MET Flashcards
FBL
Light - (METAR) (stands for Feeble)
HVY
Heavy + (METAR)
VC
Vicinity
MI
Shallow
BC
Patches
PR
Partial
DR
Drifting
BL
Blowing
SH
Showers
TS
Thunderstorms
• Local storm produced by one or several CBs
• Can exist together with non-convective clouds (embedded)
FZ
Freezing
DZ
Drizzle
RA
Rain
SN
Snow
SG
Snow Grains
PL
Ice Pellets
GR
Hail
GS
Small hail or snow pellets
BR
Mist
FG
Fog
FU
Smoke
VA
Volcanic ash
DU
Dust
SA
Sand
HZ
Haze
Small dust particles
SQ
Squall
FC
Funnel cloud
PO
Dust/Sand whirls
DS
Dust storm
SS
Sandstorm
Low clouds
0-6500ft
Stratus, Stratocumulus, Cumulus
Middle clouds
6500-20 000ft
Altostratus, Altocumulus, Nimbostratus
High clouds
Over 20 000ft
Cirrus, Cirrostratus, Cirrocumulus
TC or TCU
Towering Cumulus
CB
Cumulonimbus
• Strong possibility for icing
Tropopause height?
7-18km (22 000- 60 000ft)
depending on season and latitude
Dew point
100% Relative humidity
(Full saturation)
Strati form clouds
• Continuous precipitation
• Drizzle, rain, snow
• Steady intensity - light to moderate
• Smaller sized particles
Convective clouds
• Precipitation with larger sized particles
• Intermittent duration
• Varying intensity - moderate to heavy
• Showers rain/snow, hail
Virga clouds
Precipitation evaporating before reaching the ground
Cloud Base
The lowest height of the visible portion of the cloud
Cloud Ceiling
The height above the ground or water of the base of the lowest layer of cloud below 20 000ft covering more than half (5 octas or more) of the sky
FEW
Few (1 to 2 octas)
SCT
Scattered (3 to 4 octas)
BKN
Broken (5 to 7 octas)
OVC
Overcast (8 octas)
VV
Vertical visibility (indefinite ceiling)
No base layer can be measured by electronic equipment
CAVOK
Ceiling and visibility OK
• Visibility 10km or more
• No CB or TC
• No cloud below 5000ft or Minimum Sector Altitude (MSA) (whichever is greater)
• No significant weather at or in the vicinity of the aerodrome (No SIGMET)
NSC
No significant clouds
NCD
No clouds detected
RE
Recent
Front
Boundary between two air masses with different characteristics
Frontline
Where boundary between two air masses passes over ground (like you see on weather maps)
Warm front
• Advancing warm air mass will slide on top of a colder denser air mass
• The inclination from the frontal surface is very low, extending 300-500NM from the surface to the tropopause
• Gradually lowering cloud base
• Continuous precipitation, risk of fog
• After front passage - gradual break up
• Layered clouds and reduced visibility
• Clouds associated: CI, CS, AS, NS, SC and ST
Cold front
• Cold air pushes under warm air
• Steep frontal surface
• Rapid lifting of warm air gives forced convection and showers
• Fast ground movement - passes quicker, gives drop in temperature and change in wind direction
• Fairly high cloud base and good visibility when no precipitation
Windshear
• Difference in wind speed and direction over a relatively short distance
• A microscale meteorological phenomenon occurring over a very small distance
• Especially dangerous close to the ground or terrain with limited manoeuvring speed and area
• An aircraft in turbulent conditions may experience extremely hazardous airspeed fluctuations, can displace an aircraft from it’s flight path
The mature stage of CB
• Maximum vertical extent
• Precipitation reaches ground
• Downdrafts occur below the cloud base
• Strong upward and downward motion in different parts of the cloud
• Strong and gusty winds, lightning, heavy rain/hail and even funnel clouds can occur
Fog and Mist
• Clouds touching the ground
• The cooling producing fog usually arises from radiation, advection or mixing
• Droplets form when air is cooled to dewpoint and becomes saturated
• Droplets of water are suspended into the air by upward motion
Fog visibility?
Less than 1000m
Mist visibility?
Between 1000-5000m
NOSIG
No Significant Change
METAR
Meteorological Aviation Routine Weather Report
• Weather in vicinity of aerodrome (16km radius)
• At half-hourly intervals, min 20 and 50
• If significant changes occur between two reports, a SPECI is created
Wind calm
00000KT
Strong wind
Ett P används
Ex: 170P99KT
WS
Windshear
TAF
Terminal Aerodrome Forecast
• Period of validity: 9, 24 or 30h
• Amended forecast is issued if significant changes to expected conditions - TAF AMD
PROB
Probability, followed by 30 or 40 to indicate percentage of risk of the specified weather
SIGMET
Significant Meteorological Information
• En-route weather
• Valid no longer than 4h
• Refers to FIRs
CAT
Clear Air Turbulence
MTW VSP 600FPM
Mountain waves vertical speed 600 feet per minute
RVR
Runway Visual Range
• Reported if visibility or RVR is less than 1500m
• Normally measured by transmissometer or forward scatter meter but can be measured by human observer
• Generally measured at three parts of the runway: touchdown zone, mid point and stop end
Ceilometer
Measures cloud ceiling or base
(Before the runway)
R01R/P2000
RVR Runway 01R more than 2000m
Measure humidity
Hygrometer
Measure pressure
Barometer
Occluded front
Cold front catching up to a warm front
How are wind patterns in the northern hemisphere around a low pressure?
Counter-clockwise along the isobars
Trough
Elongated part of the low pressure area
Ridge
Elongated part of the high pressure area
Col
A region of lower air pressure between two high pressure areas
Cloud most likely to produce freezing rain
Nimbostratus
Adiabatic cooling or heating
Temp change of air due to compression or expansion with no external heat transfer
Latent heat
Heat released or absorbed during the change of state of e.g. water
ISA - International Standard Atmosphere
MSL pressure: 1013.25 hPa
Base temp: 15 celsius
Density: 1.225 kg/m^3
No water vapour
