Mod 1 - MET Flashcards
Importance of Met in Aviation
Safety, regularity and efficiency of international air navigation.
What affects does Weather have on Aviation?
Safety
Economy
Comfort.
Decode WMO
World Meterological Office
Decode WAFS
World Area Forecast System
Decode WAFC
World Area Forecast Centre
Decode RSMC
Regional Specialist Met Centre.
Decode MWO
Meteorological Watch Office
Decode VAAC
Volcanic Ash Advisory Centre
Decode TCAC
Tropical Cyclone Advisory Centre.
Decode SADIS
Satellite Distribution System.
List sources used to gather Met Data
Wx station (with/without) shelter screen Registering balloon Wx observation on buoy or ship AMDAR - Aircraft Monitoring Data Relay Met satellite
List reasons for ISA
Establish stds for calibration of instruments
Vertical separation between AC
Comparing power parameters of AC and engines
What is the composition of ISA?
Nitrogen - 78% Oxygen - 21% Argon - 0.9% CO2 - 0.03% Water - 0%
What is the structure of ISA?
Troposphere Tropopause Isotherm Lower Stratosphere Upper Stratosphere
What is the Barometric Lapse Rate in ISA?
30’ / 1hPa
What is the Air Density in ISA?
1.225kg/m3
What is the height and temperature of the Tropopause?
11km
-56.5°C
What is the temperature Gradient to the Tropopause?
-2K / 1000’
What is the temperature Gradient at Lower Stratosphere?
Isotherm
What is the temperature Gradient at Upper Stratosphere?
+0.3K / 1000’
What is the structure of the Atmosphere Beyond ISA?
Troposphere Stratosphere Mesosphere Ionosphere Exosphere
What may occur at the Ionosphere?
Radio blackouts and skip
What is the height of average Tropopause at the poles and equator?
Poles - 6-8km
Equator - 16-18km
Composition of ‘Real’ Atmosphere includes what?
Additional 4% water
List problems due to Fog in Aviation
Airport reduced capacity Airport closure Go around Diversions Delays due to holding Taxi orientation issues.
What equipment and methods are used to measure fog?
Transmissometer (RVR)
Human Observation
What requirements do AC and crew use to deal with fog?
AC equipment
AC technical status
Crew licence.
State the conditions required for Radiation Fog
Clear sky
Only over continent
Light wind <10kt
High humidity
What is the average thickness of Radiation Fog
<2m MIFG or BCFG
Max 100m - 200m
What time of day and season is Radiation Fog more prominent?
Build up after SS
Most dense after SR
Long lasting during winter months.
How is Radiation Fog dissipated?
Sun radiation
Following a wx change.
State the conditions required for Advection Fog
Moist and warm air
Cold surface
Wind / air stream.
What is the average thickness of Advection Fog?
500m - max 1000m
Widespread.
Describe Advection Fog and the seasons
Spring - Fog formed over sea due to warm continent and cold sea
Autumn - Fog formed over continent due to warm sea and cold continent.
How is Advection fog dissipated?
Change of wx situation
Change of wind direction.
List conditions for Mixing Fog
Moist and warm air mixing with moist and cold air.
What is the thickness of Mixing Fog?
100km + wide along wx fronts
Mixing Fog is more prominent during which season?
Winter
How is Mixing fog dissipated?
Change of wx situation.
What factors can influence Visibility?
Visual object
Observer
Time of day
Position of the sun
What is the importance of Visibility for VFR Pilots?
Flight planning and flight operation
Vis at departure and destination airport
Vis en-route.
What is the importance of Visibility for IFR pilots?
Fuel planning and flight operation
Departure and destination minimas
Alternate minima
What is the importance of Visibility for Controllers?
Operational category of the airport
Airport capacity.
Name the different Types of Visibility
Flight Ground in sight Slant RVR Vertical Ground.
Ground Visibility Decode
4000
9999
1300 0800SE
4000m
>= 10km
Prevailing vis 1300m, lowest vis 800m to the SE.
Vertical Visibility Decode
VV003
VV///
VV000
Sky obscured, Vert Vis 300’
Sky obscured, Vert Vis not available
Sky obscured, Vert Vis <100’.
