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Question 173-1 : Which figure in the appendix represents the geographic latitude of position p which is situated above the surface of the ellipsoid . err a 061 663 ? [ Practice protocol ]
Figure a
.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
Question 173-2 : The long term periodic change in the earth's magnetic field ?
Is reflected in the slow movement of the magnetic poles
Feedback pour traduction fr 'a quoi est dûe la variation du champ magnétique terrestre au déplacement lent et progressif des pôles magnétiques'
Question 173-3 : The horizontal component of the earth's magnetic field ?
Is very small close to the magnetic poles
. /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
Question 173-4 : An observer is situated on the parallel of 23 5°s which statement about the passage of the apparent sun in relation to this position is correct ?
It passes through the zenith once a year around december 22nd
Admin .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
Question 173-5 : At 54°n 020°w the sun rises on november 28th at 09 01 utc .at 44°n 020°w the sun will rise ?
Earlier since the latter position lies further south
Admin .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'
Question 173-6 : What is the correct definition of latitude of a position on the earth ?
Latitude is the angle between the plane of the equator and the line from the centre of the earth to the position
Question 173-7 : When proceeding on a given date along a parallel towards the east the moment of sunrise will occur one hour earlier every 15° difference in longitude when it is expressed in ?
Utc
Question 173-8 : The maximum difference in distance when proceeding along the great circle between two positions in stead of the rhumb line will occur ?
On east west tracks at high latitudes
Img /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
Question 173-9 : Geodetic latitude and geocentric latitude coincide ?
At the poles and on the equator
Admin .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 . 1785.the relation between the geodetic latitude and the geocentric latitude is . 1361.the geodetic and geocentric latitudes are equal at the equator and poles the value of the squared eccentricity is approximately 0 007 depending on the choice of ellipsoid and the maximum difference between geocentric and geodetic latitude is approximately 11 5 minutes of arc at a geodetic latitude of 45°6'
Question 173-10 : The time difference in local mean time between sunset at positions a 50°n 120°e and b 50°s 120°e on the 21st of november is ?
Some hours and the sun rises earlier in b than in a
.on the 21st of november it's winter in northern hemisphere .timing of sunsets and sunrises are driven by the axial tilt of earth in the summertime the days get longer and sunsets occur later .thus since it is summer in southern hemisphere the sun will rise earlier in b than a and the sun will disappear earlier in a than in b
Question 173-11 : Which statement about standard time is true ?
Standard time is determined by the government of the appropriate state and does not necessarily follow the borders of 15° wide longitude zones
.the local time at 125°w is utc 8h40m the standard time is determined by the government of the appropriate state and does not necessarily follow the borders of 15° wide longitude zones
Question 173-12 : Which statement is correct about the apparent solar day ?
The apparent solar day is the period between two successive transits of the true sun through the same meridian
Admin .the solar day or the time corresponding to one rotation of the earth with respect to the direction of the sun is the most natural unit of time for ordinary purposes if time was regulated by stars sidereal noon would occur at night during half the year for obvious reasons this would not be a satisfactory condition also to begin the solar day when the sun crosses the observer's meridian would result in confusion so to keep an orderly scheme of things we start the solar day when the sun crosses the lower meridian of the observer the instant of time when the sun is on the lower branch of the observer's meridian is defined as solar midnight when the sun crosses the upper branch of the observer's meridian it is solar noon at the observer's location . the period between two successive transits of the true sun through the same meridian is called an apparent solar day .the time indicated by the position of the actual true sun is called apparent solar time .the mean solar day is an invariable unit of time it is based on a fictitious or mean sun which is imagined to move at a uniform rate in its apparent path about the earth
Question 173-13 : Which statement regarding the apparent sun and the mean sun is correct ?
The apparent sun is the visible sun the mean sun is a fictitious sun
.apparent sun 'apparent solar time' or 'true solar time' is given by the daily apparent motion of the true or observed sun it is based on the apparent solar day which is the interval between two successive returns of the sun to the local meridian .the mean sun is imaginary sun moving along the celestial equator at a constant rate and completing its annual course in the same time as the sun takes to move round the ecliptic at a varying rate it is used in the measurement of mean solar time .mean solar time conceptually is the hour angle of the fictitious mean sun the duration of daylight varies during the year the length of a mean solar day is nearly constant unlike that of an apparent solar day
Question 173-14 : The declination of the sun is defined as ?
