Facts Flashcards
Speeds for a tropical depression, storm and cyclone
Depression - 20 to 33kts
Storm - rotating 34 to 63kts
Cyclone - above 64 kts
They all travel at 15 to 20 kts across the surface
Gale,storm and hurricane wind speeds
Gale - 34 to 47kts
Storm - 43 to 63kts
Hurricane +64kts
Calculating density altitude
Apply 120ft for every 1c isa dev
Absolute humidity
Amount of water vapour in a volume of air
G/m3
GR diameter
5-50mm, highest recorded is 1kg
Small hail is less than 5mm
Back bent occlusion
Extend from the centre of depression where the occlusion starts
Sea breeze speed and average height
10kts in mid lats
10-15 miles inland and up to 1000 ft amsl
Northerly winds from n Africa
Scirocco
Khamsin
Ghibli
Deflection of the surface wind and the % of the speed of the 3000ft winds
Over sea - 10* 70%
Land by day - 30* 50%
Land by night - 45* 25%
Temp where there is mostly ice particles
Below -40
Hight of the tropopause at the equator and poles and the associated temps
Poles = 26,000ft/8km/ -50c
Equator = 60,000ft/18km/-75c
Why is wind speed faster around a high
Centrifugal force acts with the PGF
Works against PGF in a low
Humidity mixing ratio
Amount of water vapour in a mass of dry air
G/kg
PGF + CF are equal and opposite
Geostrophic wind
What happens if rising cools without any condensation nuclei
The air is super saturated at a temp above 0c
SCWD are former below 0c
Height of the different satellites
Geostationary 35,786km , poor resolution, identify TRS
Polar orbiting 850km and orbit daily, high resolution
Routine reports
Metar
L/d forecast/trend
Speci - change in operational significance
All issued by meteorological stations aerodrome based
Heights and lats of the jet streams
Sub trop - fl400, 30 - 40 n/s
Polar front - FL300, 50 - 60 n/s
Arctic - fl200, 70n
Equatorial/easterly - fl500, 10 -20 n
ISA temp lapse rate in m
0.65c/100m
Visibility in cloud
Low level 10 - 30m
Mid 20 - 1000m
High +1000m
Lines of equal wind speed
Isotachs
Rain ice
Clear ice
What is required to form a TRS and what is their track
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
Length of Turbulence after mountain wave and vertical wind speed
50 - 100nm downwind
Vertical windspeed 1000ft/min, waves 1500 ft deep
Higher the mountain, stronger the wave
Height of a transmissometer
7.5ft up
Finding qnh alt
Ta-(isa dev x 4 x FL/1000)
Examples of orographic depressions
Alps in n Italy in winter
Ts avoidance
20nm over 20,000ft
10nm If below
What measures ELR
Radiosonde
What is classed as a gust
Sudden increase in windspeed of +10kts
Equipment to measure humidity
Psychrometer
Anemometer
Measures surface wind, 10m up
Type of cloud with people mountain wave
Cap,lenticular,rotor or roll cloud
Haze
Less than 5000m
Temp to form snow
+4 to -5c
How fast does the warm front travel at
Travels at 2/3 speed of the cold front, so it always catches up with the warm front and forms an occlusion
What % of USA hurricanes develop from easterly waves
80%
Most common type of inland fog
Radiation
Equipment to detect lightning
Stormscope, strikefinder
Finding true altitude
Qnh alt + (isa dev x 4 x FL/1000)
Average height of the spheres
Troposphere- 11km
Strato - 50km
Meso - 80km/ -90c
How long is rvr averaged for
1min for ATC and 10mins for metar/taf
Routine forecasts
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
How often does a rvr update
Every 60s
Cb calvus
Developing ts cloud
Intermittent precipitation
Continuous with breaks
Classification of cloud coverage
0 - SKC 1-2 FEW 3-4 SCT 5-7 BKN 8 - OVC
Temp range where the most SCWD are found
0 to -10c
Warm occlusion
Warm front is colder than air behind
Precipitation falls ahead of the occlusion
