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MCQ > aircraft : The local hour angle of the mean sun at 1200 lmt is ?

Question 158-1 : 000° 090° 180° 270°

.in astronomy the hour angle is one of the coordinates used in the equatorial coordinate system for describing the position of a point on the celestial sphere the hour angle of a point is the angle between the half plane determined by the earth's axis and the zenith half of the meridian plane and the half plane determined by the earth's axis and the given point the angle is taken with minus sign if the point is eastward of the meridian plane and with the plus sign if the point is westward of the meridian plane.the hour angle is usually expressed in time units with 24 hours corresponding to 360 degrees.the hour angle of a point on the earth's surface is the angle through which the earth would turn to bring the meridian of the point directly under the sun the earth is rotating so this angular displacement represents time.so in observing the sun from earth the solar hour angle is an expression of time expressed in angular measurement most usually degrees from the solar noon.at solar noon at the observer's longitude on earth the hour angle is 0 000 degrees with the time before solar noon expressed as negative degrees and the local time after solar noon expressed as positive degrees.the hour angle is the angular displacement of the sun east or west of the local meridian due to rotation of the earth on its axis at 15° per hour with morning being negative and afternoon being positive .for example at 10 30 am the hour angle is 22 5° 15° per hour times 1 5 hours before noon exemple 258 000°.000°.

Location a is at 50°n 030°w and location b is at 50°s 030°w on 27th ?

Question 158-2 : Sunrise will be later at a than it is at b and sunset will be earlier at a than it is at b sunrise and sunset will be at the same time at a and b sunrise will be earlier at a than it is at b and sunset will be later at a than it is at b sunrise will be earlier at a than it is at b and sunset will be earlier at a than it is at b

.in winter the northern hemisphere is tilted away from the sun at this time the sun is not directly above us days will be shorter and nights longer. /com en/com061 552 jpg..in southern hemisphere this is summer and in northern hemisphere sunrise will be later and sunset will be earlier exemple 262 sunrise will be later at a than it is at b and sunset will be earlier at a than it is at b.sunrise will be later at a than it is at b and sunset will be earlier at a than it is at b.

An aircraft is flying a great circle track between waypoints number 4 45°00'n ?

Question 158-3 : Increased by less than 10° remained unchanged decreased by more than 10° decreased by less than 10°

.the aircraft is flying a great circle track which is on the pole side of the rhumb line 45°n . /com en/com061 555 jpg.from 040°w to 030°w rhumb line is 090° true track at waypoint number 4 is less than 090° .at 035°w we are at our highest latitude and at a true track of 090° .our true track to reach waypoint number 5 is now more than 090° our true track has increased exemple 266 increased by less than 10°.increased by less than 10°.

Given .variation is 6°w isogonic lines jan 2002 .average annual increase 10' ?

Question 158-4 : 6 5°w 5 5°w 5 5°e 6 3°w

.variation 6°w in 2002 increasing 10 minutes per year .2002 to 2005 = 3 years it is an increase of 30 minutes .6° + 30' = 6°30'w 6 5°w in 2005 exemple 270 6.5°w.6.5°w.

Position a = 56°00 0's 163°57 2'e .position b = 56°00 0's 171°47 4'w .for ?

Question 158-5 : Great circle direction at b is 080 7° great circle direction at b is 100 1° rhumb line distance is 1455 4 nm rhumb line distance is 1206 6 nm

. /com en/com061 565 jpg..great circle direction at b = 090° conversion angle 1/2 g sin lm .g change of longitude approximatively 24° .lm = mean latitude 56°.great circle direction at b = 090° 1/2 x 24° x sin56° .great circle direction at b = 080°.rhumb line distance from a to b = change of longitude x cos lat.rhumb line distance from a to b = 24 x 60 x cos 56°.rhumb line distance from a to b = 1440 x 0 559 = 805 nm exemple 274 great circle direction at b is 080.7°.great circle direction at b is 080.7°.

