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362 Cards in this Set
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Aviation definition of height
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* measured distance
> above the ground > (QFE) |
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Aviation definition of altitude
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* measured distance
> above ∆ local pressure setting (QNH) ∆ or altitude above MSL. |
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aviation definition of a flight level
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* measured pressure level
> above 29.92-in/1013-millibar datum (STD) |
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ISA is acronym for ?
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* International standard atmosphere
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ICAO ISA conditions at sea level
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Temp @ +15°C
Px @ 29.92 inHg / 1013 hp Density @ 1225 g/m3 |
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Air pressure is ....... .
Is influenced by ... and is proportional to ... . |
the weight of a column of air
gravity density |
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The air pressure (millibar) rate of change is more rapid .... .
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near the earth’s surface
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formula used to find the size of 1 millibar
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96 * ( K + actual T ) / Alt Px (hp)
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It is common to use ... for 1 millibar up to an altitude of approximately ... ft.
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30 ft
5000 |
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hp > inHg
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x 0.0295
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Pressure altitude
Is the .... , at which the .... represents that of the ... . |
ISA height above 29.92-in/1013 millibar pressure datum
pressure value experienced level under consideration |
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Converte Px altitude to actual altitude
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*calculate difference between the regional QNH and the 29.92-in/1013-millibar pressure datum
*Add to Px alt if QNH > STD datum *Sub from Px alt if QNH < STD datum |
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It is important to know what the actual height is for the purpose of ... .
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Ground clearance
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... is a commonly experienced Px altitude error.
It's the effect of ..... . |
*Barometric Px error
flying into an area with a different sea level Px |
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Barometric pressure error is especially important
when ... , which gives the effect of ..... . |
flying into an area with a lower actual sea level Px
overreading the aircraft’s altitude. |
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ISA Temp dev is the measurement of ... against the ... .
It's expressed as ... |
the actual temperature
ISA Temp for the corresponding altitude Deg. above or below ISA Temp |
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Calculate ISA Temp.
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(Number of Thousands * -2 ) + 15
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Density is .... or ....
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mass per unit volume
the degree of compactness of a substance |
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Density Altitude?
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The altitude in the Standard Atmosphere at which the prevailing density occurs
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Density Altitude is (~) .... corrected for ...
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Px altitude
non STD Temp |
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Air density is easily changed by .....
due to the influences of .... |
compression and expansion
1. Temp 2. Pressure 3. Humidit y |
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... is the main influence on air density
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Temperature
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Moist air is ... dense than dry air
because ...... . |
less
lighter water mol. replace some of the air’s heavier mol. |
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Density var. due to Temp vs. AC performance
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Warmer Temp
> Lower density > Dec Eng & Aerodynamik perf. |
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Density errors are commonly experienced?
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Altitude error
Air-speed error. |
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Air density variation vs. Altitude indication ?
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*Altimeter is a barometer
*Converts Px values to corresponding level *Calibrated to ISA *Any Temp dev from ISA > Chx in Density >> Altitude error |
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Air density variation vs. AS indication ?
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*ASI measures dynamic pressure
*Calibrated to ISA *Dyn. Px is prop. to Density *Any variation from ISA > incorrect indication |
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Static pressure?
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ambient pressure around an object
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Dynamic pressure is .....
caused by ... |
*the pressure of the air molecules impacting onto a surface
*relative movement of air and body |
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mains components that determine the amount of dynamic pressure
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1. speed of the body relative to the air
2. air density |
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Dynamic pressure = .....
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1⁄2R (rho) × V2 (TAS)
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Isobar?
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a line on
@ meteorologic chart joins places of equal sea level pressure. |
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Isotherm?
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a line
joining places of the same mean Temp. |
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Heat is ... that is measured in ... which represents the ...... .
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*a form of energy
*calories *energy required to raise the Temp of 1 g of water 1°C |
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The ...... provides the earth’s heat and light.
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sun
in the form of solar radiation |
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How the Atm is heated
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*1/2 of solar rad. reaches earth as short waves
*absorbed > heats the surface > Insolation *energy radiates back as long wave *heats the lower atm |
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Ways of transferring heat energy @ atmosphere?
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1. Radiation
2. Conduction 3. Convection |
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Cloud cover vs. surface heating
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*By day :
Stops incoming solar radiation > reduced lower Atm Temp *By night : traps heat energy @ lower Atm by reflecting back to surface >maintained higher Temp @ lower Atm |
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Specific heat capacity?
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The ability of a material
to hold thermal/heat energy. |
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Latent heat?
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The heat energy,
measured in calories, absorbed or released when water changes from one state to another. |
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When water changes to a higher energy state, i.e., from ice to liquid to vapor, it ... latent heat energy
(and vice versa) |
absorbs/uses
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Temperature?
a ... , which is represented as ... . |
measure of molecule agitation in a substance
the hotness of a body |
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Factors determining the Temp @ earth’s surface
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1. How much heat energy
in the form of short-wave energy reaches surface. a. Latitude > Max @ tropics : direct sun rays b. Season > Tilt : same effect as Chx of Lat. c. Time > Max @ 1500 hrs 2. energy absorption & retention capacity of surf. a. Absorption > type of surface : reflective quality b. Specific heat capacity of the surf. |
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Celsius scale (°C) ?
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It divides the Temp between boiling point and freezing point of water into 100 degrees.
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OAT ?
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Ambient outside air temperature.
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SAT?
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Ambient static air temperature
Commonly same as OAT |
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TAT is ... indicated on the ... ;
It is a product of ....... experienced on ... , |
*the total air temperature
*air temperature instrument *the SAT and the adiabatic compression (ram) rise in Temp *the temperature probe. |
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TAT is a ... than OAT whenever ... .
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higher temperature
there is an airflow into the temperature probe |
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Chx in air Temp vs. Aircraft FL
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Higher Temp than ISA
> less dense & lighter air > Altimeter under-reads |
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A Temp inversion occurs when ........ .
In other words, the air temperature ... |
*the air closest to the ground,
or even the ground it self, is cooler than the air above it *increases with height |
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When a Temp inversion occurs, it acts like ......... .
