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Met > Facts > Flashcards

Facts Flashcards

1
Q

Speeds for a tropical depression, storm and cyclone

A

Depression - 20 to 33kts
Storm - rotating 34 to 63kts
Cyclone - above 64 kts

They all travel at 15 to 20 kts across the surface

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2
Q

Gale,storm and hurricane wind speeds

A

Gale - 34 to 47kts
Storm - 43 to 63kts
Hurricane +64kts

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3
Q

Calculating density altitude

A

Apply 120ft for every 1c isa dev

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4
Q

Absolute humidity

A

Amount of water vapour in a volume of air

G/m3

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5
Q

GR diameter

A

5-50mm, highest recorded is 1kg

Small hail is less than 5mm

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6
Q

Back bent occlusion

A

Extend from the centre of depression where the occlusion starts

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7
Q

Sea breeze speed and average height

A

10kts in mid lats

10-15 miles inland and up to 1000 ft amsl

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8
Q

Northerly winds from n Africa

A

Scirocco
Khamsin
Ghibli

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9
Q

Deflection of the surface wind and the % of the speed of the 3000ft winds

A

Over sea - 10* 70%

Land by day - 30* 50%

Land by night - 45* 25%

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10
Q

Temp where there is mostly ice particles

A

Below -40

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11
Q

Hight of the tropopause at the equator and poles and the associated temps

A

Poles = 26,000ft/8km/ -50c

Equator = 60,000ft/18km/-75c

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12
Q

Why is wind speed faster around a high

A

Centrifugal force acts with the PGF

Works against PGF in a low

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13
Q

Humidity mixing ratio

A

Amount of water vapour in a mass of dry air

G/kg

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14
Q

PGF + CF are equal and opposite

A

Geostrophic wind

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15
Q

What happens if rising cools without any condensation nuclei

A

The air is super saturated at a temp above 0c

SCWD are former below 0c

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16
Q

Height of the different satellites

A

Geostationary 35,786km , poor resolution, identify TRS

Polar orbiting 850km and orbit daily, high resolution

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17
Q

Routine reports

A

Metar
L/d forecast/trend
Speci - change in operational significance

All issued by meteorological stations aerodrome based

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18
Q

Heights and lats of the jet streams

A

Sub trop - fl400, 30 - 40 n/s

Polar front - FL300, 50 - 60 n/s

Arctic - fl200, 70n

Equatorial/easterly - fl500, 10 -20 n

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19
Q

ISA temp lapse rate in m

A

0.65c/100m

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20
Q

Visibility in cloud

A

Low level 10 - 30m
Mid 20 - 1000m
High +1000m

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21
Q

Lines of equal wind speed

A

Isotachs

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22
Q

Rain ice

A

Clear ice

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23
Q

What is required to form a TRS and what is their track

A

Sea temp min 26.5 and 200 to 300ft deep and a trigger - easterly waves within 5 - 25 deg n and s
Travel westward and curve away from the equator and head east

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24
Q

Length of Turbulence after mountain wave and vertical wind speed

A

50 - 100nm downwind

Vertical windspeed 1000ft/min, waves 1500 ft deep

Higher the mountain, stronger the wave

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25
Q

Height of a transmissometer

A

7.5ft up

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26
Q

Finding qnh alt

A

Ta-(isa dev x 4 x FL/1000)

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27
Q

Examples of orographic depressions

A

Alps in n Italy in winter

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28
Q

Ts avoidance

A

20nm over 20,000ft

10nm If below

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29
Q

What measures ELR

A

Radiosonde

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30
Q

What is classed as a gust

A

Sudden increase in windspeed of +10kts

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31
Q

Equipment to measure humidity

A

Psychrometer

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32
Q

Anemometer

A

Measures surface wind, 10m up

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33
Q

Type of cloud with people mountain wave

A

Cap,lenticular,rotor or roll cloud

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34
Q

Haze

A

Less than 5000m

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35
Q

Temp to form snow

A

+4 to -5c

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36
Q

How fast does the warm front travel at

A

Travels at 2/3 speed of the cold front, so it always catches up with the warm front and forms an occlusion

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37
Q

What % of USA hurricanes develop from easterly waves

A

80%

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38
Q

Most common type of inland fog

A

Radiation

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39
Q

Equipment to detect lightning

A

Stormscope, strikefinder

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40
Q

Finding true altitude

A

Qnh alt + (isa dev x 4 x FL/1000)