Position a = 30°00 0'n 175°23 2'w .position b = 30°00 0'n 173°48 1'e .for ?

Question 158-6 : Rhumb line distance is 578 nm great circle direction at a is 275 4° rhumb line distance is 648 7 nm great circle direction at b is 092 7°

. /com en/com061 566 jpg..great circle direction at a = 270° + conversion angle 1/2 g sin lm .great circle direction at b = 270° + conversion angle 1/2 g sin lm .g change of longitude approximatively 11° .lm = mean latitude 30°.conversion angle = 1/2 x 11° x sin30°.conversion angle = 2 75° 3° .great circle direction at a = 270° + 3° = 273°.great circle direction at b = 270° 3° = 267°..rhumb line distance from a to b = change of longitude x cos lat.rhumb line distance from a to b = 11 x 60 x cos 30°.rhumb line distance from a to b = 660 x 0 866 = 572 nm close to 578 nm exemple 278 rhumb line distance is 578 nm.rhumb line distance is 578 nm.

The first law of kepler states ?

Question 158-7 : Planets move in elliptic orbits with the sun in one of the foci planets move around the sun in a circular orbit all planets orbit around the sun at the same speed the angular speed of the planet in the orbit around the sun is constant

exemple 282 planets move in elliptic orbits with the sun in one of the foci.planets move in elliptic orbits with the sun in one of the foci.

What is meant by 'aphelion' ?

Question 158-8 : The point of the earth's orbit furthest away from the sun the point of the sun's orbit furthest away from the earth the point of the earth's orbit closest to the sun the point of the sun's orbit closest to the earth

. 2477.the aphelion is the point in the orbit of a planet or comet where it is farthest from the sun exemple 286 the point of the earth's orbit furthest away from the sun.the point of the earth's orbit furthest away from the sun.

Which statement about meridians is correct ?

Question 158-9 : A meridian and its anti meridian form a complete great circle the plane of a meridian is parallel to the equator all meridians are parallel to the meridian of greenwich a meridian is a complete great circle of 360°

exemple 290 a meridian and its anti-meridian form a complete great circle.a meridian and its anti-meridian form a complete great circle.

A rhumb line from a position 86°n 30°w has an initial track of 085°t is it ?

Question 158-10 : A spiral to the north pole a small circle north of 86°n initially north 86°n and 180° later south of 86°n a random northerly track to the pole

. /com en/com061 664 jpg..when following a rhumb line track you fly via a spiral to the north or south pole except for track 000° 090° 180° and 270° exemple 294 a spiral to the north pole.a spiral to the north pole.

A great circle track crosses the equator at 30°w has an initial track of ?

Question 158-11 : 55°n 060°e 35°n 150°w 55°s 060°w 35°s 150°e

.a great circle divides earth in two equal hemispheres .the equator is a great circle meridians of longitude that cross over the north and south poles are also great circles .on this picture great circles are in black purple equator and yellow meridians. /com en/com061 611 jpg..our great circle intersects the equator in 030°w with a great circle direction of 035° t his antipodal location on the equator will be 030° w 180° = 150° e.our airplane will reach his highest latitude at halfway 030° w 090° = 060° e.we are climbing on a north track we are in northen hemisphere only one answer remains possible exemple 298 55°n 060°e.55°n 060°e.

The latitude of the tropic of capricorn is ?

Question 158-12 : 23 5°s 23 5°n 66 5°n 66 5°s

exemple 302 23,5°s.23,5°s.

Which statement is true ?

Question 158-13 : The declination of the sun and the latitude of the observer will affect the duration of civil twilight the duration of the civil twilight on 21st of march and on 23rd of september is equal at all places on earth independent of latitude only the declination of the sun will affect the duration of civil twilight civil twilight at the equator lasts longer than at 60°n or 60°s because the radius of the equator is larger than the radius of the 60°parallel

exemple 306 the declination of the sun and the latitude of the observer will affect the duration of civil twilight.the declination of the sun and the latitude of the observer will affect the duration of civil twilight.