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a blanket , stopping vertical movement /currents
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Temperature inversion "layer"
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the height/altitude
Temp inc with hight changes to normal decrease with H |
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Isothermal layer
One where ..... through .... . |
the air remains at the same temperature
a vertical section of the atmosphere |
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The adiabatic process is one in which ........ ,
but .......... . |
*heat is neither added nor removed from a system
*any expansion or compression of its gases changes the Temp of the system with no overall loss or gain of energy. |
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A common adiabatic process for pilots?
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Expansion of a cooling parcel of air
when it rises in the atm. |
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ELR is short for .....
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Environmental lapse rate
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What is ELR?
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Rate of temperature change with height.
(of the general surrounding atmosphere) |
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ISA assumes an ELR of ... of height/altitude gained.
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2°C per 1000 ft
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DALR is short for
SALR is short for |
Dry adiabatic lapse rate
Saturated adiabatic lapse rate |
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What is DALR?
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The adiabatic Temp change
for unsaturated air as it rises. |
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DALR is a ... of height/altitude gained.
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drop of 3°C per 1000 ft
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What is SALR?
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The adiabatic Temp change
for saturated air as it rises. |
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SALR is a ... of height/altitude gained.
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drop of 1.5°C per 1000 ft
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When does SALR commence?
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*@ height where air’s Temp is reduced to its DP
*achieving 100% relative humidity *water condensing into cloud |
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SALR is .... than DALR because ......
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*lower
*latent heat is released *as the water vapor condenses into liquid |
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Humidity is ........ .
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the water vapor in the air
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Relative humidity is .......... .
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a measure of the amount of water vapor
present in a parcel of air compared with the maximum amount it can support at the same Temp. |
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Relative humidity is 100 percent when .... .
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the air is saturated
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The amount of water vapor a parcel of air can hold depends on .... .
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its temperature
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Humidity vs. Temp
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warm air > able to hold more water
cooler air > supports less water vapor. |
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The dewpoint is ...... .
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the temperature @ which a parcel of air
becomes saturated i.e when RH is 100% |
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Moisture content vs. DP
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proportional
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The properties for clout formation
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1. Moist ure present in t he air.
2. A lifting action a. Convection b. Turbulence c. Frontal d. Orographic 3. Adiabat ic cooling of t he rising air. |
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Process of cloud formation
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*parcel of air (+ water vapor) > lifted sufficiently
*cool adiabatically *cap to hold WV > dec *DP > Max RH > Saturated > no further WV support *more cooling > WV condenses > water droplets > clouds *if no support > fall as precep. |
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Height of cloud base
is determined by ......... . |
The difference between
the dew-point Temp and the ground temp |
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Cloud base formula
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= ( Surf. Temp - DP) / app lapse rate p1000 ft
x 1000 |
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Moisture content vs. Cloud base hight
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higher moisture
> higher DP >> less Surf. T / DP difference >>> lower cloud base |
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....... could limit the height of the cloud top
because .... . |
*surrounding Temp
becoming same/higher than Temp inside cloud *air becomes stable |
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Cumulus clouds flat bases due ...
Round and uneven tops because of ... |
*uniform dec in Temp of the DALR
*uneven ELR dec & various rising currents |
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4 main groups of clouds:
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1. Curriform > fibrous
2. Cumuliform > heaped 3. Stratiform > layered 4. Nimbus > rain-bearing |
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Cloud classification based on their base above MSL
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prefixed names added
1. Cirro, or high-level 2. Alto, or medium-level 3. Strato, for low-level |
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High-level clouds have cloud base of ...
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above 16,500
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Low level clouds have cloud base of ...
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Sea level to 6500
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Medium level clouds have cloud base of ...
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6 500 to 23 000 feet,
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Cumulus clouds @ morning
What to expect later?! |
CBs
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Formation of mountain (lenticular) clouds.
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*Orographic uplift > Airflow rise over mountains
*Cools adiabatically > up to DP Temp *Water vapor > condense out > form clouds, *If stable air above > lenticular clouds @ hillside *If unstable air above > cumulus or even CB |
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Rotor or roll clouds, particularly common with ... , also may form at ... as a result of ... .
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*lenticular cloud formation
*a low level downstream of the mountain *surface turbulence |
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Mist and fog are simply ....
that have ... that have the effect of ... . |
*parcels of low-level air in contact with the ground
*small suspended water droplets *reducing visibility |
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Different types of fog?
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1. Radiation fog
2. Advection fog, including sea fog 3. Frontal fog, including hill fog |
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Fog in general is caused by ... ,
due to ... between ..... or ..... , which as a result ..... |
*a condensation process
*a difference in temperature *the ground and the air next to it (rad/adv fog) *two interactive air masses (frontal fog) *reduces air Temp to DP |
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Radiation fog formation requirements :
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a. Cloudless night > surf. to lose heat by Rad.
b. Moist air > HR : so less cooling is req. to DP c. Light winds > 2 - 8 kts |
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Radiation fog occurs ... ,especially in ... .
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inland
valleys and low-lying areas |
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The term advection means ..... .
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heat transfer by the horizontal flow of air
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Advection fog and can occur ... (when/where)
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quite suddenly
day or night land or sea |
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Advection fog formation requirements :
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*Warm, moist air mass
flowing across (sig) colder surface, *Light to moderate winds > mixing of the lower levels |
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Sea smoke is ...
It's formed when ... . |
*Kind of Advection fog but in reverse
*very cold air > passes over a warmer sea |
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Frontal fog. Usually forms in ... as a ...
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*the cold air ahead of a warm occluded front
*prefrontal widespread fog |
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Dew is ... .
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a water cover on the earth’s surface
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Dew formation requirement
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1. Cloudless night > Rad. heat lose > condensation
2. Moist air > only slight cooling is req. to DP 3. Light winds > less than 2 kts |
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The conditions for dew to form are the same as for radiation fog except for ...
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the lower or nil wind.
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Frost is ... .