Dominant pressure systems
Jan - Siberian, Canadian highs, Icelandic and N Australian lows
July - Azores and Pacific high, Asian low
Water vapour % at the poles
4% of troposphere
Speeds associated with dust and sandstorms and examples
15 to 20kts
Harmattan and haboob, n Africa and can extend up to 15,000ft
What layer effects radio waves
Ionosphere in the thermosphere
How long until a taf is issued and is valid for
Issued every 3 to 6 hours
Valid for 9 to 36 hours
Average depth of radiation fog
500 ft agl but can extend up to 1500
Why is DALR greater than SALR
Release of latent heat with condensation, reduces the rate of cooling
Examples of mountain wave
Pennies
Rockies
Andes
Diameter of a TRS eye
20-50km
Temp for the highest risk of icing in normal and cb
Normal, 0 to -10c
Cb, 0 to -20c
Ground speed of a tornado
20 - 40kts
Ta in warmer than isa
Ta will be more than indicate, safe/under read
PL diameter
2-5mm
Secondary depressions
Form within the circulation of a primary low
Most effective use of imaging
Comparing visual with infrared
Could tops
Measured by radar, satellite, visual or triangulation
Dimensions of a thermal wind
200 miles wide, 2miles deep, 2000 miles long
Water droplet diameter and velocity
0.02mm and 0.012 m/s
Example of foehn wind
Alps
Chinook USA
Temp to get carb ice
Up to + 25c
Vertical visibility is measured in
Ft
Amsl comparing QFF to QNH
Warmer than isa, qff will be lower than qnh
Colder than isa, qff will be higher than qnh
Bmsl they are swapped
Wegener bergnson findeisen theory
Precipitation starts as ice crystals, grow through sublimation by SCWD
Visibility in precipitation
Mod ra 3-10km \+ra can be below 1000m Mod SN 1000m DZ less than 500m \+SN below 50m
Example of katabatic wind
Bora - Adriatic, 70 to 100kts
Annual number of hurricanes occurring in n Atlantic, ne coast of Australia, s China sea, n India
N Atlantic - 7 to 9 (10 or less)
Ne coast of Australia- 9
S China sea - 25, 16
N India - 5 or 6
Main ISA density altitudes
22,000 ft - 0.609 (halved)
40,000ft - 0.302 (quarter)
Mist
1000 - 5000m
What does U and D stand for in rvr
U - upward tendency
D - downward tendency
Mamatus
Downward protruding
Height of a Stevenson screen and what does it measure
4 ft / 1.2m
Temp and humidity
Cold occlusion
Cold air behind the cold front is colder precipitation falls on both sides but mostly ahead
Drizzle drop diameter and velocity
Less than 0.5mm 4 m/s
How long do cold air pools last, width and height
Several days
300nm - 600nm wide
10000 to 30000ft deep
Serious unstable air
Cloud base
Lowest level of cloud, measured by a ceilometer
Continuous precipitation
60 mins or more
The cause of thermal winds
Different air mass temps - jet streams
Windshear classifications
Vertical - speed/direction change with altitude, kts/100ft
Horizontal- wind change on the horizontal plane, kts/1000ft
When is there a 2nd vis reported
If a given area has 50% prevailing or below 1500m
SG diameter
Less than 1mm
En route reports
Volmet, metar for 10 airfields, wind true
Atis
Weather warnings - Sigmet/Airmet, produced by the meteorological watch offices
Ta in colder than isa
Ta will be less than indicated, over read/ dangerous
DALR and SALR lapse rate in ft
DALR - 3 degree/1000ft
SALR - 1.8 degree/1000ft
Visibility in fog
Less than 1000m (999m)
Coalescence theory
Precipitation forms in clouds at temps above freezing, water droplets grow through collision until they fall with gravity from cloud
Speed of wind the tunnel of a tornado
100 - 200 kts
How long does a tornado last for
30mins
How far does weather extend behind the cold front surface
50 - 100nm
RA diameter and velocity
0.5 - 5.5mm 9m/s
