or taken away from the sample.

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21
Q

Dry adiabatic lapse rate?

A

Dry air displaced vertically in the atmosphere cools, or warms at about 3deg per 1000’

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22
Q

Saturated adiabatic lapse rate?

A

The release of latent heat reduces the rate of cooling to 1.5deg per 1000’

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23
Q

Unstable air?

A

When a parcel of air is warmer and less dense than its surroundings causing it to rise.

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24
Q

Stable air?

A

When a parcel of air is cooler than air above it. Air displace vertically tends to return to its original level.

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25
How are clouds formed?
Lifting of moist air until saturation occurs resulting in the formation of cloud. The type of cloud is controlled by the stability of the environment.
26
What is water vapour?
Odourless , transparent, gas mixes invisibly with dry air.
27
What is water liquid?
exists in form of very small water droplets in cloud and fog, small drops in drizzle and larger drops in rain.
28
What is water solid?
ice particles occurs as crystals in high cloud, amalgamation of crystals in snow, solid lumps in hail, and coating s on objects as frost, rime or clear ice.
29
What is condensation?
When vapour turns to liquid, latent heat is released.Eg cold air in contact with the window of a warm room cools the window and condensation occurs.
30
What is evaporation?
When liquid water turns to vapour, latent heat is used up.
31
What is deposition?
When vapour turns directly to solid(ice) , latent heat is released.
32
What is sublimation?
Solid turns directly to vapour. Requires latent heat
33
What is relative humidity?
The amount of water vapour contained in a mass of air expressed as a percentage compared with that which would be contained by the same mass of air if it were saturated.
34
What is due point?
The temp to which air must be cooled to become saturated.
35
What is saturation?
Air is saturated when it holds the maximum possible amount of water vapour at any particular temp and pressure.
36
Define night.
It is between the end of evening twilight and the start of morning twilight.
37
Sources of light at night?
Moonlight, Solar Light, Background illumination and Artificial light.
38
What is a veering wind?
a change in a clockwise direction, ie W to NW.
39
What is a backing wind?
A change in a anticlockwise direction, IE S to SE
40
What is BUYS BALLOTS LAW?
With your back to the wind, low pressure will be on your left in a northern hemisphere.
41
Pressure gradient force?
Unequal pressure distribution acting from high to low pressure.
42
What is coriolis?
A force caused by the spin of the Earth.
43
What is Geostrophic flow?
result of balanced flow along straight parallel isobars with no friction. Caused by a balance between pressure gradient force and coriolis.
44
Surface wind?
Generally slacks and backs.
45
What is a Gust?
Short period, small-scale fluctuations of surface wind.
46
What is a Squall?
Sudden increase of win speed by at least 16-22 kts or more, lasting for at least one minute distinguished from gusts by their longer duration.
47
Define sea breeze.
Differential heating may cause lower pressure over land than adjacent sea. Air then moves inland. It may add to , or reverse existing light surface winds.
48
Valley wind?
Air prefers to flow around rather than over over hills. The venturi or funnel effect will accelerate the air giving stronger winds.
49
What is Fohn wind?
A warm dry wind to lee of a mountain range.
50
What is Katabatic Wind?
Air in contact with cold, sloping ground becomes denser than air at the same level and then flows DOWNHILL.
51
Whats is Anabatic Wind?
Light UP-SLOPE flow over heated slopes in daytime.
52
What is a Gale?
Wind of mean speed of 34kts or more over 10 minutes.
53
Define visibility.
The greatest horizontal distance at which objects can be seen and recognized under conditions of ordinary daytime, commonly abbreviated to VIS.
54
What is prevailing visibility?
The most common visibility seen by the observer rather than the lowest.
55
How is radiation fog formed?
Cooling due to radiation from the ground on clear nights with winds less than 10kts, chiefly in anticyclone weather.
56
How is advection fog over land caused?
Cooling of warm air by movement over cold ground occurs when warm air arrives after a cold spell.
57
How is advection fog over sea formed?
Cooling of warmer air by movement over colder surfaces.
58
How is Frontal Fog formed?
