Metrology Flashcards
ISA
International standard atmosphere
ISA temperature at sea level?
15oC
Atmosphere is higher where?
• Atmosphere extends furthest into the atmosphere at equator.
where does most of the worlds weather occur?
• Area where most weather occurs is called troposphere.
Broundery between Stratosphere and Troposhere?
• Broundery between Stratosphere and Troposhere is called tropopause.
• At sea level air density is …
normally 1,225 grams per cubic metre.
Ocean air is called..
• Air over the ocean is called maritime air
moisture content in ocean air?
• Air that passes over the ocean is going to be more moist.
Air is normally heated from what?
• The air surrounding the earth is mainly heated from below by the earths surface.
What is Terrestrial radiation
• Terrestrial radiation is the re-radiation of heat from the earth.
Advection?
• The transfer of heat by horizontal motion of an air mass is called advection.
Convection?
• The transfer of heat by vertical motion of an air mass is called convection.
Katabatic wind,
that flows down hills during the night as it cools
Anabatic wind,
that flows up hills during the day because of heating
Convert C to F
actual formula is multiply by 1.8, add 32
How fast does pressure drop?
Pressure drops about 1mb(HPa) per 30ft (at lower levels.
What causes the daily heating and cooling effects?
• The daily heating and cooling effects cause the semi-diurnal variation in pressure.
What do isobars do?
• Isobar, line on map joining places of equal sea level pressure.
What is the pressure gradient?
• The variation of pressure with horizontal distance is called the pressure gradient
What happens if you fly into an area of low pressure?
• If you fly into an area of low pressure and don t change altimeter setting. GRAD DECEND as that pressure height is now lower.
• ISA pressure at sea level
1013.2Hpa
• ISA density at sea level
1,225 grams per cubic metre.
• ISA temperature decrease,
2oC per 1000ft gained in lower levels
• Temperature lapse rate,
the actual rate of decrease of temperature with altitude.
• Above 36,000ft the ISA temperature
ceases to fall at -57oC.
What is Wind?
• Horizontal flow of air is called Wind.
Wind Direction, true or magnetic north?
• Wind direction is related to True North. oT
Runway headings, true or magnetic north?
• Runway headings are related to Magnetic headings. oM
• Wind direction that has changed in a clockwise direction is said to have..
Veered.
• Wind direction that has changed in a anti-clockwise direction is said to have…
backed
Pressure gradient force?
force that sets air parcel in motion from high pressure to low.
Coriolis force?
• Force that causes the curing direction of the wind is called the Coriolis force.
Coriolis winds directions?
• Coriolis winds caused by rotation of the earth, strongest towards the poles. (northern Hemisphere, goes to the right, southern to the left)
Geostrophic wind
• Geostrophic wind, wind that is created when the pressure gradient is balanced by Coriolis force so that the wind blows parallel to the isobars.
• Surface wind is measured at
10m
• Surface wind is decreased by
Friction
• The surface wind gradient will
back
• The backing of the surface wind is more pronounced over
land
• There is more vertical motion of air
at night
• Surface wind stronger during
the day
• Surface wind 330/20 at altitude example?
350/30
• Altitude wind 240/35, surface example?
220/20
• Variation of wind speed and direction is called
wind sheer
• The ability of aeroplane to climb is ……… when flying up a valley towards high ground in a strong headwind.
degraded
• Mountain waves present when
lentical waves are formed.
Effects of mountain waves can be felt up to
40nm downwind
4 types of cloud?
- Cirriform
- Cumuliform
- Stratiform
- Nimbus
• Cumuliform?
heaped or lumpy clouds.
• Stratiform?
extensive layer of clouds
• Cumulus?
Dense clouds resembling cauliflower
• Cumulonimbus?
heavy dense cloud with thunder and lightning.
Nimbus?
rain bearing.
humidity?
amount of water vapour parcel of air contains.
• Higher dewpoint temperature when
Humidity is higher
Air becomes saturated?
cloud cools when carrying max water.
Air expands as it
cools
• Adiabatic process,
heat is neither added nor subtracted.
