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32 Cards in this Set
- Front
- Back
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Rime Ice |
Small supercooled water droplets. Freeze quickly, in temps - 10 to - 30. Found in thin cloud above freezing level. |
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Clear Ice |
Larger supercooled water drops, freezes slowly, warmer, spreads out. Temps 0 to -15 Found in thick cloud JUST above frz level |
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Waterspout |
Reaches down from cumulonimbus cloud to suck water up. Can be dangerous to light aircraft. |
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Sea breeze |
Blows from the sea. Land heats up faster than sea, pressure drops more over land and air moves toward low pressure. Strongest on a sunny day mid afternoon. |
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Convergence Thunderstorms |
Triggered along a well formed trough of low pressure. Wind veers accorss isobars toward lowest pressure. Air along trough line folds back on itself. This convergence forces air to rise at the surface. Can form for many hundreds of miles. |
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Hail |
Hail is most commonly experienced between 10,000 and 20,000 feet. Mid levels |
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Mountain waves |
• Wind speed of 25kts and at right angles to the tops of mountains. • Wind speed increasing with height • Lwr level - unstable • Mid level - stable • Top level - less stable • Allow at least 1000ft clearance height over mntns. Approach at 45° |
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Formation of Cyclone |
• Forms from small/intense low pressure system over warm tropical ocean • Forms between 5°S and 15°S • A warm ocean surface, Nov - Apr (southern hemisphere) |
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Hoar Frost |
A cold soaked aircraft on descent encounters a warmer layer of humid air, water vapour in the air skips the liquid state and turn directly into ice on the ac's cold surface. |
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Hoar Frost |
A cold soaked aircraft on descent encounters a warmer layer of humid air, water vapour in the air skips the liquid state and turn directly into ice on the ac's cold surface. |
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Dust Storms |
Extremely restrict Viz over a widespread area with heights over 10 thousand feet. |
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Clouds associated with Rime Ice |
• Altocumulus - light rime ice • Altostratus - Moderate rime ice • Nimbostratus - Moderate rime • Stratocumulus - If flight above frz lvl occasional rime ice |
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Clouds associated with Clear Ice |
Altostratus - possible in lower levels of the cloud Nimbostratus - Probable in low lvls of cloud when turb present Cumulonimbus - Highly likely |
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SPECI |
When conditions at an Aerodrome fluctuate about or are below certain specified criteria, the aerodrome changes from a METAR to SPECI. The SPECI is likely to contain info of greater op sig |
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Surface air temp is measured |
In the shade at heights between 1.25m and 2m |
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NOSIG |
No significant change is expected in the weather reported in the METAR for the duration of the TAF period |
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RWY VISUAL RANGE (D, U, N, P, M) |
D = downward trend U = Upward trend N = Nil trend detected P = The value is either 2000m or more than max detectable dist M = Value detected is either less than 50 or less than detectable |
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Automatic meteorological recording equipment |
When detectors cant detect all types of weather slashes will replace them // • Viz //// • Weather // • Cloud ////// |
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GPWT |
•Valid section = means from that date and time forward •GPWT issued every 6 hours •Low level charts valid for 3 hours |
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CAVOK |
REPORTS FROM STAFFED LOCATIONS ONLY • Viz 10km or more • No cloud below 5000ft • No cb at any height • No signigicant weather |
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Gradient and geostropic wind height |
Occur above about 3000 ft |
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Surface wind direction and strength land and sea |
Surface speed usually measured at a height of about 10m. • Land - surface wind speed drops by 2 thirds, veers to the right by 30 degrees • Sea - surface wind speed drops by 1 third, veers by 10 degrees |
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Visibility in Fog |
Viz in fog must be less than 1000m, if it's 1000m or greater it will be clasified as mist. |
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Rotors |
• Air beneath the crests of air waves curls to form rotors • Worst turbulence is found closest to rotors • Cloud in rotors or waves not always present • Lenticular cloud forms above rotors in humid air • Roll cloud can also form in the rotor zone in humid air |
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Squall and gust definition |
• Squall - wind speed of 16 - 22kt or more sustained for more than 1 minute. • Gust - sudden change of less magnitude and duration |
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South east trades |
• Westerly winds blow across the pacific and bring warm water and good rains to east coast of Aus. • Cold water wells up along the coast of sth America |
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El niño |
• Causes warm surface water to move eastward and east coast of Aus to experience lower than usual atmospheric pressure. This weakens pressure dif across the ocean and the trade winds falter or reverse. • Basically a reverse of normal conditions |
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Monsoon |
• Season wind from temp difference over land and sea • Stronger effect in northern hemisphere due to more land mass |
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Migration |
The equatorial trough (belt of low pressure, also known as the ITCZ) moves further north of the equator in the northern hemisphere summer because of the larger land mass. When the sun is directed more over the land it creates a low pressure system due to rising air (convection) |
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DIURNAL VARIATION |
Diurnal means follows a regular temp pattern. Hottest in mid afternoon, coldest at dawn. Variations to this can be.. • Cold fronts • Coastal areas due to ocean resistance to temp change • Windy areas - mixes air masses • Cloud cover - keeps warmer at night, blocks warmth during day • Places or high relative humidity has similar effect to cloud cover • Pressure systems |
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Cyclonic flow |
Cyclonic flow means with the direction of earths rotation. •Cyclonic direction Nth hem - anti clockwise •Cyclonic direction Sth hem - clockwise • A low pressure sys is cyclonic in the sth or nth hemisphere • A high pressure sys is anti-cyclonic in either hemisphere also |
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3 types of Inversions |
• Subsidence inversion - high pressure system • Radiation Inversion - like fog formation • Frontal inversion - warm air forced up and over cold air |