RVR Decode R1000 RP2000 R26L/0900D R07R/0800V1400U
RVR 1000m
RVR >2000m
RVR Rwy 26L 900m decreasing
RVR Rwy 07R 800m variation 1400m upward tendency.
Decode FU
Smoke
Decode DU
Widespread dust
Decode SA
Sand
Decode VA
Volcanic ash
Decode HZ
Haze
Decode BR
Mist
Decode RA
Rain
Decode DZ
Drizzle
Decode SN
Snow
Decode FG
Fog
Decode MIFG
Shallow fog
Decode BLSN
Blowing snow
Decode DRSN
Drifting snow
How is wind measured?
Wind sock
Wind vane
Anemometer
Height - 10m above GRD.
What is Mesoscale Wind System Force?
Gradient force due to pressure difference.
Describe the Mesoscale Pressure Gradient Force
From H to L pressure
The closer the isobars, the greater the G
The stronger the wind
Wind equalises pressure very rapidly.
Describe Land / Sea Breeze
Sea breeze: Wind moving from cold water surface to warm continent. Present during day with calm fine wx.
Land breeze: wind moving from cold land to warmer sea. at night
List Land / Sea Breeze Hazards
Sea Breeze -
Wind shear, strong surface wind, possibly Advection Fog
Land Breeze -
Less intense than sea breeze.
Describe Mountain Down Slope / Valley Up Slope
Circulation of wind down up and through a valley.
Evident during sunny calm days.
List Mountain Down Slope / Valley Up Slope Flight Hazards
Mountain Down Slope - Fog or stratus
Valley Up Slope - Turbulence, wind shear, strong CWC.
List Foehn Wind Flight Hazards
Upwind Side - Low ceiling, poor vis, incessant rain, embd CB, ICE, TURB, GR
Downwind Side - 30 - 50kt winds, rotor clouds - heavy TURB, mountain waves - heavy TURB.
What are the Physical States of Water
Solid
Liquid
Gas / Vapour
Definition of Dewpoint
The temperature (to which air has to be cooled down) at which condensation occurs.
List the Changing States of Water
Liquid to Solid - Freeze Solid to Liquid - Melt Liquid to Gas - Evaporate Gas to Liquid - Condense Solid to Gas - Sublimate Gas to Solid - Resublimate.
What are the hazards from Water to Aviation?
Fog Cloud Hail Freezing rain Snow Aquaplaning.
How is Atmospheric Humidity measured?
Hair hygrometer
Psychrometer
Dew Point mirror.
Definition of Spread
The difference between temperature and dew point.
If moisture in the air and temperature is constant what happens to Dew Point Spread Relative Humidity Probability of Fog
Increase
Decrease
Increase
Increase.
How is Atmospheric Pressure measured?
Mercury Barometer
Aneroid Barometer.
What does Barometric Lapse Rate depend upon?
Altitude
Temperature
Humidity.
What are the Barometric Lapse Rates?
Up to 18,000’ - 30’ / 1hPa
18,000’ - 36,000’ - 60’ / 1hPa
36,000’ and above - 120’ / 1hPa.
How is Atmospheric Temperature measured?
Mercury Thermometer
Bimetallic Thermometer
Resistance Thermometer.
When is coldest time of day?
30 min after SR
When is the hottest time of day?
2 hrs after noon.
Coldest months of the Year
Northern Hemisphere
Dec - Jan
Warmest months of the Year
Northern Hemisphere
Jun - Aug.
What is Inversion?
Layer of atmosphere where temp increases with height.
List influences of Air Density on Aviation
Performance Thrust Lift Runway length required Climb rate Drag.
What is the relationship between Air Density, Pressure, Humidity and Temperature
Air Density rises with increasing pressure and decreasing temperature
Air Density decreases with decreasing pressure and increasing temperature
Air Density decreases with increasing humidity.
What is the Human Critical threshold?
20,000’ - 40,000’
List reasons for wrong Altimeter Indications
Mechanical - friction, calibration Dynamic - turbulent air, motion of AC Wrong subscale setting Air humidity Air temperature Air pressure.
Altitude Error due to Air Temperature
Hot to cold you’ll never get old!
Altitude Error due to Air Pressure
High to low look out below!
What is the Dry Adiabatic Lapse Rate?
Ascending; -3K/1000’
Descending; +3K/1000’
What sort or air would a Dry Adiabatic Process occur?
Unsaturated