• Enviromental lapse rate?
the rate of change of temperature in surrounding air that is not rising.
• The Level of cloud depends on
moisture content and dewpoint temperature
• Turbulance cloud?
cloud formed by mixing of air.
• Orographic cloud?
cloud formed by a mountain range causing uplift of air.
• Origraphic uplift of unstable air is more likely to cause formation
of cumuliform cloud. (stable air stratiform)
• Drizzle generally comes from
stratiform
Virga?
• Rain that falls but evaporates before it hits the ground.
Lenticular cloud?
• Cloud associated with standing mountain waves.
Conditions required for a thunderstorm?
- Instability
- Moisture
- Trigger action
Three stages of thunderstorm cycle?
- Cumulus
- Mature
- Dissipating
Three types of trigger action?
- Front forcing air aloft
- Strong heating
- Mountain forcing air up
Cumulas stage?
• The early Cumulus Stage, strong warm updrafts 1-2nm miles wide with no downdrafts (temp higher then outside).
Start of Mature stage?
• Lightning signify start of mature stage.
Mature stage?
• Mature stage contains updrafts and downdrafts (downdrafts and cool)
Anvil?
• Top of the cloud that spreads out is called an Anvil.
hazards caused by T’storm?
- Windshear
- Turbulence
- Icing
- Radio Interference
T’stoms can effect aircrfat up to …. nm
10nm
Subsidence?
slow sinking of an upper air mass.
What causes the slow rising of a large air mass?
• The slow rising of a large air mass is associated with convergence at the earth’s surface.
• Convergence is associated with a ……. pressure syestem
low
• Divergence is at the earth’s surface is associated with ……. pressure syestem
high
• Subsiding air becomes …………
• Subsiding air becomes warmer drier and more stable (subsidence is associated with stability)
Convergence is ……
instability
• Low pressure system
instability
• Warm front,
warm air displacing cool air
• Cloud base …….. are warm front approaches.
lowers
general cloud type associated with warm front.
stratiform
slope of a typical warm front?
1/150
cirrus clouds 200nm ahead of the surface front indicate?
warm front approaches
Rain fall associated with a warm front can fall ……..
up to several hundred miles ahead of the surface front.
what is a cold front?
• Cold air replacing warm air at the surface.
Cold front clouds?
cumuliform. (form suddenly, showers, Veer)
Cold front passes
temperature and dew point fall.
• Cold and warm fronts, wind will
veer
• Occluded front?
when cold front overtakes a warm front.
Ice forming and you can ‘t decend further? Actions?
Turn around
Northern Hemisphere, wind flow around high pressure?
• Northern hemisphere, wind flows antclockwise around low pressure. (starboard (right) drift).
rising air is associated with
low pressure
trough?
V-shaped extension of low pressure
what front moves faster?
Cold
high or low for good weather?
High, calmer weather
• Subsiding air associated with
highs (good weather)
Anti-cyclone
High pressure syestem
ridge
u-shaped extension isobars
Col
almost constant pressure between two highs and two lows.
Airframe ice?
ice that forms on the wings, prop etc.
carburettor ice?
ice can form when the outside temp is as high as 15oC.
Clear ice?
• Clear ice is most dangerous type of airframe ice
Large supercooled droplets cause
clear ice
Small supuecooled droplets cause
rime ice
Requirement for radiation fog?
- Cloudless night
- Light winds
- Moist air
• 1km = in mist
fog, 1.5km mist (Visibility)
What is Advection fog?
• Advection fog, formed if warm moist air flows over a cold surface, it will cool. It has to then cool to its dew point to form fog.
What is Radiation fog?
terrestrial radiation causes the surface to cool at night. This will cool the air in contact with it and form fog.
What is frontal fog?
fog formed by the interaction of two air masses.
Inversion
when temperature increases with height
When is a inversion most likely to occur?
• More likely an inversion will occur at dawn
how can winds cause stratus clouds?
• Winds can cause fog to lift and form stratus.
• As the land heats up during the day the
sea fog may drift over the land.
• When flying beneath an inversion, visibility is going to be
poor because of mist, fog smog.
• Aerodrome forecast, TAF?
