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Question 155-1 : Flight from lisbon to kingston..considering the route segment between 30°w and 50°w, at fl 390 the forecast mean temperature is. 395 ? [ Learning aircraft ]
56°c.
Question 155-2 : What is the approximate value of atmospheric pressure at 11000 m amsl in comparison to the atmospheric pressure at mean sea level ?
One fourth.
Ecqb03 july 2016
Question 155-3 : Which type of inversion can lead to fog formation due to the temperature of air in contact with the surface dropping below its dew point when it contacts a colder surface ?
Ground inversion
Ecqb03 july 2016
Question 155-4 : You are flying at fl 300 where the outside air temperature is 57.5°c and the pressure at msl is 1013.25 hpa..if you assume that the difference between the actual temperature and the temperature in the isa is valid for the whole troposphere, then the true altitude is ?
28500 ft.
Ecqb03, august 2016
Question 155-5 : At what flight level is the zero degree isotherm at the equator ?
Fl 180.
. the zero degree isotherm in the 'polar regions' is at ground level... the zero degree isotherm in 'temperate regions' is at mean sea level in winters and at about 10000 feet in summers... the zero degree isotherm in 'tropics' area 15° 30° n and s of the equator is at about 16000 feet... the zero degree isotherm at the equator is at about 18000 ft fl180.
Question 155-6 : Why are polar regions colder than equatorial regions ?
Because the angle of incidence of the solar radiation is very small in polar regions.
Ecqb03, december 2016
Question 155-7 : Which of the following is true concerning atmospheric pressure ?
It decreases with height.
.the decrease of 1 hpa/27ft is only applicable at the lower levels of the troposphere, as you go up and air pressure decreases, the change of height per 1 hpa increases at msl 1hpa/27ft, at fl180 it's 50ft/hpa and at fl390 it's 105ft/hpa.
Question 155-8 : The vertical temperature gradient lapse rate in the international standard atmosphere isa is ?
6.5°c per 1000 m.
Question 155-9 : What is the approximate height of the tropopause between keflavik and helsinki. 406 ?
Fl 320.
. 462.you will find fl 325, closest answer is fl 320.
Question 155-10 : For a flight from the azores to the bermudas, the tropical tropopause is to be found at a height of approximately . 409 ?
51000 ft 12000 metres.
Question 155-11 : Tropopause altitude at 38°n 19°w is. 410 ?
Fl 320.
Question 155-12 : Assuming a normal vertical temperature gradient, at what altitude will the freezing level above shannon be found. 411 ?
Fl 60.
Question 155-13 : The temperature deviation from isa to the nearest °c overhead charleston at fl 340 is. 419 ?
+5.
.the temperature lapse rates of the troposphere is mean value 0.65°c/100 m or 2°c/1000 ft...in isa, temperature at fl340 should be 15 + 34 x 2°c = 53°c...as the current temperature at that level is 48°c, you can say that at fl340 it is currently isa+5...it is 5°c warmer than isa.
Question 155-14 : The maximum possible temperature at north pole is ?
Dependent on the seasons.
Question 155-15 : In the northern hemisphere, the force that causes a deviation to the left from the surface wind relative to the geostrophic wind is ?
Frictional force.
Ecqb04, january 2018.... 498.at the surface and at low elevations, friction will slow the air, and hence the coriolis will be less effective in its deflection of the wind..the flow turns across the isobars, you have more flow into the low pressure system, giving convergence and feeding the convection.
Question 155-16 : The wind indicator for a weather observation receives the measured value from an anemometer. where is this instrument placed ?
On a mast 8 10 m above the runway.
Question 155-17 : The geostrophic wind is greater than the gradient wind around a low pressure system because the ?
Centrifugal force opposes the pressure gradient.
.we have a geostrophic wind when the pressure gradient force pgf is exactly balanced by coriolis force. 582.it is only happens when isobars are straights and parallels...if the isobars are curved an additional force, centrifugal force, is introduced and always tries to throw the parcel of air outwards from the centre of its rotation and the resulting movement of air is called the gradient wind. 583.with an area of high pressure anticyclone the centrifugal force is acting in the same direction as pgf, effectively increasing it. coriolis balances the total force pgf + centrifugal force and the gradient wind is 'high round a high' i.e. for a given gap between the isobars the gradient wind is stronger than the geostrophic wind...with an area of low pressure cyclonic system the centrifugal force is opposing the pgf, effectively decreasing it. coriolis balances the total force pgf centrifugal force and the gradient wind is 'low round a low' i.e. for a given gap between the isobars the gradient wind is weaker than the geostrophic wind.
Question 155-18 : The geostrophic wind is less than the gradient wind around an anticyclone because the ?