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a frozen water cover on the earth’s surface
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Frost is formed in the same manner as ...
except that the ... that causes .... |
*dew
*earth’s surface has a subzero temperature *the condensed WD to freeze out |
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What is Virga?
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rain that evaporates before it reaches the ground.
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Virga is a sign of a possible ... , which in turn is an indication of possible ... .
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temperature inversion
windshear |
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Thunderstorms are associated with ... clouds
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cumulonimbus
(CBs are the basis of TS) |
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conditions required for a CB cloud to develop
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1. High moisture content @ air.
2. Trigger lifting action (or catalyst) > rise air a. Convection b. Turbulence c. Frontal d. Orographic 3. Adiabatic cooling of the rising air. 4. Highly unstable atm. > once start rising : continue |
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For a CB to develop, effectively,
ELR must be ... than ... for over ... ft . |
greater
SALR 10,000 |
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Thunderstorms are examined in 2 stages
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CB development
the Life cycle |
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life cycle of the cumulonimbus cloud (associated with TS)
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1. Developing stage,
2. Mature stage, 3. Decaying stage. |
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Developing stage @ TS life cycle
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*updrafts move air aloft
*condensation takes place |
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Mature stage @ TS life cycle
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*water droplets falling through the cloud
*drawing air down with them > downdrafts @ middle *stil surrounded by updrafts |
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... phase of a CB cloud is the most hazardous stage of its thunderstorms.
It includes (6) |
*mature
a. Torrential rain b. Hail c. Severe turbulence d. Severe icing e. Windshear and microbursts f. Lightning |
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Decaying stage @ TS life cycle
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*End of continuous rain
*Sporadic showers / virga *Anvil shape @ higher levels |
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The danger associated with the Anvil @ TS
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marked downward vertical currents beneath it
> strong windshear |
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TS hazard to all AC types (7)
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1. Severe windshear
2. Severe turbulence 3. Severe icing (esp. clear) 4. Airframe structural damage from hail 5. Reduced visibility 6. Lightning strikes (dmg E sys) 7. Radio com. and nav. interference (static E) |
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TS hazards exist @ ...
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inside,
under, and for some distance around the assos. CB |
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TS CBS should be avoided by a minimum of ...
and in severe conditions by at least ... . |
10 nautical miles
20 nautical miles |
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Severe windshear (assos. w. TS) can cause :
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a. Handling problems
b. Flight path deviations, especially vertically c. Loss of airspeed d. Possible structural damage |
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Lightning is most likely to occur when ...
and within or close to ... . |
*the OAT is +10°C to –10°C
*a TS associated with a mature-stage CB cloud |
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Wind is ...... .
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the horizontal movement of air in the atmosphere
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Wing is driven initially by ... , and then it can be influenced further by a number of factors, including ... .
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*a difference in Px between 2 places
1. The earth’s rotation forces 2. Temp 3. Surface friction |
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Wind is expressed in terms of ... .
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direction and strength
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Wind direction
is the ... and is expressed in ..... expect for ..... |
*direction from which the wind blows
*degrees measured clockwise from "true north" *wind reported from Tower & *the upper winds for Airway planning >> which are Mag. N |
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Wind strength is measured and expressed in ...
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Kts
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Wind velocity relates to ... .
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the wind’s direction and strength
180/25 > from 180 @ 25kts |
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Veering wind?
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when it changes its direction in a CW direction
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Backing wind?
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when it changes its direction in an CCW direction
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buys ballot’s law?
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back to the wind @ NH,
the low Px ( Temp ) will be on your Left . |
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A pressure gradient force is ... generated by ..... .
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*a natural force
*a difference in Px across a horizontal distance |
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Pressure gradient force
acts at ... and is usually responsible for ..... . |
*right angles to the isobars
*starting the movement of a parcel of air from an area of high Px to an area of low Px |
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The coriolis (geostrophic) force is ... that acts on ...
that ... . |
*an apparent force
*a parcel of air *is moving over the rotating earth’s surface |
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The coriolis force is a product of ... .
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the earth’s rotational properties
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the coriolis effect?
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Deflects the simple H to L flow to R or L
deflects airflow to the R @ NH deflects airflow to the L @ SH |
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The geostrophic wind
is ... from a ... direction that is ......... and at a strength directly proportional to .... . |
*the balanced flow of air
*westerly *parallel to "straight" isobars >with a low-Px sys @ left *the spacing of the isobars |
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The geostrophic wind
is usually found at ... heights from approximately ... ft and above. |
low to medium
2000 |
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The geostrophic wind
is created when ........ . |
the two forces of
*Px gradient force and *coriolis (geostrophic) force are balanced |
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The gradient wind
is the ........ . |
resulting wind
blowing around the curved isobars common to circular low- or high-Px patterns |
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The gradient wind
is usually found at ... heights from approx ... ft and above. |
low to medium
2000 |
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Upper winds are determined by ...,
in which a ..... will cause a ... that will create ..... that is .... . |
*the thermal gradient
*difference in Temp btw 2 columns of air *Px difference @ height *a wind ( II to the isobars) @ alt. *different from SL winds |
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@ NH, the thermal gradient is generally ... , and therefore, the upper winds generally are ... in direction
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north-south
westerly |
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direction and speed of the upper wind is determined by ...... .
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vector sum of
*the isotherm thermal wind component *lower level geostrophic wind component |
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Regarding upper winds,
highest wind speed is where ..... . |
the thermal gradient is greatest
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Thermal winds are generated by ........ .
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a difference in Temp (thermal gradient)
between two columns of air over large areas at great upper heights. |
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The direction of a thermal wind is ... .
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parallel to the isotherms
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strength or speed of the thermal wind is directly proportional to ... .
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the temperature gradient
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Jetstreams are simply ..... .
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narrow bands
of high-speed upper thermal winds @ very high altitudes. |
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The wind speed must be ... for a wind to be classified as a jetstream.
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greater than 60 knots
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Jetstreams typically are
... long, ... wide, and ... deep, |
1500 nautical miles
200 nautical miles 12,000 ft |
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speed of a jetstream is directly proportional to ...