At 00h00 local mean time of an observer ?

Question 158-14 : The mean sun is in transit with the observer's anti meridian the apparent sun is in transit with the observer's anti meridian the mean sun is in transit with the observer's meridian the apparent sun is in transit with the observer's meridian

.local mean time is solar time as measured by the position of the mean sun with respect to an observer's local meridian local mean time differs continuously with the observer's longitude and is not standardized over a time zone however a day as measured by local mean time does not vary in length throughout the year it is always 24 hours and at midnight 00h00 it will be on the observer's anti meridian exemple 310 the mean sun is in transit with the observer's anti-meridian.the mean sun is in transit with the observer's anti-meridian.

Kepler's second law states that ?

Question 158-15 : The radius vector sun earth sweeps out equal areas in equal time the radius vector sun earth moves at constant angular speed the length of the radius vector sun earth is directly proportional to the square root of its angular speed the area swept out by the radius vector sun earth per hour increases with increasing length of the radius vector

.kepler's second law states an imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time .the animation below depicts the elliptical orbit of a planet about the sun . 2040..the dot pattern shows that as the planet is closest the sun the planet is moving fastest and as the planet is farthest from the sun it is moving slowest nonetheless the imaginary line joining the center of the planet to the center of the sun sweeps out the same amount of area in each equal interval of time . 2041 exemple 314 the radius vector sun-earth sweeps out equal areas in equal time.the radius vector sun-earth sweeps out equal areas in equal time.

Consider the positions 00°n/s 000°e/w and 00°n/s 180°e/w on the ellipsoid ?

Question 158-16 : The route via the north pole is shorter than the route along the equator the route via the equator is shorter than the route via the south pole the route via either pole and the route via the equator are of equal length the route via the south pole is shorter than the route via the north pole

.since earth shape is an ellipsoid the distance from position a 00°n/s 000°e/w to b 00°n/s 180°e/w both located on the equator will be shorter via the poles. /com en/com061 587 jpg. exemple 318 the route via the north pole is shorter than the route along the equator.the route via the north pole is shorter than the route along the equator.

The sr/ss sunrise/sunset table for the 23rd of february at latitude 40°n gives ?

Question 158-17 : The sun rises at 64°w the sun rises at 79°w the sun sets at 86°e the sun sets at 116°e

.sr and ss are given in utc so we need to know first the central european time in utc.when it is 11 00 utc it's 12 00 local time in central europe utc+1..now in central europe the sun rises at 06h44 utc so 4h and 16 minutes later at 11 00utc where does the sun is rising.answer we must be near the north american and canadian border close to the coast..4h and 16 minutes = 256 minutes...what is the speed of the trace of the sunrise on the ground..1440 minutes per day 24h per day 360° to cover for a complete turn of the sun around the earth so 1440/360 = 4 minutes par degree...256/4 = 64°...when it is 11 00 utc the sun rises at 64° west of our position exemple 322 the sun rises at 64°w.the sun rises at 64°w.

An aircraft follows a great circle in the northern hemisphere at a certain ?

Question 158-18 : Track angle will decrease and the latitude will decrease track angle will increase and the latitude will decrease track angle will decrease and the latitude will increase track angle will increase and the latitude will increase

. /com en/com061 594 jpg..following a great circle track in the northern hemisphere your heading will decrease track angle will decrease and the latitude will decrease too exemple 326 track angle will decrease and the latitude will decrease.track angle will decrease and the latitude will decrease.

On an oblate spheroid representing the earth's shape ?