TAF forecast of expected weather at aerodrome.
METAR?
routine aerodrome report
SIGMET
significant weather that may effect a flight.
Weather phenom that may effect the safty of a flight.
- Active thunderstorms
- Tropical revolving storms.
- Heavy hail
- Mountain waves
AIRMET
info available by phone or fax and aerodrome briefing offices.
VOLMET
service that broadcast metrological reports continuously from aerodromes.
TAF cycle in hrs?
• TAF normally issued for aerodrome on 9 hour cycle.
• Report of weather at a specific aerodrome is called a ?
METAR
NOSIG
no expected change for two hours.
• Cloud base given as height ….
above aerodrome
9999Vis
Vis greater then 10km
CAVOK
Visibility is more than 10 km (9999) No clouds below 5000 feet. NSW
TEMPO
temporary weather change occurring, would not be accurate to put out a TAF.
PROB20
Possibility 20%
RVR
runway visual range
TCU
cloud is towering cluminimbus
EMBD
thunderstorms are in other clouds, difficult to see
BECMG
weather will change in forecast period
• TAF 1220 means
1200 to 2000 hrs
• METAR 1220 means
1220 hours
+ =
- =
heavy and light
RADZ
rain and drizzle
+SHRAGR
heavy rain and showers with hail
NSW
no significant weather
• Temp 03/M01
temp 3oC and dewpoint -1.
SAUK
METAR
FCUK
TAF
TAF AMD
amended aerodrome forecast.
BR
mist
FZ
freezing
LYR
layer
Radiation fog is usually associated with:
anticyclonic conditions
Whilst reading a UK Metform 215 (F215), you see a weather phenomena marked as OCNL. What does this mean?
It is occasional
Cirrus cloud, giving way to Altostratus cloud, then Nimbostratus with steady rain is associated with:
a warm front.
If the environmental lapse rate is 1.4 degrees Celsius per 1000 ft, the air mass is said to be:
stable.
An elongated area of high pressure is commonly known as a:
trough
A heavy shower would be reported in a METAR as:
+SH
A heavy shower would be reported in a METAR as:
10,000ft amsl
In a TAF or METAR, a wind blowing from the west, at a strength of 20 knots would normally be written as:
27020
Why is the saturated adiabatic lapse rate less than the dry adiabatic lapse rate?
Because latent heat is released as water vapour condenses
At which of the following temperature and humidity levels is carburettor icing most likely to occur?
Highest humidity lowest temperature
Which of the following lists correctly describes the layers of the atmosphere, starting with the one closest to the earth?
Troposphere, Stratosphere, Mesosphere, Thermosphere
Fairford is reporting the following METAR: EGVA 070755Z AUTO 06003KT 9999 OVC034 12/11. What is meant by AUTO?
The entire METAR has been automatically generated
You are reviewing a UK Metform 215 (F215), and read the following text: MTW MAX VSP 700 FPM AT 080. What does this mean?
Mountain wave activity is present, with a maximum vertical speed of 700 ft / min
What visibility and cloud conditions are being experienced at Cork from this latest METAR? EICK 261530Z 09014KT 9999 FEW006 BKN034 15/14 Q1015 TEMPO 5000
1-2 oktas cloud at 600 ft, broken cloud at 3400 ft and temporary periods of reduced visibility
How are cumulus clouds with marked vertical development identified in a METAR?
TCU
Katabatic winds are typically _______ anabatic winds. What are the missing words?
stronger
The Fohn wind effect describes the effects of moist air rising over a mountain. On the other side of the mountain, the airflow tends to be:
drier and warmer
Precipitation on other side of mountain removes moisture
Form F215:
UK low-level weather chart providing a graphical display of areas of different weather plus text relating to surface visibility, weather and cloud up to FL100, updated four times a day.
Form F214:
UK spot wind chart providing wind speed and direction and temperature for standard levels up to FL240, updated four times a day.
Form 414:
European spot-wind chart providing wind speed and direction and temperature for standard levels up to FL240, updated twice a day.