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the thermal gradient
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Jetstreams are found wherever & wherever ...... .
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the thermal gradient is high enough
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2 places @ which jetstreams exits in
..... where it's called ... and .... where it's called ... |
@ polar front ~ 60 degrees lat
> a polar front jetstream @ intertropical front > an intertropical front jetstream |
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the most marked thermal gradient to be found is @ .... especially .... .
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polar front
when it is over land in the winter |
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The polar front is where ...... .
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polar air
meets the subtropical air |
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Intertropical front is where ... .
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the subtropical air
meets the tropical air |
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The jetstream exists .... in the ..... .
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just below the tropopause
warm air of a Px system |
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At the polar front,
the jetstream will be in the ... air |
subtropical (warmer)
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at the intertropical front
the jetstream will be in the ... air |
tropical (warmer)
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Jetstreams appear on the surface chart to be in the ... . This is so because of the ... .
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cold sector
slope of the front with height |
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Max CAT @ Jetstreams
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level with or just above the jet core
@ warm air but @ cold polar air side of the jet. |
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Jetstream movement
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moves with the front
follows the Px sys overall direction > westerly |
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Surface wind speed/direction vs. free upper air:
Why? |
slows
and backs @ NH / veers @ SH *due to friction forces <> moving air & ground |
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The degree to which the surface wind is altered compared with the free air gradient wind is a function of ....
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1. Diurnal variation (day/night)
2. Surface variation (land/sea) |
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Diurnal variation @ Surface wind
By day: |
*Compared with the free air gradient wind :
> loses "less" strength & speed > backs only "slightly" *Compared with the night surf wind > stronger wind > veers |
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Diurnal variation @ Surface wind
By night: |
*Compared with the free air gradient wind :
> loses "more" strength & speed > backs "significantly" *Compared with the day surf wind > weeker wind > backs slightly |
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The surface wind by day will resemble the gradient wind more closely by .... (d/n)
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Day
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Wind change with hight?
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@ NH
Speed increase Veer in dir. @ SH Speed inc. Back in dir. |
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surface wind important to pilots?
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it affects aircraft during takeoffs and landings.
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Trade winds are ...
can extend up to ... . They blow from ... into ... |
*steady and predictable surface winds
*10,000 ft *the subtropical highs *the equatorial low (ITCZ) |
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Trade winds direction ?
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from NE @ NH
from SE @ SH (both easterly) |
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Land/sea breezes are a product of
... and ... that produce ... . |
*surface heating
*atmospheric convection currents *small local airflow circulation cells |
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Land/sea breezes are of particular importance to ...
Because : ... |
coastal airports
1. Determine LOCAL wind dir > sig diff from general 2. may cause turb./w.shr |
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Sea breeze occurs during ... on ...,
when ... . |
the daytime
hot sunny days the land heats up quicker than the sea |
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Land breeze occurs during ...
when ... , causing ... . |
night
the land cools quicker than the sea the air above land > cool and subside |
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Fohn wind effect
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* Air rises @ Hi ground > cooled @ DALR
* @ DP > SALR * Condensation > Cloud @ hill side * Moisture lost > rain / dew * Air dec. @ leeward * Lower water content > Higher Cnden. level * Longer warming period @ DALR * >> warmer / dryer air @ leeward |
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Fohn wind is a result of ... which generates .......
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*Fohn wind effect
*a wind that blows down lee side of the hill. |
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fohn wind effect can be seen in ...
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*Rocky Mountains (Chinook winds)
*The Alps |
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A katabatic wind is ... that flows ... .
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a local valley wind
"down" the side of a hill |
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An anabatic wind is ... that flows ... .
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a local valley wind
"up" the side of a hill |
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An airmass is ...
Features ? |
*a large parcel of air
1. fairly similar Temp and humidity 2. fairly constant ELR 3. all the air behaves in the same way when H/C/L > all throughout the airmass |
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A pressure system is ... that is ... .
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*a circulating airmass
*classified as either a low or high (get H/L twd center) |
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Low-pressure system, is also known as ... .
1.Pressure gradient : |
a depression
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Charac. of a low-Px system :
1.Pressure gradient : |
Surf. Px drops as you move toward its center
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Charac. of a low-Px system :
2. Airflow pattern : |
a. Convergence (inflow) @ lower layers
b. Rising air at the center c. Divergence (outflow) @ upper layers |
|
|
Charac. of a low-Px system :
3. Wind direction : |
CCW @ NH
CC @ SH |
|
|
Charac. of a low-Px system :
4. Airmass. |
*at least two different air masses
> cold and a warm air mass with fronts. |
|
|
Charac. of a low-Px system :
5.Movement |
*move faster
*have a shorter life span |
|
|
Low-Px systems : more intense than highs because ... .
|
they
1. are more concentrated in terms of area 2. have a stronger pressure gradient |
|
|
Flying toward LOW @ N.Hem,
an aircraft will experience ... drift. |
right (starboard)
|
|
|
Flying toward Hi @ N.Hem,
an aircraft will experience ... drift. |
left (port)
|
|
|
Depressions (low-Px systems)
developed and classified according to ... . |
their trigger phenomenon
|
|
|
Depressions are classification ?
|
1. Frontal depression
2. Thermal depression 3. Tropical storm depressions 4. Orographic depression |
|
|
Weather @ Low-Px system ?