Near fronts due to lowering of clouds in rain and mixing of moist airmasses vat different temperatures.
59
How is hill fog formed?
By adiabatic cooling and by movement of low cloud onto hills.
60
How is smoke fog formed?
In conditions similar to radiation fog, especially in stable air.
61
Name the 5 types of precipitation.
1. Drizzle 2. Rain 3. Snow 4. Sleet 5. Hail
62
What are cloud amounts measured in?
Oktas
63
What are the trigger actions for the ascent of air
1. Frontal lifting 2. Orographic lifting 3. Turbulant mixing 4. Convection 5. Convergence
64
Name the low level clouds
ST - Stratus SC - Stratocumulus CU - Cumulus CB - Cumulonimbus
65
Name the medium level clouds.
AC - Altocumulus AS - Altostratus NS - Nimbostratus
66
Name the high level clouds
CI - Cirrus CS - Cirrostratus CC - Cirrocumulus
67
At what height would you find high cloud?
20-40,000'
68
At what height would you find medium cloud?
6500 - 20,000'
69
At what height would you find low level cloud?
1000 - 6500'
70
How are clouds using Oktas measured?
1-2 Few 3-4 Scattered 5-7 Broken 8 Overcast
71
Name the two types of thunderstorms
Airmass and frontal
72
What are the conditions required for a thunderstorm?
1. Plentiful amount of moisture. 2. A deep layer of unstable air. 3. Unstable layer extending well above the 0deg level. 3. Trigger action.
73
Trigger action to create a thunderstorm?
1. Thermal - Convection due to surface heating 2. Orographic - forced uplift over high ground 3. Frontal - uplift of air at a front 4. Convergence - with falling surface pressure convergence of low level winds causes forced ascent
74
Hazards of a thunderstorm
``` Icing Hail lightning Strong vertical currents Turbulence Electrical effects Poor visibility Wind sheer ```
75
Name the types of ice
1. Hoar frost 2. Rime ice 3. Clear Ice 4. Rain Ice 5 Packed snow
76
Effects of icing on aircraft.
1. Aerodynamics 2.Control rods and surfaces. 3. Weight 4. Miscellaneous - obstruction of windscreen etc 5. Instruments - blockages / aerials 6 Block intakes 7. Engine icing 8. Autorotation
77
Lux to millilux ratio?
1 to 1000
78
Name the 4 types of fronts.
1. Cold front 2. Warm front 3. Occlusion 4. Quasi-stationary
79
What is an airmass?
Relatively homogeneous volumes of air covering very large areas with little horizontal variation of humidity or temperature
80
Name the UK airmass's
1. Tropical maritime 2. Tropical continental 3. Polar maritime 4. Polar continental 5. Arctic maritime 6. Returning polar maritime
81
What is a anticyclone?
High pressure, a pattern of closed isobars around sea level pressure which is relatively higher than its surroundings.
82
Whats is a COL?
A slack pressure field between to opposite areas of high pressure and two areas of low pressure with variable winds.
83
How are condensation trails formed?
Water emitted through the aircraft exhaust system is sufficient to raise the relative humidity of the air, in the wake of the aircraft, to saturation point.
84
Jet stream?
A narrow core of strong winds in the upper atmosphere characterized by marked decrease of speed above, below and to each side of the maximum velocity.
85
What is a METAR
Meteorological Aerodrome report is an actual weather report set out in the international code.
86
Whats is a TAF
Terminal Airfield Forcasts are issued as routine for selected airfields. It is a forcast covering a period of 9 hours and some have a routine issue every 3 hours.
87
Minimum weather conditions for Blue
2500' and 8km
88
Minimum weather conditions for White
1500' and 5km
89
Minimum weather conditions for Green
700' and 3.7km
90
Minimum weather conditions for Yellow 1
500' and 2.5km
91
Minimum weather conditions for Yellow 2
300' and 1.6km
92
Minimum weather conditions for Amber
200' and 0.8km
93
Minimum weather conditions for Red
<200 and <0.8km
94
Minimum weather conditions for Black
Airfield not usable for reasons other than cloud and/or visibility minima.
95
Decode BC , BR, BL and DR
``` BC = Patches BR = Mist BL = Blowing DR = Drifting ```
96
Decode DU, DZ, FC and FG
``` DU = Dust DZ = Drizzle FC = Funnel Cloud FG = Fog ```
97
Decode FU, FZ, GR and GS
``` FU = Smoke FZ = Freezing GR = Hail GS = Small hail ```
98
Decode IC, MI, PE, PO and HZ
``` IC = Diamond dust MI = Shallow PE = Ice pellets PO = dust whirl HZ = Haze ```
99
Decode PR, RA, RE and SG
``` PR = Partial RA = Rain RE = recent SG = Snowgrains ```
100
Decode SH, SN, SQ and SS
``` SH = Shower SN = Snow SQ = Squal SS = Sandstorm ```
101
Decode TS, VA and VC
``` TS = Thunderstorms VA = Volcanic Ash VC = in vicinity ```

Aviation Revision (6 decks)

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