Centrifugal force is added to the pressure gradient.
.we have a geostrophic wind when the pressure gradient force pgf is exactly balanced by coriolis force. 582.it is only happens when isobars are straights and parallels...if the isobars are curved an additional force, centrifugal force, is introduced and always tries to throw the parcel of air outwards from the centre of its rotation and the resulting movement of air is called the gradient wind. 583.with an area of high pressure anticyclone the centrifugal force is acting in the same direction as pgf, effectively increasing it. coriolis balances the total force pgf + centrifugal force and the gradient wind is 'high round a high' i.e. for a given gap between the isobars the gradient wind is stronger than the geostrophic wind...with an area of low pressure cyclonic system the centrifugal force is opposing the pgf, effectively decreasing it. coriolis balances the total force pgf centrifugal force and the gradient wind is 'low round a low' i.e. for a given gap between the isobars the gradient wind is weaker than the geostrophic wind.
Question 155-19 : In the lower layers of the atmosphere due to friction the wind changes direction towards the low pressure area because ?
Wind speed decreases and therefore coriolis force decreases.
. 498.at low elevations, friction will slow the air, and hence the coriolis will be less effective in its deflection of the wind.
Question 155-20 : The most frequent wind direction in a valley caused by thermal effects is toward the ?
Mountain during daylight hours.
.during the day, the sun heats up valley air rapidly. this causes it to rise, causing a warm, upslope wind valley breeze..at night, the process is reversed. mountain air cools rapidly at night and 'falls' downslope, causing a wind going in the valley mountain breeze.. 499.a mountain breeze and a valley breeze are two related, localized winds that occur one after the other on a daily cycle.
Question 155-21 : Convective activity over land in mid latitudes is greatest in ?
Summer in the afternoon.
.thunderstorms may occur in the summer months, in the afternoon or evening, due to convective activity the land warms causing convective lifting = cb.
Question 155-22 : Which forces are balanced with geostrophic winds ?
Pressure gradient force, coriolis force.
.we have a geostrophic wind when the pressure gradient force pgf is exactly balanced by coriolis force. 582
Question 155-23 : How does moderate turbulence affect an aircraft ?
Changes in altitude or attitude occur but the aircraft remains in positive control at all times.
.procedures for air navigation services air traffic management pans atm, doc 4444.instructions for air reporting by voice communications.moderate conditions in which moderate changes in aircraft attitude and/or altitude may occur but the aircraft remains in positive control at all times. usually, small variations in airspeed. changes in accelerometer readings of 0.5 g to 1.0 g at the aircraft's centre of gravity. difficulty in walking. occupants feel strain against seat belts. loose objects move about...severe conditions in which abrupt changes in aircraft attitude and/or altitude occur, aircraft may be out of control for short periods. usually, large variations in airspeed. changes in accelerometer readings greater than 1.0 g at the aircraft's centre of gravity. occupants are forced violently against seat belts. loose objects are tossed about.
Question 155-24 : Which degree of aircraft turbulence is determined by the following icao description.'there may be moderate changes in aircraft attitude and/or altitude but the aircraft remains in positive control at all times. usually, small variations in air speed. changes in accelerometer readings of 0.5 to 1.0 g ?
Moderate.
.procedures for air navigation services air traffic management pans atm, doc 4444.instructions for air reporting by voice communications.moderate conditions in which moderate changes in aircraft attitude and/or altitude may occur but the aircraft remains in positive control at all times. usually, small variations in airspeed. changes in accelerometer readings of 0.5 g to 1.0 g at the aircraft's centre of gravity. difficulty in walking. occupants feel strain against seat belts. loose objects move about...severe conditions in which abrupt changes in aircraft attitude and/or altitude occur, aircraft may be out of control for short periods. usually, large variations in airspeed. changes in accelerometer readings greater than 1.0 g at the aircraft's centre of gravity. occupants are forced violently against seat belts. loose objects are tossed about.
Question 155-25 : In a land and sea breeze circulation the land breeze blows ?
During the night and is weaker than the sea breeze.
. 600
Question 155-26 : A high pressure area slack pressure gradient covers part of the mediterranean sea and coastal region during the summer. what surface wind direction is likely at an airport at the coast on a sunny afternoon ?
Sea to land.
.during a sunny afternoon sea breeze is likely to occur. 601..we should expect a wind from the sea. 544
Question 155-27 : A mountain breeze katabatic wind blows ?
Down the slope during the night.
.during the day, the sun heats up valley air rapidly. this causes it to rise, causing a warm, upslope wind valley breeze..at night, the process is reversed. mountain air cools rapidly at night and falls downslope, causing a wind going in the valley mountain breeze.. 499.a mountain breeze and a valley breeze are two related, localized winds that occur one after the other on a daily cycle.
