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Question 145-1 : According to the extract of the surface isobar map the surface wind direction over the sea is approximately . 365 ? [ Certification weather ]

140°

Admin . 463.in the northern hemisphere if you stand with your back to the wind low pressure is on your left buys ballot's law .we are in southern hemispere situtation is reversed .if you stand with your back to the wind low pressure is on your right so the wind blows parallel to the isobars from 130° .over sea wind speed in friction layer decrease by 30% the wind in the friction layer blows across the isobars towards the low pressure angle between wind direction and isobars changes by 10° so answer is 140° exemple 245 140°.

Question 145-2 : In appendix are shown four sections of the 700 hpa wind chart the diagram representing most accurately the wind direction and speed is . 366 ?

030°/30 kt diagram a

Admin .if you stand with your back to the wind in the northern hemisphere low pressure is on your left buys ballot's law .in the southern hemisphere if you stand with your back to the wind low pressure is on your right as in diagrams a and c .on upper wind charts the 'feathers' on the wind arrows are on the low pressure/low isohypse side of the arrow which is only correctly shown in diagram a

Question 145-3 : At fl 300 between geneva and tunis what mean wind would be most likely . 367 ?

245°/50 kt

Admin . 630.wind direction is from 230+240+250+260 /4 = 245° .wind speed is 60+35+45+55 /4 = 48 75 kt exemple 253 245°/50 kt.

Question 145-4 : The mean wind that may be expected to affect the route segment from the coast of se england to geneva at fl 270 is . 367 ?

220/70kt

Admin .be careful we are looking at the wind only for the part from the coast of se england to geneva not from dublin to tunis .over manche at fl240 wind is 200°/55 kt .before geneva at fl240 wind is 220°/55 kt .over manche at fl300 wind is 230°/80 kt .before geneva at fl300 wind is 240°/80 kt .whitout calculation answer 220/70 seems to be the mean wind at fl270 exemple 257 220/70kt.

Question 145-5 : Judging by the chart what wind speeds can you expect at fl 310 above london . 372 ?

90 kt

. 632.a jet stream is passing right above london at fl310 .pennants correspond to 50 kt .feathers correspond to 10 kt .half feathers correspond to 5 kt .1 pennant + 4 feathers = 90 kt exemple 261 90 kt.

Question 145-6 : When in the northern hemisphere at the same latitude the distance between isobars is equal then ?

The gradient wind in a low pressure area is weaker than in a high pressure area

Pressure gradient is the difference in pressure between high and low pressure areas wind speed is directly proportional to the pressure gradient this means the strongest winds are in the areas where the pressure gradient is the greatest . the stronger the pressure gradient the more tightly packed the isobars are the stronger the wind speed exemple 265 The gradient wind in a low pressure area is weaker than in a high pressure area.

Question 145-7 : Which of the following statements is correct concerning the geostrophic wind ?

It is present at latitudes higher than about 15 degrees north/south

Admin .to have a geostrophic wind we need to have a pressure gradient force and coriolis force create by earth's rotation and depending on geographic latitude .we need to have two differents air mass to have a pressure gradient force pgf . 564.since the earth rotates objects that are above the earth apparently move or are deflected if they are already moving owing to it's rotation this apparent motion is caused by the coriolis force .in the northern hemisphere objects will be deflected to their right while in the southern hemisphere objects will be deflected to their left .the magnitude of the deflection is also a function of distance from the equator and velocity so the farther from the equator the object is the greater the deflection and the faster an object is moving the greater the deflection .these 'objects' can be anything from airplanes to birds to missiles to parcels of air . 565.the effect of the coriolis force for various latitudes . 566.we can see that coriolis force is maximum at high latitudes and minimum at the equator .thus the geostrophic wind is present at latitudes higher than about 15° north/south exemple 269 It is present at latitudes higher than about 15 degrees north/south.

Question 145-8 : What is the significance to aviation of breaks or steps in the tropopause ?

They indicate the position of strong upper winds

The 'breaks' or 'steps' in the tropopause are at the polar front and at the boundary between tropical and sub tropical air which is where the polar front and sub tropical jet streams are located . 595.this is the position of strong upper winds exemple 273 They indicate the position of strong upper winds.

Question 145-9 : Where are the westerlies to be expected ?

In the mid latitudes

Admin . 596.westerlies average latitude are 50°n and 50°s exemple 277 In the mid-latitudes.

Question 145-10 : Katabatic wind is ?

A flow of cold air down the slope of a mountain

Cqb15 september 2011 exemple 281 A flow of cold air down the slope of a mountain.

Question 145-11 : What is the average wind forecast for fl 300 between moscow and kiev . 378 ?

260/65

Admin . 636.close to moscow wind is from 270°/65 kt .close to kiev wind is from 250°/80 kt exemple 285 260/65.

Question 145-12 : Which of the following is correct regarding geostrophic wind ?

