Meteorology Flashcards
(89 cards)
1
Q
Troposphere
A
Temperature decreases with height, up to tropopause (11km, 36,090ft).
Lapse rate is 1.98c per 1000ft/0.65c per 100m
2
Q
Tropopause
A
Polar tropopause: lower and warmer
Equatorial tropopause: higher and colder
3
Q
Tropopause breaks
A
At around 30deg and 60deg latitude in both hemispheres
Is due to difference in air temp
4
Q
Stratosphere
A
11km-50km
Temp is constant to c.20km/65,600ft. Increases from 30km-50km due to ozone o3 present.
O3 absorbs shortwave radiation from sun, helping to shield the earth.
5
Q
Polar stratospheric cloud
A
Aka nacreous cloud or “mother of pearl”.
Appears sometimes in stratosphere.
6
Q
Mesosphere
A
Temperature decreases with height
Up to 80km high, temp to -90c at mesopause.
7
Q
Polar mesospheric clouds
A
Appear very rarely in mesosphere. Aka noctilucent cloud.
8
Q
Thermosphere
A
Temp increases with height up to 2000c
Contains ionosphere.
9
Q
Ionosphere
A
Sits within thermosphere.
Electrostatic energy varies between 200kv-500kv between ionosphere and earths surface.
10
Q
ISA Values at MSL
A
Temp: 15c
Density: 1225g/m3
Pressure: 1013.25hpa, 760mm mg.
11
Q
ISA Temp Lapse Rate
A
1.98c per 1000ft up to 36,090ft
Constant from 36,090ft to 20km (65,600ft)
12
Q
Pressure levels (10k, 18k, 30k, 38k, 53k ft)
A
10,000ft: 700hpa 18,000ft: 500hpa (50% MSL) 30,000ft: 300hpa 38,000ft: 200hpa 53,000ft: 100hpa
13
Q
Pressure changes (0ft-20000ft and 20,000ft +)
A
0ft-20,000ft: 27ft per hpa/8m per hpa
20,000+: 50ft per hpa/15m per hpa
14
Q
Calculating lapse rate (equation)
A
H = 96xTk / P
15
Q
ISA density rates (10k, 22k, 40k ft)
A
MSL: 1.225Kg/m3
10,000ft: 0.903kg/m3
22,000ft: 0.609kg/m3
40,000ft: 0.302kg/m3
16
Q
Insolation
A
Heating of earths surface by the sun
17
Q
Terrestrial radiation
A
Long wave heat from the earth, heating the atmosphere
18
Q
Conduction
A
Transfer of heat by direct physical contact from one surface to another
19
Q
Convection
A
Vertical transfer of heat
20
Q
Advection
A
Horizontal transfer of heat. I.e. by wind.
21
Q
June solstice (date, latitude, tropic)
A
21 Jun
23.5deg north
Tropic of Cancer
22
Q
December solstice (date, latitude, tropic)
A
21 December
23.5deg south
Tropic of Capricorn
23
Q
Inversion
A
Where cold air can’t escape from below warm air. Occurs under clear skies and at morning.
24
Q
Frontal inversion
A
When two fronts meet. Cold air trapped under warm.
25
Subsidence inversion
High pressure inversion. Caused by sinking cold (but warming) air, which settles above the cold ground level air.
26
Simple aneroid barometer
Used to measure pressure in aircraft altimeter.
27
Periphelion
4 Jan. Earth is closest to the sun @ 91million Miles
28
Aphelion
4th July. Earth is furthest from the sun @ 95million Miles
29
Specific heat property of land
Low Specific heat energy as it takes less joules to change 1 gram of surface temperate by 1kelvin
30
Specific heat property of water
High specific heat property as it takes higher amount of joules to heat 1g of water by 1kelvin
31
Latent heat process (water vapour-ice)
Latent heat is released.
Water vapour-(condensation)-water-(freezing)-ice
Water vapour-(freezing)-ice: sublimation (e.g frost.)
