término  |
definición |
What are the key ISA reference values worth remembering? empezar lección
|
|
Sea level: 1013.25 hPa and +15°C; tropospheric lapse rate about 2°C/1,000 ft; ISA tropopause about FL360 at −56.5°C.
|
|
|
How do pressure, temperature and humidity affect air density? empezar lección
|
|
Density decreases with lower pressure, higher temperature and higher humidity.
|
|
|
What happens to true altitude when flying from high pressure to low pressure without correcting the altimeter? empezar lección
|
|
True altitude becomes lower than indicated — “high to low, look out below”.
|
|
|
What happens to true altitude in air colder than ISA? empezar lección
|
|
True altitude is lower than indicated; the effect becomes more important with increasing height above the altimeter-setting source.
|
|
|
Why is cold-temperature altimetry particularly important on instrument procedures? empezar lección
|
|
The aircraft may be significantly lower than indicated relative to terrain and obstacles.
|
|
|
What does a small temperature–dew-point spread tell you operationally? empezar lección
|
|
Air is close to saturation, so cloud or fog becomes increasingly likely if further cooling occurs.
|
|
|
What determines atmospheric stability? empezar lección
|
|
How the environmental temperature lapse rate compares with the temperature change of a vertically displaced air parcel.
|
|
|
What weather is generally associated with stable versus unstable air? empezar lección
|
|
Stable: layered cloud, fog, poor visibility and smoother air; unstable: convection, cumulus/CB, showers and turbulence.
|
|
|
What is a temperature inversion and why is it operationally relevant? empezar lección
|
|
Temperature increases with height; the layer is strongly stable and can trap moisture, haze and pollutants beneath it.
|
|
|
Why does rising unsaturated air cool? empezar lección
|
|
Pressure decreases with height, so the parcel expands and cools adiabatically.
|
|
|
Why does saturated rising air cool more slowly than unsaturated air? empezar lección
|
|
Condensation releases latent heat.
|
|
|
What mechanisms commonly force air to rise? empezar lección
|
|
Convection, convergence, frontal lifting and orographic lifting.
|
|
|
What is the basic mechanism of cloud formation? empezar lección
|
|
Air cools to saturation and water vapour condenses or deposits on condensation nuclei.
|
|
|
How do radiation fog and advection fog differ? empezar lección
|
|
Radiation fog forms when the ground cools moist air near the surface; advection fog forms when moist air moves over a colder surface.
|
|
|
What conditions favour radiation fog? empezar lección
|
|
Clear or partly clear sky, moist near-surface air and light wind allowing strong nocturnal cooling.
|
|
|
Why can too much wind prevent radiation fog? empezar lección
|
|
Mixing prevents a shallow surface layer from cooling sufficiently to saturation.
|
|
|
How do a typical warm front and cold front differ operationally? empezar lección
|
|
Warm fronts usually produce widespread layered cloud and prolonged precipitation; cold fronts more often produce stronger lift, showers, convection and rapid weather changes.
|
|
|
What is an occluded front? empezar lección
|
|
A frontal system formed when a cold front catches a warm front and lifts the warm sector away from the surface.
|
|
|
How do pressure-gradient force, Coriolis force and friction determine wind near the surface? empezar lección
|
|
Pressure gradient drives air toward low pressure; Coriolis deflects it; surface friction slows the wind and makes it cross isobars toward lower pressure.
|
|
|
Why does wind usually increase and veer with height above the surface in the Northern Hemisphere? empezar lección
|
|
Friction decreases with height, strengthening the Coriolis balance and turning the wind toward the geostrophic direction.
|
|
|
What is operationally important about the tropopause? empezar lección
|
|
Jet streams, strong wind shear and CAT are frequently associated with it.
|
|
|
|
empezar lección
|
|
A narrow band of strong upper-level wind associated with strong horizontal temperature and pressure gradients.
|
|
|
Where is CAT most likely around a jet stream? empezar lección
|
|
In areas of strongest vertical and horizontal wind shear, often near the jet core and tropopause.
|
|
|
What is clear-air turbulence? empezar lección
|
|
Turbulence without significant visible cloud, commonly associated with strong wind shear near jet streams and upper-level frontal zones.
|
|
|
What conditions favour mountain waves? empezar lección
|
|
Stable air with strong wind crossing a mountain ridge approximately perpendicular to it.
|
|
|
What visual clues suggest mountain-wave activity? empezar lección
|
|
Lenticular clouds aloft and rotor clouds beneath the wave.