(Brief) |
1. Cloud & related Wx (precept, etc)
> if unstable > vertical dev. 2 .Visibility may be good (except in rain showers) 3. Moderate to strong winds 4. Frontal Wx |
|
|
Weather @ Low-Px system :
1.Cloud : |
*Is present due to > Adiab. cooling of ascend. air
*instab. @ rising air > Vert. dev > cum. |
|
|
Weather @ Low-Px system :
2. Visibility : |
*Visibility may be good (except intherainshowers)
> Vert motion : carry away susp. particles |
|
|
Weather @ Low-Px system :
3. Winds |
Moderate to strong
> Marked Px grad. |
|
|
Weather @ Low-Px system :
4. Fronts : |
normally is the most prominent Wx
associated with a depression |
|
|
Trough?
|
a V-shaped extension of a low-Px system.
|
|
|
Wx @ Trough?
|
If unstable air > similar to Dep/cold front
e.g. Cu/CBs/TS |
|
|
High-pressure system, is also known as ... .
|
anticyclone
|
|
|
Charac. of a Hi-Px system :
1. Pressure gradient : |
*Surface Px rises moving toward center
*Weak Px gradient (wide isobars) |
|
|
Charac. of a Hi-Px system :
2. Airflow pattern : |
a. Convergence @ upper layers
b. Subsiding air at the center c. Divergence @ lower layers |
|
|
Charac. of a Hi-Px system :
3. Wind direction |
CW @ NH
CCW @ SH |
|
|
Charac. of a Hi-Px system :
4. Airmass |
*Usually only one air mass
> no defined fronts |
|
|
Charac. of a Hi-Px system :
5.Movement |
*Weaker Px gradient
> slow moving > more persistent > last longer |
|
|
Weather @ Hi-Px system :
Brief |
1. Clear upper skies : little/no low-level cloud
2. Light winds 3. Possible poor visibility @ low levels |
|
|
Weather @ Hi-Px system :
1. Clouds : |
*Clear/ little low level
> descending stable air > warmed > DP inc > RH dec |
|
|
Weather @ Hi-Px system :
2. Winds : |
*Light
> weak pressure gradient |
|
|
Weather @ Hi-Px system :
3. visibility : |
*possibly poor @ low levels
> descending air > brings & traps airborne particles > possible inversion |
|
|
Ridge?
|
U-shaped ext. of a high-Px system.
|
|
|
Airflow btw a low- and a hi-Px sys :
|
*is pressure-driven
1. Start @ surf. Hi-Px 2. Outward airflow > to center of Low 3. Rise to upper Hi 4. Outward flow > to an upper Low 5. Subsides > back to start! |
|
|
A front is ... .
|
a boundary between two different air masses
|
|
|
Front are produced due to ...... .
|
*different characteristics of the involved air masses
> give rise to distinct divisions btw adjacent air masses |
|
|
A front is shown as a line on a weather chart that represents ... .
|
the front’s surface position
|
|
|
Frontal activity ?
|
The interaction
btw at least two air masses as one air mass replaces another. |
|
|
Frontal depressions : develop when ...... .
|
> two different air masses meet (touch)
> but do not mix together > cuz one is warmer & less dense than the other |
|
|
Warm front?
|
> The boundary
> btw two air masses > where the warmer, less dense air mass > slides over the colder air mass @ the surface. |
|
|
Warm front pos. @ Wx charts ?!
Why? |
* frontal air @ altitude
> well ahead of depicted position @ Wx chart. * very shallow slope of 1:150 |
|
|
Top of a warm front,
which is usually characterized by ... , could be up to ... of the surface front. |
*cirrus clouds
*600 nautical miles ahead |
|
|
A warm front is ... the warm (air mass) sector
|
at the leading edge of
|
|
|
Warm front is ... the cold front @ depression.
(position) |
ahead of
|
|
|
Wx charac. @ Warm front,
As it approaches : Brief |
1. Lowering cloud base
2. Poor visibility 3. Falling atm. Px |
|
|
Wx charac. of approaching Warm front :
1. Clouds : |
* Base is lowering
> Cirrus > Cirro-stratus > Alto-stratus + poss. Virga > Nimbo-stratus + inc Rain. |
|
|
Wx charac. of approaching Warm front :
2. Visibility : |
* Poor
* Due to > inc low-level clouds > more consistent rainfall |
|
|
Wx charac. of approaching Warm front :
3. Px |
* Falling
> cuz warm fronts @ front of low-Px |
|
|
Wx charac. @ Warm front,
As it passes : Brief |
1. inc Temp > arriving of Warm sec.
2. Low-level cloud base/ fog. 3. Wind veer @ NH 3. Px stop falling / may rise 4. Gen good vis. (ex. in cd/fg) |
|
|
Cold front?
|
> The boundary
> btw two air masses > where the colder, denser air mass > slides under the warmer air mass > from the surface upward |
|
|
Cold front pos. @ Wx charts ?
Why? |
* Accur. displays the front’s actual position
* Front's up. pos > is virtually over the surf. pos. > steep slope of 1:50 |
|
|
Because ... , there is little warning of the approach of a cold front
|
the slope of the cold front is relatively steep
|
|
|
A cold front is ... the warm (air mass) sector (position)
|
at the trailing edge of
|
|
|
A cold front is generally ... the warm front in a depression
(position) |
behind
|
|
|
Warm front move ... than a cold front, at about ...
|
slower
2/3 the GW component |
|
|
Cold & Warm fronts move @ different speeds;
Why ? |
* Warm air
> tend. slide over denser cold air > Force moving it (GW) : move up & Hor. * Denser cold air > little res. form W. air > driving force : solely Hor. |
|
|
Wx charac. @ Cold front,
As it approaches : Brief |
1. Cu/CBs > +RA/ TS/ Turb./ W.shr
2. Poor visibility > hvy vert. cld + const. rain 2. Falling atm. Px |
|
|
Wx charac. @ Cold front,
As it passes : Brief |
1. Sudden drop @ Temp > cold sec.
2. Clear skies + iso Cu. 3. Wind veer @ NH 4 Px stops falling / may rise |
|
|
An occluded front is ..... .
It occurs because ..... . |
* a combination of
> both a cold and a warm front * the faster moving Cold front > catches up with the warm front |
|
|
Occluded front
occurs first ... , where ... . |
* near the center of t he depression
* shortest dist. btw two fronts is. |
|
|
Turbulence is ..... .
|
the eddy motions in the atmosphere
|
|
|
Turbulence is mainly considered to be ... ,
2 main forms being : |
vertical gusts
1. Convection Turb. > Solar Rad. heating grd > rising therm. current. 2.Obstruction and orographic > terrain generated. |
|
|
Horisontal form of Turbulence :
|
1. Jetstreams
2. Wake turbulence |
|
|
Surface turbulence?