Question 158-19 : 1 minute of arc along the equator measures a greater distance than 1 minute of arc along the meridian at a latitude of 45°n/s 1 minute of arc along the equator measures the same distance as 1 minute of arc along the meridian at a latitude of 45°n/s 1 minute of arc along the meridian at low latitudes measures a greater distance than 1 minute of arc along the meridian at high latitudes 1 minute of arc along the meridian at 0°n/s measures the same distance as 1 minute of arc at 90°n/s

.the earth is a tad wider than it is tall giving it a slight bulge at the equator this shape is known as an ellipsoid the diameter from the north pole to the south pole the shortest diameter is approximately 6860 nm and the equatorial diameter the longest diameter is approximately 6883 nm .the polar circumference is 21554 nm each minute of arc being equal to 0 998 nm .the equatorial circumference is 21626 nm each minute of arc being equal to 1 001 nm exemple 330 1 minute of arc along the equator measures a greater distance than 1 minute of arc along the meridian at a latitude of 45°n/s.1 minute of arc along the equator measures a greater distance than 1 minute of arc along the meridian at a latitude of 45°n/s.

Given .a 56°n 145°e .b 57°n 165°w .what is the difference in longitude ?

Question 158-20 : 050° 020° 130° 001°

.we only want to know the difference in longitude between a and b is 50° not the distance between a and b so latitudes are irrelevant.from a longitude to reach the anti meridian 180°e/w we have 35° of longitude and then to reach b longitude we have 15° of longitude .35° + 15° = 50° exemple 334 050°.050°.

What is the duration of morning civil twilight at 66°48'n 095°26'w on 27th of ?

Question 158-21 : 01h 13m 08h 14m 09h 27m 01h 02m

. 1809.at 67°n on january 26th the duration of morning civil twilight is 1h34 min.we are looking for january 27th .you can continue to interpolate with january 28th but if you look at the sunrise difference time between 26th and 28th at 66°n you gain 11 minutes now for the morning civil twilight between 26th and 28th at 66°n you gain 7 minutes .so for january 27 th 1h33 minutes sounds good exemple 338 01h 13m.01h 13m.

The gmt of morning civil twilight at 66°48'n 095°26'w on 27th of january is. ?

Question 158-22 : 1436 gmt 0927 gmt 1541 gmt 0814 gmt

.the answers are all in gmt so take the time from the annex and adjust for longitude at 15°/h .95°26' / 15 = 6h 22min.as the location is west of the prime meridian the answer must be later in the day reference to gmt .0814 + 6 hrs 22 = 1436 gmt. notice 0814 is calculated by interpolation exemple 342 1436 gmt.1436 gmt.

The gmt of sunrise at 66°48'n 095°26'w on 27th of january is. err a 061 606 ?

Question 158-23 : 1549 gmt 0927 gmt 1541 gmt 0814 gmt

.sunrise at 66°48'n 095°26'w on 27th of january. /com en/com061 606 jpg...interpolation between 26th and 29th january . difference at 68n is 13 minutes for 4 days so for one day is 3 25 minutes . difference at 66n is 11 minutes for 4 days so for one day is 2 75 minutes.we are looking for 66°48'n 3 minutes is a good deal .09h39 66°n to 9h45 68°n on january 26th at 66°48' it will be 09h32 and 09h49 on january 27th..now convert local mean time lmt at longitude 095°26'w .95 4° x 4 minutes = 381 6 minutes..381 6 minutes = 6 36 hours = 6 h 22 minutes.09h49 + 6h42 = 15h51 utc exemple 346 1549 gmt1549 gmt

The latitude of the tropic of cancer is ?

Question 158-24 : 23 5°n 23 5°s 66 5°n 66 5°s

exemple 350 23,5°n.23,5°n.

Position a is 31°00's 176°17'w .rhumb line track t from a to b is 270° ?

Question 158-25 : 31°00's 168°58'e 31°00's 161°32'w 31°00's 173°24'w 31°00's 173°24'e

.difference between the great circle track and rhumb line track is conversion angle.conversion angle = 270° 266 2° = 3 8°..1/2g sin 31° = 3 8°.g change of longitude.1/2g = 3 8° / sin 31°.1/2g = 7 38°.g = 14 76°...176°17'w + 14 76° or 14°45' = 168°58'est exemple 354 (31°00's, 168°58'e)(31°00's, 168°58'e)

An aircraft departs from schiphol airport and flies to santa cruz in bolivia ?