32
Latent heat (ice-water vapour)
Latent heat is absorbed
Ice-(melting)-water-(evaporation)-water vapour.
Ice-(evaporation)-water vapour: sublimation (I.e. freezer on beach on hols!).
33
Which direction does a high pressure wind move in the northern hemisphere?
Clockwise
34
Which direction does a low pressure wind move in the northern hemisphere?
Anti-clockwise
35
What happens to the pressure of cold air with increased height?
The pressure in cold air decreases more rapidly with height
36
What happens to the pressure in warm air with height?
The pressure in warm air decreases slower with height, compared to ISA
37
What is Regional Pressure Setting (RPS)?
A regional pressure setting covers a local area and is measured by the lowest pressure setting within that region.
It is valid for a period of 1 hour.
38
What is the transition altitude?
Transition altitude is the highest level at which RPS may be used, based on QNH.
It sits below the transition layer.
39
What is transition level?
Transition level is the minimum level at which SPS may be used and is based on 1013.2hpa.
40
What is the transition layer?
The transition layer separates the transition altitude and the transition level.
41
What is the Temperature Error Correction formula (TEC)?
For every 10deg deviation from ISA, apply a 4% correction of the indicated altitude.
This should only be applied to the distance of the aircraft above the ground.
42
What factors affect density? (X 3) and what factor has the biggest effect on density?
Pressure, temperature and humidity.
Pressure has the biggest effect on density and is proportional.
43
What effect does temperature have on air density?
Temperature is inversely proportional density.
As temperature increases, air density decreases.
44
What are the air density levels? (MSL; 10,000; 22,000; 40,000ft)
MSL: 1.225kg/m3
10,000ft: 0.903kg/m3
22,000ft: 0.609kg/m3
40,000ft: 0.302kg/m3
45
What is the method for calculating density altitude?
For every 1c deviation from ISA Temperature, the density altitude differs from the ISA Pressure Altitude by 120ft.
46
What latitudes does the ITCZ sit?
The ITCZ deviates to approx 23.5deg north and south.
47
What type of pressure system is found at the equator?
The equator experiences a low pressure system, due to high insolation causing mass convection of air.
48
What causes a large scale thermal low?
A low pressure thermal low is caused by insolation creating rising air.
49
What causes a polar air depression?
A polar air depression is caused by thermal lows in winter due to the sea being relatively warmer than land masses. I.e gulf of Alaska, the Norwegian Sea and Sea of Japan.
50
When would an orographic low occur?
An orographic low occurs on the leeward side of large features, where a relatively high pressure goes around the feature, compared to a relative low behind said feature.
51
What is the definition of a warm high?
A warm high is when the centre of the pressure system is relatively higher pressure than the rest of the system
52
When would a cold high occur?
A cold high occurs when the centre of a high pressure system is relatively cold at the upper centre.
53
How is humidity measured?
Humidity is measured using a hygrometer or a psychrometer (w+d bulb thermometer).
54
What is saturation?
Saturation is the maximum amount of water vapour a parcel of air can hold.
Cold air can hold less water vapour than warm air.
55
What are the three main types of cloud classification?
Cumuliform (unstable air, towering in appearance)
Statifom (stable air, flat in appearance)
Cirrus (high)
56
What does WMO stand for?
World meteorological organisation
57
What level is low, middle and high cloud in temperate regions?
Low: surface-6500ft
Middle: 6500ft-23000ft
High: 16500-45000ft
58
What is the most hazardous region for icing to occur?
Between 0c and -20c.
59
What are the 5 types of cloud coverage referred to as? (SKC...)
0 OKTAS - SKC
1-2 OKTAS - FEW
3-4 OKTAS - SCT
5-7 OKTAS - BKN
8 OKTAS - OVC
60
How often is a METAR issued?
Every one hour.
61
What is a cello meter used for?
To measure cloud base via a laser
62
What are the three types of Cirro cloud?
Cirrus (Ci)
Cirrostratus (Cs) - these give a halo effect.
Cirrocumulus (Cc)
63
What are the two types of middle cloud (alto)?
