Meteorology Flashcards
AS (Cloud)
Altostratus
ATIS
- Issue Times
- Heights
- Wind
- Visibility
- Cloud Type
- Issue Times: Irregularly, when conditions change
- Heights: feet AAL
- Wind: Degrees magnetic
- Visibility: 4 digits, in metres for less than 5000m, KM 5000m or more
- Cloud Type: Only if CB or TCU
VA
Volcanic ash
Describe Equatorial Air (Airmass)
Less warm and very moist
Describe the mature stage - Thunderstorms
Due vast amount of water and ice carried aloft, updraughts can no longer provide enough buoyancy and moisture descends, often at high rate. Downdraughts at front portion of the Cb while updraughts continue to function at the rear. Violent turbulence zone is produced between the up and down draughts. As downdraughts hit the surface, they spread out horizontally. Freezing level oscillates, lower in the forward half of the cloud where the downdraughts prevail and higher where the updraughts are found (usually the rear). Onset of downdraughts causes precipitation in the form of heavy showers of water and often more hail. Lasts approx. 15-20 mins.
AMD
Amended
What happens to pressure before, at and after the passage of a cold front?
- Before: Decrease
- At: Arrest of fall
- After: Increase
CAT
clear air turbulence
SA
Sand
GR
Hail (5mm or more)
GS
Small hail (smaller than 5mm)
Warm advection means:
Warm air moving toward colder regions
METAR/METAR AUTO/SPECI
- Issue Times
- Heights
- Area covered
- Wind
- Visibility
- Cloud Type
- Issue Times: METARs on the hour, every hour; AUTOs every half hour
- Heights: feet AAL
- Area: Within 8km of the aerodrome reference point. If term VC is used, it applies between 8 and 16km from aerodrome reference point
- Wind: Degrees True
- Visibility: 4 digits, in metres until 9999m, 2 digits in KM above 9999m (not at AA/WN/CH)
- Cloud Type: Only if CB or TCU
MI
Shallow
Types of thunderstorms
- Orographic Thunderstorms
- Heat type (thermal) thunderstorms
- Convergence Thunderstorms
- Nocturnal equatorial Thunderstorms
- Cold stream (or cold advection) Thunderstorms
- Frontal Thunderstorms
Drizzle
DZ
Drizzle
Hail
Freezing Rain
Difference between gusts and squalls
- Gusts: momentary increases in wind speed. Generally caused by turbulence.
- Squalls: rapid increases in wind speed lasting some minutes then dying away. Caused by weather systems.
What happens to precipitation before, at and after the passage of a warm front?
- Before: Light rain turning to persistent heavy rain
- At: Rain ceases but may change to drizzle
- After: occasional rain or drizzle
Widespread Fog
What happens to pressure before, at and after the passage of a warm front?
- Before: Decrease
- At: Arrest of fall
- After: Steady or slightly rise
Aquaplaning speed formula
Vp=9 x Square root of tyre pressure in psi
Dangers of icing
- Increase in Drag
- Increase in all-up-weight
- Distortion of Aerodynamic Shape
- Increase in Stall Speed
- Loss of thrust
- Pitot-Static Blockage
- Loss of Aerials
- Fuel tank vent icing
- Icing of moveable aircraft components
Severe Turbulence
9999
Visibility 10km or more
(blank space) (Wx symbol)
Moderate (when included before a weather phenomenon)
Terms on TAF:
- NSC
- BECMG
- TEMPO
- FM
- PROB
- NSC: Used when cloud is not forecast
- BECMG: Permanent change
- TEMPO: Temporary fluctuations lasting less than 1 hour
- FM: Self contained part of the forecast expected to occur rapidly
- PROB: Percentage indicating probability of weather phenomena
ABT
About
What is Virga?
What does it mean to a pilot?
- Precipitation that is evaporating before it hits the ground
- Usually occurs where the air below the cloud is very dry
- Virga associated with showers suggests strong downdrafts with possible moderate or greater turbulence
TL
till
FU
Smoke
HVY
Heavy
TAF
Aerodrome Forecast
AC (cloud)
Altocumulus
TAF/TREND
- Heights
- Area covered
- Wind
- Visibility
- Cloud Type
- Heights: feet AAL
- Area: Within 8km of aerodrome reference point
- Wind: Degrees True
- Visibility: 4 digits, in metres until 9999m, 2 digits in KM above 9999m (not at AA/WN/CH)
- Cloud Type: Only if CB or TCU
What is a microburst?
- A downdraft that may emerge from a cloud or no cloud as high as 15,000ft
- Wind intensifies for about 5 minutes after ground contact
- Can occur in families (more than one)
- Speed differences from 50-100kts
- Vertical speeds in excess of 3,000fpm
ATIS
Automatic terminal information service
Rain
Describe the Decaying (Dying) stage - Thunderstorms
Updraughts cease so general descending motion takes place. Turbulence and gusts decrease. Precipitation is common and will occur underneath the entire base of the cloud. Freezing level bulges down relative to outside the cloud.
Intertropical Convergence Zone
Describe Ac (airmass)
Arctic Continental - extremely dry and very cold
ST (cloud)
Stratus
METAR AUTO
Automatic aerodrome routine meteorological report
VC
Vicinity of the aerodrome
What happens to temperature before, at and after the passage of a warm front?
- Before: Steady or slight decrease due to precipitation
- At: Increase
- After: Light change
Describe Tm (airmass)
Tropical maritime - very warm and very moist
TIL
Until
Define jet stream
A strong narrow current of air, concentrated along a quasi-horizontal axis in the upper troposphere or in the stratosphere, characterised by strong vertical and horizontal wind shears featuring one or more wind maxima. Wind strength must be greater than 60 knots.
/// (METAR)
Cloud is detected (unable to determine TCU/CB)
NC
No change
Types of Airframe icing
- Clear ice (translucent or glaze ice)
- Rime ice (opaque ice)
- Hoar frost
- Freezing rain
Air masses have uniformity in: (horizontal plane)
- Temperature
- Moisture content
- Temperature lapse rate
FC
Funnel cloud
Pre-requisites for the formation of mountain waves (large scale interference):
- Mountain range of substantial dimension.
- Wind more or less at right angles to the range.
- Low level wind must be at least 15 knots and increase in strength with height.
- A generally unstable atmosphere at low levels with a stable layer at altitude, normally slightly above mountain crests.
- The air above this layer should be less stable or slightly unstable.
SIGMET Symbols
Severe sand or dust haze
Widespread sand storm or dust storm
WIndspread haze
Widespread mist
Widespread fog
Hail
Volcanic eruption
SC (cloud)
Stratocumulus
Widespread mist
What happens to precipitation before, at and after the passage of a cold front?
- Before: Not common
- At: Showers, possibly heavy, may include hail
- After: Showers may cease quickly, then isolated showers
What happens to visibility before, at and after the passage of a cold front?
- Before: Fair to good
- At: Very poor
- After: Very good but reduced in showers
G
Gusts
Rime Ice (Airframe Icing)
Occurs when small supercooled water droplets are disturbed and the amount of water flowing back is limited. Air pockets are trapped causing milky opaque appearance. Rime ice is rough and uneven in shape. Most likely to occur in stratiform cloud.
Describe Tc (airmass)
Tropical continental - very warm and very dry
Fohn wind requirements:
- Substantial mountain range;
- Wind blowing more or less at right angles to the mountain range;
- High moisture content of the approaching air
Convergence Line