Question 158-26 : 21h05 10th nov 22h05 10th nov 07h05 11th nov 09h05 11th nov

Cmarzocchini .i only did 06h45 utc off blocks + 00h45 + 09h40 + 00h45 + 02h40 + 06h30 = 26h05 .in santa cruz bolivia utc +5 so 26h05 5h = 21h05 same day exemple 358 21h05 10th nov.21h05 10th nov.

Two places on the parallel of 47°s lie 757 8 km apart calculate the difference ?

Question 158-27 : 10°00' 4°39' 9°19' 4°51'

.first convert km in nm.757 8 km / 1 852 = 409 nm...distance = change of longitude x cos of latitude..409 nm = change of longitude x cos 47°..change of longitude = 409 / cos 47° = 600 minutes..600 / 60 min per degree = 10° exemple 362 10°00'.10°00'.

In a sunrise/sunset table given for the 28th of june at a certain latitude ?

Question 158-28 : 60°n 80°n 55°s 00° n/s

.it must be in the northern hemisphere because it's summer and 28th of june it's quite a long period of daylight but at 80 degrees north you have mid summer night this is where the sun never goes below the horizon i think that's why the answer is 60 degrees north. .absolutly we are close to the longest day during summer time in the northern hemisphere .furthermore above 66 5°n in summer it is permanent daylight exemple 366 60°n.60°n.

On the earth's ellipsoid one degree of latitude near the equator is ?

Question 158-29 : Less than 60 nm 60 nm more than 60 nm more than 60 nm but less than 61 nm

.at the equator one degree of latitude = 110 57 km or 59 7 nm.at 50°n or 50°s one degree of latitude = 111 23 km or 60 05 nm.at the poles one degree of latitude = 111 69 km or 60 3 nm.the geoid is an ellipsoidal form so a degree of latitude centered on the equator is not the same length as one degree of longitude along the equator the difference is small enough to ignore for many applications exemple 370 less than 60 nm.less than 60 nm.

With an increase in magnetic latitude there will be a decrease in the ?

Question 158-30 : Directive force angle of dip vertical component of the earth's magnetic field total magnetic force of the earth's magnetic field

.the directive force is the horizontal component of the earth's magnetic field the horizontal component of the earth's magnetic field is stronger at magnetic equator and very weak at the magnetic poles .thus if you are heading to the magnetic poles your latitude is increasing there will be a decrease in the directive force exemple 374 directive force.directive force.

Which statement about the duration of daylight is true ?

Question 158-31 : Close to the equinoxes the influence of latitude on the duration of daylight is at its smallest close to the solstices the influence of latitude on the duration of daylight is at its smallest on september 10th the duration of daylight is longer on the southern hemisphere than on the northern hemisphere in summer the length of the period of daylight decreases with increasing latitude

exemple 378 close to the equinoxes the influence of latitude on the duration of daylight is at its smallest.close to the equinoxes the influence of latitude on the duration of daylight is at its smallest.

Which figure in the appendix represents the geocentric latitude of position p ?

Question 158-32 : Figure b figure a figure c figure d

.geocentric latitude is measured from the centre of the ellipsoid geodetic or geographic latitude which is what is normally measured is the angle between the plane of the equator and the line which is normal to the ellipsoid at the point of interest unlike geocentric latitude this line does not typically pass through the centre of the ellipsoid whenever the unqualified term latitude is used it will normally mean the geographic latitude. /com en/com061 662 jpg..on the wgs84 ellipsoid the length of a degree of latitude increases from 110 574 km at the equator to 111 694 km at the poles geographic and geocentric latitudes can differ by as much as 12 minutes of arc an amount equivalent to a distance of more than 30 km on the ground exemple 382 figure b.figure b.

Which figure in the appendix represents the geographic latitude of position p ?

Question 158-33 : Figure a figure b figure c figure d

.geographic latitude is define as the angle between the plane of the equator and the local plumb line on the ellipsoid .on figure a you can notice that the local plumb line intersects the plane of the equator not in the center of the sphere because earth is an ellipsoid exemple 386 figure a.figure a.