Is caused by : ........ . |
* Surf. wind
> blowing over surf. obst. (hills, blg, trs) > creating turbulent eddies |
|
|
Windshear?
|
* Any variation
of wind speed and/or direction from place to place * Including vertical updrafts/downdrafts |
|
|
A Windshear's magnitude?
|
* The stronger the Chx of w. spd/ dir.
* and/or the shorter the distance within which it occurs, > the greater is the windshear |
|
|
Most forms of windshear are found at ... .
|
* low levels
> below 3000 ft |
|
|
The term low- level windshear is used to specify the wind-shear along ....... . (3)
|
* a final approach path prior to landing,
* along a runway, * along a T.O. and initial climb-out flight path. |
|
|
Low-level windshear includes :
|
1. CAT
2. Frontal passage 3. Microburst & thunderstorm gusts. |
|
|
Windshear detection?
(The idea) |
* ID a difference in
> wind (dir. &/or spd) > &/or Temp btw 2 places * Or ID certain Wx phenomenon, > like CBs, > that give rise to possible W.sheer |
|
|
Windshear detection?
|
1. Pilot appreciation of CBs/ +RA/ terrain/ ...
2. Aerodrome equipment 3. Aircraft warning equipment |
|
|
Phenomena that should alert the pilot instinctively of the possibility of windshear
|
CBs
+RA / TS Fronts (W. dir) Virga (Inversion) Land/ see brz Terrain |
|
|
Windshear hazard @ aviation
(brief) |
It can affect the flight path
and airspeed of an aircraft |
|
|
Windshear affect @ aircraft?
|
* Reduced IAS > due to reduced Wnd spd
* Inc of effective Wt > due to D.draft > requires pith up > inc effective Wt. further * Overshoot / undershoot W.sheer |
|
|
A microburst ?
|
* a severe downdraft (vertical wind)
emerge from base of a CB during a TS * Also : severe form of W.shear |
|
|
Microbursts are found in ....
and are associated with ... |
* Close / underneath, mature CB
* TS. |
|
|
Microburst features: (5)
|
* Are highly concentrated
* Are about 5 km across * Often centered @ middle of TS * Last a few min. (~10min) * Can reach up to 3000 ft/min |
|
|
Microburst is a result of ... due to ...
|
the D.draft breaking out of base of cloud
* being colder than surrounding air |
|
|
Indications of a microburst : (5)
|
1. Mature CBs with TS activit y, esp RA
2. Roll cloud around CB 3. Virga rain 4. Flight path & IAS fluctuations 5. Wind direct ion and speed Chx (rep/msr) |
|
|
Why Virga could indicates a possibly severe microburst?
|
* RA evap. before reaching grd
> Absorbs latent heat out of surr. air > Creates denser/ heavier air > Causing D.draft fall @ even greater rate |
|
|
Microburst effect @ aircraft
|
@ Entrance:
* Updrafts & increased HWD > Energy gain > NU > IAS rise > ROD reduced = Overshoot effect @ Center * Strong downdraft > energy loss > ND > IAS fall > ROD inc @ Exit > Increased TWD > energy loss > IAS fall sharply > ROD inc == Overal effect > Undershoot |
|
|
Wind gust factor
An indication of ...... . |
how much wind speed change to expect
@ varying wind conditions |
|
|
Wind gust factor
Formula |
(Max Wind spd - Min) / Mean wind spd
|
|
|
Lenticular clouds
Are indication of ... |
standing (mountain) wave CAT
|
|
|
Lenticular clouds are found @ ...
|
* height @ rising air
* above the D.wind side of a range of hills |
|
|
Lenticular clouds
often extend for up to .... of a line of hills and @ height of up to ... . |
100 nautical miles downward
25,000 ft |
|
|
CAT is an acronym for ...,
in which ... |
* clear air turbulence
* there is no signs of > visible moisture content @ turbulent air |
|
|
Examples of CAT are :
(5) |
1. Low-level CAT
2. Jetstreams 3. Fronts 4. TSs 5. Wake turbulence |
|
|
The most severe CAT can be found .... .
|
level or just above the jet core
@ the warm air @ the cold air/polar side of the jet |
|
|
Low-level CAT
Caused by .... (4) |
a. Temperature inversions
b. Surf/grd wind mixing c. c. Local surface winds (breezes) d. Terrain-generated winds |
|
|
CAT detection ?
can only be detected by : ... |
* One of hardest
* No specific equip. 1. Using met evaluation of the prevailing conditions 2. ID locations of conditions that give rise to CAT |
|
|
Good indications of possible CAT :
(4) |
1. any reported wind &/or Temp chx btw 2 places
2. presence of CBs / Lents / fronts / JS 3. Large, rapid fluctuation @ TAT (~ ±10°C) @ few S. 4. Broken engine trails of preceding AC |
|
|
Wake turbulence is .... .
|
the disturbed airflow
called wing-tip vortices created behind wings of a moving AC |
|
|
Wake turbulence can be a serious hazard to .... .
|
* lighter aircraft following heavier aircraft
|
|
|
Wake turbulence is extremely hazardous during ..... .
(4) |
(for light beh. hvy)
* takeoff * initial climb * final approach (including t he circuit ) * landing phases |
|
|
Wake turbulence charac. depend on ..... .
(5) |
* aircraft’s gross weight
* wingspan * airspeed * configuration * attitude. |
|
|
Wake turbulence avoidance ?
|
separation up to 5 min
by ATC btw light AC folioing hay |
|
|
What is icing?
|
* Change of a state of water to a solid form
@ Temp < 0 * either from 1. vapor > sublimat ion 2. Water droplets > SWD |
|
|
Sublimation?