It blows parallel to straight equidistant isobars

The speed of a geostrophic wind calculated from the pressure gradient air density rotational velocity of the earth and latitude the calculation ignores the curvature of the wind's path a geostrophic wind is proportional to the pressure gradient or inversely proportional to the distance between the isobars . 568.winds exist because of horizontal and vertical pressure gradient so atmospheric motion can be deduced from isobaric surface charts etc if the horizontal pressure gradient force is exactly balanced in magnitude by coriolis effect accelerations of the air will be relatively small and a geostrophic wind will flow horizontally at a constant speed proportional to the isobaric spacing gradient perpendicular to the two opposing forces and parallel to straight isobars thus geostrophic wind speed is proportional to the pressure gradient the closer the isobars the higher will be geostrophic wind speed exemple 289 It blows parallel to straight equidistant isobars.

Question 145-13 : In this question the wind speed with straight isobars vst the wind speed around a high pressure system vhigh and the wind speed around a low pressure system vlow in the southern hemisphere are being compared while pressure gradient and latitude constant .which statement is correct ?

Vst < vhigh and vst > vlow

Admin .for same pressure gradient and same latitude the gradient wind is 'high round a high' vhigh and 'low round a low' vlow when compared to the geostrophic wind vst exemple 293 Vst < vhigh and vst > vlow.

Question 145-14 : Which of the following is correct regarding the wind speed in a jet stream in the northern hemisphere ?

With colder air to the left when looking downwind the wind speed increases with height while with the colder air to the right the wind speed decreases with height

The jet lies in the warm air above the frontal surface looking downwind the warm air tropopause lies to the right and above the core the cold air tropopause to the left and a litle lower than the core . 637.looking downwind the air in a jet core slowly rotates in a counterclockwise fashion .if you stand with your back to the wind and have cold air on your left you are below the core of the jet and wind speed will increase as you climb if you stand with your back to the wind and colder air the colder air from the warm tropopause which is colder than the air of the cold tropopause is on your right you are above the core of the jet and wind speed will decrease as you climb exemple 297 With colder air to the left when looking downwind, the wind speed increases with height, while with the colder air to the right the wind speed decreases with height.

Question 145-15 : Strongest clear air turbulence is to be expected ?

On the cold air side of the jet stream core

This question is similar to question 266 . in which zone of a polar front jet stream is the strongest cat to be expected on the polar air side of the core . 534.the strongest cat is in the warm tropical air but on the cold polar air side of the core exemple 301 On the cold air side of the jet stream core.

Question 145-16 : Which of the following statements is correct regarding the variation of wind with height ?

The wind normally veers during climb out through the first 2000 3000 feet in the northern hemisphere

exemple 305 The wind normally veers during climb out through the first 2000-3000 feet in the northern hemisphere.

Question 145-17 : On which latitudes can the coriolis force in practice be neglected for meteorological purposes ?

From 0 to about 10 degrees north and south

exemple 309 From 0 to about 10 degrees north and south.

Question 145-18 : Where is the wind speed of a polar front jet stream normally at its strongest ?

In the area between a trough and a ridge

Generally a trough of low pressure refers to region of low pressure within v shaped isobars it usually projects from a large and distant depression there is a sudden wind shift across the axis the axis is shown as broken lines on a weather chart of the trough which is associated with cloud and rain .a ridge of high pressure refers to a wedge shaped extension of a high pressure area and occurs between two depressions or lows wind shift is gradual across a ridge shown as zig zag line the ridge has a central area of light winds and clear skies .the ridge and trough are usually associated with different air masses warm and cold .this is where you get maximum temperature contrast and strongest thermal wind speed exemple 313 In the area between a trough and a ridge.

Question 145-19 : What is the icao qualifying term for the described intensity of turbulence .'conditions in which abrupt changes in aircraft attitude and/or altitude occur aircraft may be out of control for short periods' ?

Severe

Ecqb01 2013..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 exemple 317 Severe.

Question 145-20 : What wind direction will occur over the land at point e . 388 ?

West

Admin .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 we are in northern hemisphere from the way the fronts are positioned therefore at point e the wind is from the west exemple 321 West.

Question 145-21 : What wind direction will occur over the land at point b . 389 ?

Southwest

Admin .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 we are in northern hemisphere from the way the fronts are positioned therefore at point b the wind is from the southwest exemple 325 Southwest.

Question 145-22 : What kind of turbulence is caused by the friction of air flowing over the earth's surface ?

Mechanical turbulence

Ecqb01 june 2013 exemple 329 Mechanical turbulence.

Question 145-23 : Which of the following values corresponds to a ne wind ?

045°

exemple 333 045°.

Question 145-24 : Which of the following values corresponds to a se wind ?

135°

exemple 337 135°.

Question 145-25 : Which of the following values corresponds to a nw wind ?

315°

exemple 341 315°.