Question 155-28 : Generally northern hemisphere winds at 5000 ft/agl are south westerly while most of the surface winds are southerly. what is the primary reason of difference between these two wind directions ?
Friction between the wind and the surface.
.at low elevations, friction will slow the air, and hence the coriolis force will be less effective in its deflection of the wind.. 561.as the elevation decreases the direction backs changes direction in an counter clockwise motion in northern hemisphere..at mid latitude, over land, wind speed in friction layer decrease by 50%. angle between wind direction and isobars changes by 30° value to be used in examinations.
Question 155-29 : Friction between the air and the ground results in the northern hemisphere in ?
Backing of the wind and decrease of wind speed at the surface.
.at low elevations, friction will slow the air, and hence the coriolis force will be less effective in its deflection of the wind.. 561.as the elevation decreases the direction backs changes direction in an counter clockwise motion in northern hemisphere..at mid latitude, over land, wind speed in friction layer decrease by 50%. angle between wind direction and isobars changes by 30° value to be used in examinations.
Question 155-30 : What degree of turbulence, if any, is likely to be encountered while flying through a cold front in the summer over central europe at fl 100 ?
Severe turbulence in cb cloud.
Question 155-31 : You are flying at 2500 ft/agl above ground level , the wind is 180°, and intend to land at an airport, at sea level directly below. from approximately which direction would you expect the surface wind mid latitude, northern hemisphere ?
South southeast.
.at low elevations, friction will slow the air, and hence the coriolis force will be less effective in its deflection of the wind..in northern hemisphere, at mid latitude, over land, wind speed in friction layer decrease by 50%, the wind in the friction layer blows across the isobars towards the low pressure. angle between wind direction and isobars changes by 30° value to be used in examinations..at 2500 ft you will be out of the friction layer. on the ground, the direction will be 180° 30° = 150° south southeast direction..in the northern hemisphere, the friction layer decreases the wind direction anti clockwise.
Question 155-32 : What units are used to report vertical wind shear ?
Kt/100 ft.
Question 155-33 : What name is given to the jet stream lying across india a . 262 ?
Tropical jet stream.
.tropical jet stream = tropical easterly jet = equatorial jet stream = the only one blowing from east to west during summer season.. 533
Question 155-34 : An aircraft is flying through the polar front jet stream from south to north, beneath the core. how would the oat change, in the northern hemisphere, during this portion of the flight ?
It decreases.
.the polar front jet stream runs from west to east, and it will be found in the warm air of the ferrel cell sub tropical air mass. 575.if you cross below the jet stream northern hemisphere and you are flying from south to north, then you are flying from the warm subtropical air into the colder polar air..the outside air temperature oat will decrease.
Question 155-35 : What is the average height of the arctic jet stream core ?
20000 ft.
.average height of the arctic jet 20000 ft..average height of the polar front jet 30000 ft...the artic jet is at a higher latitude than the polar front jet, hence at a lower height tropopause is lower at the poles than the equator...arctic jet stream = 20000 ft..polar front jet stream = 30000 ft..subtropical jet stream = 40000 ft.
Question 155-36 : What is the approximate ratio between height and width for a jet stream cross section ?
Ratio is 1/100.
.for examination purposes we assume a jet stream to be about 2000 nm long, 200 nm wide and 2 nm deep. this gives an approximate ratio between height and width of 1/100.
Question 155-37 : Which jet stream blows all year round, over the northern hemisphere ?
The subtropical jet stream.
.the subtropical and polar front jets are present throughout the year..the polar night jet is only active during the winter months of the northern hemisphere and is located at 60° north..the equatorial jet is only present during the northern hemisphere summer.
Question 155-38 : What is the average height of the jet core within a polar front jet stream ?
Question 155-39 : An aircraft is flying from south to north, above the polar front jet stream, at fl 400 in the southern hemisphere. what change, if any, in temperature will be experienced ?
It decreases.
.flying from south to north in the southern hemisphere means that on crossing the polar front the aircraft will go from the cold air mass polar maritime to the warm air mass tropical maritime...at fl400 the aircraft will be above the tropopause...the tropopause in the warm air will be higher and colder than the tropopause in the cold air so the aircraft will note a decrease in temperature.
Question 155-40 : A wind speed of 350 kt within a jet stream core should be world wide regarded as ?
Possible but a very rare phenomenon.
.the highest recorded jet stream speed 354 kt 656 km/h , above isle of south uist scotland , 13th december 1967...the jet stream varies from about 80 to 350 nm wide and 1 to 3 nm thick. its strongest winds are generally encountered at about 30000 feet..jet stream winds usually have a speed of 130 to 260 kt.
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