The process of ... when ... causing ... |
* turning water vapor immediately into ice
* DP / Atual Temp < freezing * hoar frost (type of icing) |
|
|
Dewpoint with regard to sublimation is called ...
|
frost point
|
|
|
what are SWDs ?
|
* Very small liquid water drops (40-2000μm)
* exist in a nonfrozen liquid form @ Temp as low as -45°C |
|
|
What happens @ SWD impact with sth (AC skin) ?
|
* freeze partially @ contact
> with colder, sub-zero * turn progressively into ice > as it is washed back > due to release of LH |
|
|
For each ... of SWD, ... of the water drop
will change to ice on impact . |
degree below zero
1/80th |
|
|
Airframe icing is only possible between ... .
because ..... |
0 and –45°C
* any moisture below –45°C > Ice crystal > do not stick to airframe |
|
|
Airframe icing occurs in ... when ... ,
causing ... . |
* freezing clouds
* SWDs are present * rime and/or clear ice |
|
|
Conditions presenting icing risk ?
|
* Where moisture is present
* TAT @ flight / OAT @ grn > is btw +10°C & –40/45°C. |
|
|
Icing is particularly hazardous at .... .
|
slow flight phases of flight
|
|
|
Icing hazards to aviation
|
1. Adverse AD perf. effects
2. Control surface effects 3. Inc of AC weight effects. 4. Reduced engine power 5. Vent blockage effects 6. Degraded nav / radio comm. effects |
|
|
Icing hazards to aviation
1. Aerodynamic problems : |
* disrupts airflow pattern @ wings
a. Reduced stalling angle b. Reduced max lift capability c. Increased Vs d. Increased D e. Reduced / loss of lift |
|
|
Icing hazards to aviation
2. Control surfaces : |
restricted movement
even loss of control |
|
|
Icing hazards to aviation
3. Wight : |
Chx of CG pos
Chx of balance of Ctl surf. / props / .. > causing vibration |
|
|
Icing hazards to aviation
4. Engine power : |
* restricts the airflow into the engine
> power loss > even engine failure |
|
|
Icing hazards to aviation
5. Vents |
Blocked pitot/ static
> errors @ pressure-driven flight instruments |
|
|
Carburetor icing,
where and how ? |
@ Piston engines
> happens @ venturi / around hrottle valve > where acceleration of the air > causes T fall up to 25°C > plus heat absorption of evaporating fuel |
|
|
Carb ice hazard ?
|
* can disturb /prevent air/ fuel flow
> to eng manifold > causing : power loss / rough run / stoppage |
|
|
Throttle icing is more likely to occur at ....
because ... |
* low power settings
* partially closed butterfly > creates venturi cooling effect |
|
|
Meteorological visibility
Defined as ... . |
the greatest
horizontal distance @ which a specified object can be seen in daylight conditions |
|
|
Meteorological visibility
Is a measure of ... . |
how transparent the atmosphere is
to the human eye |
|
|
Visibility is reduced whenever ...... .
e.g : ..... . |
* particles are present @ atmosphere
> that absorb the light * e.g. > water, ice, > pollution, sand, > dust, volcanic ash. |
|
|
Poor visibility is usually associated with ... ,
where the .... is ... , |
* stable air
* moisture &/or atmospheric contam. > kept trapped (esp. low level) |
|
|
* Sun's effect @ visibility
|
* flying Down-sun > good
* into sun > bad + Glare |
|
|
Conditions reduce visibility?
(brief) |
1. Presence of particles
2. Stable air 3. Sun's position |
|
|
Most important visibility to the pilot ?
|
* AC to the ground > Slant / oblique visibility
> esp. @ T.O. / Land direction * May be very diff. from Met vis. |
|
|
How is visibility reported ?
|
1. General visibility > fr. overall met reports
2. RVR > for instrument landings |
|
|
What's General visibility ?
It's reported in ... |
* the least distance
> visible from the point of the observation > in all directions. * km, or in very poor conditions, in m. |
|
|
What is RVR?
|
> Highly accurate
> instrument-derived > visibility measurement * Represents the range @ which the runway’s high-intensity lights can be seen in the direction of landing. |
|
|
RVR is used, when available,
as ... for ... . |
* a visibility minimum
* low-visibility prec. app. landings |
|
|
Smog is .... (See Q: What is fog? page 231.)
Usually found ... . |
* a combination of smoke & fog
* under an inversion layer (blanket) |
|
|
An inversion layer acts like ... , in which it ... .
|
* a blanket
* stops vertical convective currents. |
|
|
The thermal equator is ... .
|
* the position
> of the maximum thermal Temp > around the earth’s surface |
|
|
Position of the thermal equator :
|
* Moves according to > Sun's heating
> varies widely with season > Summer : twd poles @ both hem > greater heat @ higher Lats |
|
|
Thermal equator
vs. Global equator |
* Varies considerably > over land
> Higher seasonal T change over land * Close to each other @ SEa |
|
|
ITCZ ?
|
* where converging air masses
* meet near the thermal equator. |
|
|
ITCZ movement is a function of ...
in which is ... . |
* seasonal heating
* much greater over land than over sea. |
|
|
The effect of the ITCZ determines ... over ... .
|
* the weather pattern
* a significant portion of the globe |
|
|
What are TRSs?
Found in ? |
* Tropical revolving storms
> are deep, intense depressions * Found in equatorial regions > around the ITCZ |
|
|
TRSs are known as
cyclones in the ... , hurricanes in the ... , and typhoons in the ... . |
Indian and Pacific Oceans
Caribbean and Americas China Sea area |
|
|
TRSs requirements for formation ?
|
1. Large body of water > ocean
2. Sea Temp of at least 27°C 3. 5 to 20 degrees of latitude > Coriolis effect |
|
|
When do TRSs form?
Why? |
* in late summer or early autumn
* cuz > TRS needs heat > achieved only aft. prolonged heating |
|
|
TRSs do not form over ... and die out
when they pass ... or move to .... |
cold seas
over land colder sea region |
|
|
Primary method of preflight met briefings
|
1. Using facilities, info, and doc.
> available @ aerodrome briefing areas. 2. Using a telephone service > to call an aviation authority met office |
|
|
AIRMET?
|
> a recorded telephone message
> that gives the met. forecast > for a particular area. |
|
|
AIRMET can be accessed by ... .
|
* area
* Tel @ AIRMET Areas Chart |
|
|
A meteorologic report is .... .
|
an observation of the actual Wx
@ a specific time, either past or present. |
|
|
Common aviation meteorologic reports ?