Question 145-26 : Which of the following values corresponds to a sw wind ?

225°

exemple 345 225°.

Question 145-27 : What is the average wind at fl 160 between zurich and rome . 397 ?

020°/50 kt

exemple 349 020°/50 kt.

Question 145-28 : Judging by the chart what windspeeds can you expect at fl 340 above rome . 398 ?

145 kt

exemple 353 145 kt.

Question 145-29 : Select from the map the average wind for the route frankfurt rome at fl 170 . 408 ?

230/40

Admin . 465.at fl180 you will find an average wind from 235° and a speed of 15 + 15 + 35 + 50 + 70 / 5 = 37 kt .closest answer is 230°/40 kt exemple 357 230/40.

Question 145-30 : At 40°n 70°w the forecast wind is . 416 ?

270°/95 kt

exemple 361 270°/95 kt.

Question 145-31 : A layer is conditionally unstable if the air ?

Is unstable for saturated air and stable for dry air

Admin .if the environmental lapse rate elr is more than 3°c/1000 ft dry adiabatic lapse rate the environment is unstable .if the environmental lapse rate elr is less than 1 8°c/1000 ft saturated adiabatic lapse rate the environment is stable .but .if the environmental lapse rate elr is more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability . stable if air is dry unsaturated .or. unstable if air is saturated exemple 365 Is unstable for saturated air and stable for dry air.

Question 145-32 : A parcel of unsaturated air is lifted to just below the condensation level and then returned to its original level what is the final temperature of the parcel of air ?

The same as the starting temperature

Admin .air can hold a certain amount of water depending on it's temperature warmer air can hold more water vapour than colder air .will climbing the parcel cools and hold less water vapour when the parcel comes back at its original level it will warm and come back in his original state exemple 369 The same as the starting temperature.

Question 145-33 : What characteristic is associated with a temperature inversion ?

Stability

exemple 373 Stability.

Question 145-34 : Absolute instability is said to exist whenever the environmental lapse rate ?

Exceeds the dry adiabatic lapse rate

Admin .if the environmental lapse rate elr is more than 3°c/1000 ft dry adiabatic lapse rate the environment is unstable .if the environmental lapse rate elr is less than 1 8°c/1000 ft saturated adiabatic lapse rate the environment is stable .but .if the environmental lapse rate elr is more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability . stable if air is dry unsaturated .or. unstable if air is saturated exemple 377 Exceeds the dry adiabatic lapse rate

Question 145-35 : Which of the following is a possible consequence of subsidence ?

An inversion over a large area with haze mist

Admin . 500.sinking air will dissipate cloud especially at lower levels and trap any pollution giving poor visibility exemple 381 An inversion over a large area with haze, mist.

Question 145-36 : What does 'dew point' mean ?

The temperature to which a mass of air must be cooled in order to reach saturation

exemple 385 The temperature to which a mass of air must be cooled in order to reach saturation.

Question 145-37 : Which of the following is the definition of relative humidity ?

Ratio between the actual mixing ratio and the saturation mixing ratio x 100

Admin .the most commonly used measure of humidity is relative humidity relative humidity can be simply defined as the amount of water in the air relative to the saturation amount the air can hold at a given temperature multiplied by 100 air with a relative humidity of 50% contains a half of the water vapor it could hold at a particular temperature . 501. concept of relative humidity exemple 389 Ratio between the actual mixing ratio and the saturation mixing ratio x 100

Question 145-38 : The relative humidity of a sample air mass is 50% .how is the relative humidity of this air mass influenced by changes of the amount of water vapour in it ?

It increases with increasing water vapour

Admin .the most commonly used measure of humidity is relative humidity relative humidity can be simply defined as the amount of water in the air relative to the saturation amount the air can hold at a given temperature multiplied by 100 air with a relative humidity of 50% contains a half of the water vapor it could hold at a particular temperature . 501. concept of relative humidity exemple 393 It increases with increasing water vapour.

Question 145-39 : Relative humidity ?

Changes when water vapour is added even though the temperature remains constant

Admin .the most commonly used measure of humidity is relative humidity relative humidity can be simply defined as the amount of water in the air relative to the saturation amount the air can hold at a given temperature multiplied by 100 air with a relative humidity of 50% contains a half of the water vapor it could hold at a particular temperature . 501. concept of relative humidity exemple 397 Changes when water vapour is added, even though the temperature remains constant.

Question 145-40 : How if at all is the relative humidity of an unsaturated air mass influenced by temperature changes ?

It decreases with increasing temperature

Admin .the most commonly used measure of humidity is relative humidity relative humidity can be simply defined as the amount of water in the air relative to the saturation amount the air can hold at a given temperature multiplied by 100 air with a relative humidity of 50% contains a half of the water vapor it could hold at a particular temperature . 501. concept of relative humidity exemple 401 It decreases with increasing temperature.


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