|
|
|
Where is the greatest turbulence threat in a mountain-wave system? empezar lección
|
|
In rotor and wave-breaking regions, especially on the lee side.
|
|
|
What three ingredients are required for thunderstorms? empezar lección
|
|
Moisture, atmospheric instability and a lifting mechanism.
|
|
|
What are the three thunderstorm stages and their dominant vertical motion? empezar lección
|
|
Developing: updrafts; mature: strong updrafts and downdrafts; dissipating: mainly downdrafts.
|
|
|
What are the major operational hazards of a CB? empezar lección
|
|
Severe turbulence, windshear/microbursts, hail, lightning, icing, heavy precipitation and possible rapid pressure/wind changes.
|
|
|
Why can a thunderstorm be hazardous even outside the visible cloud? empezar lección
|
|
Hail, turbulence, lightning and strong outflow/windshear can extend beyond the visible CB.
|
|
|
What is a microburst and why is it particularly dangerous near the ground? empezar lección
|
|
A concentrated downdraft with divergent outflow; during take-off or landing it can rapidly change headwind into downdraft and tailwind.
|
|
|
What is the typical wind sequence when penetrating a microburst on final? empezar lección
|
|
Increasing headwind, strong downdraft, then decreasing headwind or increasing tailwind.
|
|
|
|
empezar lección
|
|
A significant change in wind speed and/or direction over a short distance.
|
|
|
Where should low-level windshear be particularly expected? empezar lección
|
|
Near thunderstorms/outflows, fronts, strong inversions and terrain-induced flow.
|
|
|
Why can virga indicate a windshear or microburst threat? empezar lección
|
|
Evaporating precipitation cools the air, increasing its density and strengthening downdrafts.
|
|
|
What conditions are required for airframe icing? empezar lección
|
|
Supercooled liquid water must strike an aircraft surface whose temperature allows ice accretion.
|
|
|
What is the practical difference between rime, clear and mixed ice? empezar lección
|
|
Rime is rough/opaque from rapidly freezing small droplets; clear ice is denser and smoother from larger spreading droplets; mixed ice contains characteristics of both.
|
|
|
Why are supercooled large droplets (SLD) particularly hazardous? empezar lección
|
|
They can flow beyond normally protected leading-edge areas before freezing, producing rapid and extensive ice accretion.
|
|
|
Why is freezing rain a severe icing threat? empezar lección
|
|
It contains large supercooled droplets and can produce rapid clear-ice accretion over extensive surfaces.
|
|
|
What are the main aerodynamic effects of wing icing? empezar lección
|
|
Increased drag, reduced CLmax, lower critical AoA, higher stall speed and degraded controllability.
|
|
|
Why can the stall warning characteristics of an iced wing change? empezar lección
|
|
Ice alters the aerofoil and may cause separation and stall at a lower AoA than in the clean configuration.
|
|
|
Why is TAT higher than SAT/OAT at high speed? empezar lección
|
|
Air is heated by compression and conversion of kinetic energy as it is brought toward rest at the temperature probe.
|
|
|
What is the operational difference between BECMG, TEMPO and FM in a TAF? empezar lección
|
|
BECMG is a transition to new prevailing conditions; TEMPO describes temporary fluctuations; FM establishes new prevailing conditions from a specified time.
|
|
|
What does PROB30 or PROB40 communicate in a TAF? empezar lección
|
|
A 30% or 40% probability of the specified conditions occurring.
|
|
|
For operational planning, when is a BECMG deterioration normally considered to apply? empezar lección
|
|
From the beginning of the BECMG period.
|
|
|
For operational planning, when is a BECMG improvement normally considered to apply? empezar lección
|
|
From the end of the BECMG period.
|
|
|
Why is TEMPO different from BECMG operationally? empezar lección
|
|
TEMPO does not replace the prevailing forecast; it describes temporary conditions superimposed on it.
|
|
|
What is the practical distinction between SIGMET, AIRMET and GAMET? empezar lección
|
|
SIGMET warns of specified significant en-route hazards; AIRMET covers specified hazards mainly relevant to low-level flight; GAMET is a low-level area forecast.
|
|
|
|
empezar lección
|
|
A strategic picture of significant en-route weather such as CB, turbulence, icing, jet streams, tropopause and major hazardous phenomena.
|
|
|
What is the current vertical coverage of the new-generation WAFS SIGWX product? empezar lección
|
|
|
|
|
Why should METAR, TAF, SIGMET and SIGWX never be considered in isolation? empezar lección
|
|
They describe different locations, scales, time periods and hazards; the operational picture comes from combining them and continuously reassessing changes.
|
|
|