(3 cat , 8 items) |
1. METARS, SIGMETS, and SPECI
2. ATIS 3. In-flight weather reports > Volmets > ATIS > radio comm with : ATC / FIS |
|
|
What are METARs?
(format) |
> a written,
> coded > routine aviation Wx report for an aerodrome. |
|
|
METAR is ...
given by ... at ... . |
* an observation of the actual Wx
* a meteorologic observer * the aerodrome |
|
|
Cloud base in a metar is given ... .
(reference) |
above ground level
(AGL) |
|
|
A weather trend is usually attached to ... .
commonly referred to as ... . |
* an aerodrome weather report (METAR)
* a landing forecast |
|
|
The trend is ....... .
|
* a forecast
> of any significant Wx changes > expected in the next 2 hours > after the time of the report |
|
|
A Wx trend is described using ... .
|
the normal coded weather format and abbreviations
|
|
|
NOSIG @ Wx report?
|
a trend for
"no significant change " |
|
|
Cloud bases @ trend are given .... .
(Reference) |
above aerodrome level (AAL)
|
|
|
A trend can only be given by ...,
whereas a report can be given by ... . |
* a qualified forecaster
* just an observer |
|
|
Because a trend forecast period is much shorter than a normal aerodrome forecast, it should be ... .
|
much more accurate
|
|
|
A SIGMET
is ... that advises of ... that may ... in ... . |
* a meteorologic report
* significant meteorologic (SIG/MET) conditions * affect the safety of flight operations * a general geographic area |
|
|
The criteria for raising a SIGMET include
(8) |
1. Active TSs
2. TRSs 3. Severe line squalls 4. +RA 5. Severe turbulence 6. Severe airframe icing 7. Marked mountain waves 8. Widespread dust or sandst orms |
|
|
A SPECI is .... for ... .
It is generated whenever ... . e.g ... . |
* an Aviation Selected Special Weather Report
* an aerodrome * a critical meteorologic condition exists * W.shear / microbursts |
|
|
A SPECI is similar in presentation to ... .
|
a METAR
|
|
|
ATIS is acronym for ...
|
Automatic Terminal Information Service
|
|
|
(ATIS) is ...
on an appropriate ... that gives ... It's there to ... . |
* a prerecorded tape broadcast
* VOR or VHF channel * current info on AD operations and Wx * reduce theworkload on ATC |
|
|
The ATIS message is changed with ... ,
|
any significant change
in the reported conditions |
|
|
each new ATIS message has ... .
to ... |
* a new alphabetical designator prefix
* distinguish the current from the old. |
|
|
VOLMET is ... on a ... frequency
that includes ... (4) of ... . within ... . |
* a continuous broadcast
* VHF/HF 1. The actual Wx report 2. The landing forecast 3. A trend for the 2 hours following 4. A SIGMET (if any) * several selected aerodromes * a given region |
|
|
What is a meteorologic forecast?
|
a prediction / prognosis,
> of what the Wx is likely to be > for a given route / area / aerodrome. |
|
|
Common types of aviation forecasts (3)
|
1. Area forecasts > for preflight briefings
2. Aerodrome forecasts 3. Special forecasts |
|
|
Cloud bases @ area forecasts
are given above ... . |
mean sea level
|
|
|
TAF is acronym for ...
|
Terminal Aerodrome Forecast
|
|
|
What is a TAF?
given by ... based @ ... |
> coded
> routine > weather forecast > for an aerodrome. * a qualified met forecaster * the aerodrome |
|
|
Cloud base in a TAF is given above ... .
|
aerodrome level (AAL)
|
|
|
TAFs
> issued for a ... period > updated every ... . Could also be ... . |
9-hour
3 hours 24 hr / 6hr > less accurate |
|
|
What is a special forecast?
when is it requested? |
* meteorologic forecasts
* for flights > over long routes > outside the coverage of the local countries’ area forecast . |
|
|
Special forecasts can include ..... .
|
* forecasts (TAFS) for
> the dep. , > dest. , > and up to three alt. aerodromes. |
|
|
BECMG means “ ... ”
Is followed by ... . Indicates ... . |
* Becoming
* a 4-fig time group > two different whole UTC hrs * a permanent change > in the forecasted conditions > occurring at some time > during the specified period |
|
|
TEMPO indicates ... in ...
lasting ... or if recurring, lasting ... . |
* a temporary variation
* the general forecasted weather * less than 1 hour * less than half the trend or TAF period |
|
|
Once a TEMPO weather events have finished, ... .
|
the original weather will prevail.
|
|
|
A TEMPO can relate to ... as well as ... in
wind, visibility, weather, or clouds. |
improvements
deteriorations |
|
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INTER indicates ... in ...
that are ..., or basically: ... . |
* intermittent variations
* the general forecasted weather * more frequent than TEMPOs * conditions fluctuating almost constantly |
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An INTER can relate to ... as well as ... in wind, visibility, weat her, or clouds
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improvements
deteriorations |
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Once the INTER weather events are finished, ... .
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the original weather will prevail.
';'. |
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GRADU indicates ... in ...
at approx. ... to ... . |
* gradual change
* the original weather * a constant rate * a different and new Wx condition |
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RAPID indicates ... of ... .
(period) in ... , to ... . |
* a rapid change
* the original weather * less than 30 minutes * a new & different prevailing Wx condition |
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PROB is used in weather forecasts
when ...... , in which the probability is .... . |
* forecaster : uncertain if Wx conditions
> will occur or not * less than 50 percent |
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CAVOK conditions ?
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1. Visibility : = / > 10 km
2. No > clouds below 5000 ft > or below highest MSA : the greater > CB @ any altitude 3. No > precipitation, > TS. > shallow fog > low drifting snow |
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@ CAVOK conditions :
term CAVOK is used to replace ... in meteorologic reports and forecasts. |
visibility,
RVR, weather, and clouds |
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CAVOK does not mean ... .
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clear blue skies
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