The long term periodic change in the earth's magnetic field ?

Question 158-34 : Is reflected in the slow movement of the magnetic poles is caused by sunspot activity is caused by the westerly movement of the geographic north pole affects mainly the compass deviation

Feedback pour traduction fr 'a quoi est dûe la variation du champ magnétique terrestre au déplacement lent et progressif des pôles magnétiques' exemple 390 is reflected in the slow movement of the magnetic poles.is reflected in the slow movement of the magnetic poles.

The horizontal component of the earth's magnetic field ?

Question 158-35 : Is very small close to the magnetic poles is maximum at the magnetic poles is minimum at the magnetic equator increases with an increase of the magnetic latitude

. /com en/com061 593 jpg..diagrammatic representation of the earth's magnetic field illustrating how field lines represented by arrows intersect the earth's surface and how inclination angle the angle formed between the field lines and the earth varies with latitude at the magnetic equator the curving line across the earth field lines are parallel to the earth's surface the field lines become progressively steeper as one travels north toward the magnetic pole where the field lines are directed straight down into the earth and the inclination angle is 90° . near the magnetic pole the horizontal component of the earth's magnetic field is too small to permit the use of a magnetic compass exemple 394 is very small close to the magnetic poles.is very small close to the magnetic poles.

An observer is situated on the parallel of 23 5°s which statement about the ?

Question 158-36 : It passes through the zenith once a year around december 22nd it passes through the zenith twice a year around june 21st and december 22nd it passes through the zenith once a year around march 21st it passes through the zenith twice a year around march 21st and september 23rd

.the axis of the earth is tilted 23 5° degrees from 'vertical' this causes the northern hemisphere to be tilted toward the sun during half the year and tilted away from the sun the other half of the year . 2475.the sun is vertical at the zenith at 23 5°s for the solstice around december 22nd.you can see on this picture the sun's rays vertical to the surface at 23 5°s . 2028 exemple 398 it passes through the zenith once a year around december 22nd.it passes through the zenith once a year around december 22nd.

At 54°n 020°w the sun rises on november 28th at 09 01 utc .at 44°n 020°w ?

Question 158-37 : Earlier since the latter position lies further south later since the latter position lies further south also at 09 01 utc since both positions are situated on the same meridian at 07 41 lmt

.on november 28th we are approaching winter solstice 21 22 december . 1781.the axis of the earth is tilted 23 5° degrees from 'vertical' this causes the northern hemisphere to be tilted toward the sun during half the year and tilted away from the sun the other half of the year .after autumnal equinox northern hemisphere is tilted away and as you can see on this picture position '44°n 020°w' will see the sun rising earlier than the position '54°n 020°w' exemple 402 earlier since the latter position lies further south.earlier since the latter position lies further south.

What is the correct definition of latitude of a position on the earth ?

Question 158-38 : Latitude is the angle between the plane of the equator and the line from the centre of the earth to the position latitude is the angle between the earth's rotational axis and the line from the centre of the earth to the position latitude is the angle between the plane of the prime meridian and the plane of the meridian of the position latitude is the angle between the plane of the ecliptic and the parallel of the position

exemple 406 latitude is the angle between the plane of the equator and the line from the centre of the earth to the position.latitude is the angle between the plane of the equator and the line from the centre of the earth to the position.

When proceeding on a given date along a parallel towards the east the moment of ?

Question 158-39 : Utc lmt standard time lat local apparent time

exemple 410 utcutc

The maximum difference in distance when proceeding along the great circle ?

Question 158-40 : On east west tracks at high latitudes on north south tracks at high latitudes on east west tracks at low latitudes on north south tracks at low latitudes

/com en/com061 674 jpg..green great circle track.red rhumb line..right answer is east west track at high latitudes but west east track at high latitudes will also be right exemple 414 on east-west tracks at high latitudes.on east-west tracks at high latitudes.

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