Form F415:
European low-level weather chart providing a graphical display of areas of different weather plus text relating to surface visibility, weather and cloud up to FL100, updated four times a day.
As the warm front approaches at the surface, the air pressure will:
steadily fall
An environmental lapse rate of 1.8 degrees Celsius per 1000 ft indicates that the air mass is:
conditionally unstable
Tropical maritime air masses are commonly:
stable, warm and moist
London City is reporting the following METAR: EGLC 070750Z AUTO 03002KT 4600NDV BR OVC010/// 11/10 Q1023. What is meant by 4600NDV?
No directional variation
On a weather chart, what abbreviation is used to describe conditions likely to be encountered ‘At Sea’?
SEA
A warm moist airflow from the sea moving over a cold land mass can lead to:
advection fog
The dry adiabatic lapse rate is usually taken to be:
3.0 degrees Celsius for every 1000 ft
Which of the following weather conditions would NOT be reported as CAVOK?
Visibility 15km, broken cloud at 12000 ft including cumulonimbus at 18000ft
The atmospheric pressure at any given place is constantly varying.
weather systems and the daily heating effect of the sun
What are the hazards to aviators caused by thunderstorms?
A Loss of control due to severe windshear
B Damage from hail and lightning strikes, interference with radio equipment
C Structural damage in severe turbulence
CAVOK term
(aviation) Ceiling and Visibility are OK; specifically, (1) there are no clouds below 5000 feet above aerodrome level (AAL) or minimum sector altitude (whichever is higher) and no cumulonimbus or towering cumulus; (2) visibility is at least 10 kilometres (6 statute miles) or more; and (3) no current or forecast significant weather such as precipitation, thunderstorms, shallow fog or low drifting snow.
A 24h TAF will have usually been issued ______ in advance of the start of the TAF. What are the missing words?
1 hour
With respect to Significant Weather information, what is meant by the abbreviation ‘COT’?
coast
What sort of weather would you associate a tropical continental air mass with?
Hot and dry conditions with the possibility of haze in summer
What visibility and cloud conditions are being experienced at Cork from this latest METAR? EICK 261530Z 09014KT 9999 FEW006 BKN034 15/14 Q1015 TEMPO 5000
1-2 oktas cloud at 600 ft, broken cloud at 3400 ft and temporary periods of reduced visibility
Standard increases in temperature with altitude
2oC 1000ft
veering
clockwise
backing
anticlockwise
divergence
high
Convergence
low
Polar maritime?
cold, moist, unstable
polar continental
cold, dry
Tropical maritime
warm, moist, stable
tropical continental
warm, dry
Warm front from the ground?
high cirrus clouds
lower base of cirro, alto and nimbo stratus
rain may fall and virga may occur
Cold front
Cooler air mass undercutting a mass of warm air, which is displaced at the surface.
Hoar ice formation
surface temperature reaches freezing point before dew begins to form on it.
rime ice formation
Rime is a rough white ice deposit which forms on vertical surfaces exposed to the wind. It is formed by supercooled water droplets of fog freezing on contact with a surface it drifts past.
At sea level on the windward side of the mountain, the air has a temperature of +19 and dew point +13 degrees Celsius. Due to rainfall, the dew point becomes +11.5 degrees Celsius on the lee side of the mountain. Approximately what would you expect the cloud base to be on the windward side?
2000ft
The ratio of water vapour actually in a parcel of air, to what that parcel of air can hold when it is saturated is known as the:
relative humidity
What sort of weather conditions is an arctic maritime air mass associated with?
Cold, occasional precipitation with dry and clear conditions especially in winter
The stage in the life cycle of a thunderstorm, where mainly downdrafts are experienced is termed the:
dissipating stage
In the northern hemisphere, when wind comes into contact with the surface of the earth, friction causes it to:
back in direction and slow down
Immediately after the passing of the warm front, the temperature will:
rise
As air rises and cools, its relative humidity will:
A increase
What sort of weather are tropical maritime air masses usually associated with in winter?
cloud and rain
The presence of an ‘anvil’ topped cumulonimbus cloud ahead indicates the presence of:
an area of strong up and downdrafts, which may be part of a thunderstorm.