41
Q

Average height of the spheres

A

Troposphere- 11km
Strato - 50km
Meso - 80km/ -90c

42
Q

How long is rvr averaged for

A

1min for ATC and 10mins for metar/taf

43
Q

Routine forecasts

A

Taf, produced by meteorological offices all over the world
Sigwx, produced by the world area forecast centres

gamet - low level forecast, gafor- low level vis/cloud

44
Q

How often does a rvr update

A

Every 60s

45
Q

Cb calvus

A

Developing ts cloud

46
Q

Intermittent precipitation

A

Continuous with breaks

47
Q

Classification of cloud coverage

A 
0 - SKC 
1-2 FEW 
3-4 SCT
5-7 BKN
8 - OVC
48
Q

Temp range where the most SCWD are found

A

0 to -10c

49
Q

Warm occlusion

A

Warm front is colder than air behind

Precipitation falls ahead of the occlusion

50
Q

Dominant pressure systems

A

Jan - Siberian, Canadian highs, Icelandic and N Australian lows

July - Azores and Pacific high, Asian low

51
Q

Water vapour % at the poles

A

4% of troposphere

52
Q

Speeds associated with dust and sandstorms and examples

A

15 to 20kts

Harmattan and haboob, n Africa and can extend up to 15,000ft

53
Q

What layer effects radio waves

A

Ionosphere in the thermosphere

54
Q

How long until a taf is issued and is valid for

A

Issued every 3 to 6 hours

Valid for 9 to 36 hours

55
Q

Average depth of radiation fog

A

500 ft agl but can extend up to 1500

56
Q

Why is DALR greater than SALR

A

Release of latent heat with condensation, reduces the rate of cooling

57
Q

Examples of mountain wave

A

Pennies

Rockies

Andes

58
Q

Diameter of a TRS eye

A

20-50km

59
Q

Temp for the highest risk of icing in normal and cb

A

Normal, 0 to -10c

Cb, 0 to -20c

60
Q

Ground speed of a tornado

A

20 - 40kts

61
Q

Ta in warmer than isa

A

Ta will be more than indicate, safe/under read

62
Q

PL diameter

A

2-5mm

63
Q

Secondary depressions

A

Form within the circulation of a primary low

64
Q

Most effective use of imaging

A

Comparing visual with infrared

65
Q

Could tops

A

Measured by radar, satellite, visual or triangulation

66
Q

Dimensions of a thermal wind

A

200 miles wide, 2miles deep, 2000 miles long

67
Q

Water droplet diameter and velocity

A

0.02mm and 0.012 m/s

68
Q

Example of foehn wind

A

Alps

Chinook USA

69
Q

Temp to get carb ice

A

Up to + 25c

70
Q

Vertical visibility is measured in

A

Ft

71
Q

Amsl comparing QFF to QNH

A

Warmer than isa, qff will be lower than qnh

Colder than isa, qff will be higher than qnh

Bmsl they are swapped

72
Q

Wegener bergnson findeisen theory

A

Precipitation starts as ice crystals, grow through sublimation by SCWD

73
Q

Visibility in precipitation

A 
Mod ra 3-10km
\+ra can be below 1000m 
Mod SN 1000m
DZ less than 500m
\+SN below 50m
74
Q

Example of katabatic wind

A

Bora - Adriatic, 70 to 100kts

75
Q

Annual number of hurricanes occurring in n Atlantic, ne coast of Australia, s China sea, n India

A

N Atlantic - 7 to 9 (10 or less)

Ne coast of Australia- 9

S China sea - 25, 16

N India - 5 or 6

76
Q

Main ISA density altitudes

A

22,000 ft - 0.609 (halved)

40,000ft - 0.302 (quarter)

77
Q

Mist

A

1000 - 5000m

78
Q

What does U and D stand for in rvr

A

U - upward tendency

D - downward tendency

79
Q

Mamatus

A

Downward protruding

80
Q

Height of a Stevenson screen and what does it measure

A

4 ft / 1.2m

Temp and humidity

81
Q

Cold occlusion

A

Cold air behind the cold front is colder precipitation falls on both sides but mostly ahead

82
Q

Drizzle drop diameter and velocity

A

Less than 0.5mm 4 m/s

83
Q

How long do cold air pools last, width and height

A

Several days

300nm - 600nm wide

10000 to 30000ft deep

Serious unstable air

84
Q

Cloud base

A

Lowest level of cloud, measured by a ceilometer

85
Q

Continuous precipitation

A

60 mins or more

86
Q

The cause of thermal winds

A

Different air mass temps - jet streams

87
Q

Windshear classifications

A

Vertical - speed/direction change with altitude, kts/100ft

Horizontal- wind change on the horizontal plane, kts/1000ft

88
Q

When is there a 2nd vis reported

A

If a given area has 50% prevailing or below 1500m

89
Q

SG diameter

A

Less than 1mm

90
Q

En route reports

A

Volmet, metar for 10 airfields, wind true

Atis

Weather warnings - Sigmet/Airmet, produced by the meteorological watch offices

91
Q

Ta in colder than isa

A

Ta will be less than indicated, over read/ dangerous

92
Q

DALR and SALR lapse rate in ft

A

DALR - 3 degree/1000ft

SALR - 1.8 degree/1000ft

93
Q

Visibility in fog

A

Less than 1000m (999m)

94
Q

Coalescence theory

A

Precipitation forms in clouds at temps above freezing, water droplets grow through collision until they fall with gravity from cloud

95
Q

Speed of wind the tunnel of a tornado

A

100 - 200 kts

96
Q

How long does a tornado last for

A

30mins

97
Q

How far does weather extend behind the cold front surface

A

50 - 100nm

98
Q

RA diameter and velocity

A

0.5 - 5.5mm 9m/s

Met (11 decks)

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