Altostratus (As) - layered cloud
Altocumulus (Ac) - pebble shape
64
What are the five types of low cloud (stratus)?
Stratus (St) - grey and layered.
Stratocumulus (Sc) - mixture of low level stratus and cumulus
Nimbostratus (Ns) -darker grey. Rain bearing.
Cumulus (C) - low level convective cloud
Cumulonimbus (Cb) - rainy cumulus cloud which extends to tropopause.
65
What are the 4 towering stages for a CB?
Cumulus humilus (below 10000ft)
Cumulus mediocris (Cu Med) max height 10000ft
Cumulus Congestus (TCU) up to 25000ft
Cumulonimbus (calvas- moisture) or capilatus (Cb Cap - ice crystals).
66
What are the 5 cloud descriptors for CB within SIGWx?
```
ISOL - ISOLATED
OCNL - OCCASIONAL
FRQ - FREQUENT
EMBD - EMBEDDED
WDSPD - WIDESPREAD
```
67
What is coalescence theory?
Coalescence theory is that precipitation forms in clouds warmer than 0c
68
What temperatures does snow fall?
+4c to -5c
69
What type of clouds do snow grains fall from?
Stratiform clouds.
70
What are the three types of precipitation?
Light
Moderate
Heavy
71
What are the 6 categories for vis in precipitation?
```
Heavy snow - less than 50m
Drizzle - less than 500m
Moderate snow - less than 1000m
Heavy rain = 1000m
Moderate rain 3-10km
```
SURFACE BLOWN SNOW CAN GREATLY REDUCE VISIBILITY.
72
What are the three required triggers for a thunderstorm?
Instability
Moisture
Trigger
73
What are the five types of thunderstorm?
```
Heat
Air mass
Squall line
Frontal
Orographic
```
74
What are the three stages of the life cycle of a thunderstorm?
Building phase (updraft 60kts). 15-20 mins
Mature phase (updraft and downdraft exist) up to 100kts updraft; precipitation. Lasts 15-20mins
Dissipating stage (downdraft only; heavy precip; lasts 2-2.5hrs)
75
What is a squall line?
A squall line is a line of individual thunderstorm cells.
76
What is a mesoscale corrective area (MCA)?
A MCA is a group of Cu/Cub developments. They sometimes form on the equatorial trough.
MCAs cover 100-1000 miles and last 1-2 days.
77
What are the four types of lightning?
Cloud to air (CA)
Cloud to ground (CG)
Intra Cloud (IC)
Cloud to cloud (CC)
78
What wind speeds can you expect in tornadoes?
Wind speed can exceed 200kts within the tornado
79
What speeds do tornadoes travel across the ground?
20-40kts
80
How long do tornadoes last and what is their typical diameter?
Tornadoes last roughly 30mins and are 100-150vmetres wide
81
What does ARWD stand for?
Airborne Weather Radar Detector
82
What are the thunderstorm avoidance measurements for both above and below 20,000ft (width and height clearance)
Above 20,000ft: 20 miles on all sides and 5000ft vertically
Below 20,000ft: 10,000ft laterally and 5000ft vertically
83
What are the four stages of a tropical storm development?
Tropical disturbance
Tropical depression
Tropical storm
Tropical revolving storm
84
What winds would you expect in a tropical disturbance; tropical depression; tropical storm; tropical revolving storm?
Tropical disturbance: light winds c20kts
Tropical depression: 20-33kts
Tropical storm: 34-63kts. Cloud formation
Tropical revolving storm: 64kts +
85
What sea temperature is required for a TRS to develop?
The sea must be at least 26.5c
86
How wide are TRS? (Tropical Revolving Storm)
TRS are 500-2000km. They are a large scale heat low.
87
How wide is the eye of the storm in a TRS?
The eye of the storm is roughly 20-50km
88
What direction do Tropical Revolving Storms travel?
TRS travel from East to West in both hemispheres.
89
What temperatures do both large and small SCWD normally form?
Large SCWD: 0c to -20c
Small SCWD: -20c to -40c