The angular distance of the sun north or south of the celestial equator
. /com en/com061 682 gif.directly above the equator of the earth we find the celestial equator in the sky .declination of the sun is the angular distance of the sun north or south of the celestial equator . /com en/com061 682a jpg.the earth's equator is tilted 23 5 degrees with respect to the plane of the earth's orbit around the sun so at various times during the year as the earth orbits the sun declination varies from 23 5 degrees north to 23 5 degrees south . /com en/com061 682b jpg.this gives rise to the seasons around december 21 the northern hemisphere of the earth is tilted 23 5 degrees away from the sun which is the winter solstice for the northern hemisphere and the summer solstice for the southern hemisphere around june 21 the southern hemisphere is tilted 23 5 degrees away from the sun which is the summer solstice for the northern hemisphere and winter solstice for the southern hemisphere on march 21 and september 21 are the fall and spring equinoxes when the sun is passing directly over the equator note that the tropics of cancer and capricorn mark the maximum declination of the sun in each hemisphere
Question 173-15 : The time interval between sunrise and sunset is dependent on ?
The declination of the sun and the latitude of the observer
.depending on your location the times of sunrise and sunset and the length of the daylight period varies in a sine wave pattern .the axis of spin of the earth is not vertical to the plane between the earth and the sun .even though the earth spins on that axis and rotates around the sun the tilt of the axis never changes because of this the northern and southern hemispheres are exposed to more or less sunlight at different times .as a result when the top of the earth is in a position where it is closer to the sun the sun's light rays strike well above the equator resulting in summer and longer days . /com en/com061 684 gif.when it is summer in the northern hemisphere it is winter in the southern hemisphere
Question 173-16 : The definition of true north for any observer is ?
The direction of the observer's meridian to the north pole
.true north may in practical terms be magnetic north corrected for local variation but that is not the definition the definition is 'the direction from the observer to the geographic north pole along the local meridian'
Question 173-17 : A definition of a magnetic track angle is ?
The direction of a line referenced to magnetic north
.magnetic track angle the angle measured in a clockwise direction between the track and magnetic north . the direction of the longitudinal axis of an aircraft referenced to magnetic north is the magnetic heading of the aircraft . the direction of the longitudinal axis of an aircraft referenced to compass north is the compass heading of the aircraft
Question 173-18 : The main reason for the occurrence of seasons on earth is ?
The inclination of the earth axis with regard to the plane of the ecliptic
Admin .the axis of the earth is currently 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 this is the mechanism responsible for the seasons . 2475.the ecliptic is the apparent path of sun around the earth
Question 173-19 : The length of the apparent solar day varies continuously throughout a year this is caused by ?
The tilt of the earth's axis and the elliptical orbit of the earth around the sun
Question 173-20 : Which definition of the equator is correct ?
The equator is a greatcircle with its plane perpendicular to the earth rotational axis
Question 173-21 : The direction 'magnetic north' at a position on the earth is ?
The direction of the horizontal component of the earth's magnetic field at that position
Admin .earth's magnetic field has various distortions may not be aligned with the great circle to the magnetic pole .a freely suspended magnet will align itself with the earth's magnetic field assuming no other fields influencing the magnet the total field force t is resolved into a horizontal component force h and a vertical component force z we try to keep the magnets in a direct reading compass as close as possible to the local horizontal by suspending them below the pivot point and in some cases by adding weights to bias them for the northern hemisphere or the southern hemisphere the alignment of the horizontal component of the earth's field is therefore the azimuthal alignment of magnetic north
Question 173-22 : In which statement is the 'mean sun' best described ?
The mean sun is a fictitious sun coinciding each year with the apparent sun at the spring equinox and travelling along the celestial equator at uniform speed
.easa definition . mean sun the mean sun is conceived to move eastward along the celestial equator at a rate that provides a uniform measure of time equal to the average time reckoned from the true sun .collins english dictionary . mean sun an imaginary sun moving along the celestial equator at a constant rate and completing its annual course in the same time as the sun takes to move round the ecliptic at a varying rate it is used in the measurement of mean solar time
Question 173-23 : Which statement about the orbit of the earth is correct ?
The orbit of the earth around the sun is an ellipse with the sun at one of the foci
Question 173-24 : The reason that the solar day lasts longer than the sidereal day is that ?
Both the direction of rotation of the earth around its axis and its orbital rotation around the sun are the same
A solar day is the length of time between two successive passes of the sun across the same spot in the sky e g crossing the meridian overhead that time period is on average 24 00 00 hours or one mean solar day .a sidereal day is the length of time between two successive passes of the fixed stars across the sky that time period is 23 56 04 or one sidereal day .the difference occurs because over the course of a year the earth does one revolution or 'lap' around the sun so that there must be one less solar day 365 25 per year than there are sidereal days 366 25 spread over the year comes to a difference of about four minutes each day .vdo930
Question 173-25 : Which definition describes best the notion 'poles' ?
The poles are the points of intersection between the earth's axis and the surface of the earth
.the north and south poles are at either end of the earth's axis around which the earth rotates
Question 173-26 : 'a' latitude is 00°n/s .'b' is located at 33°n 101°e .true track great circle from 'a' to 'b' at 'b' is 090° .the initial true track of the great circle at 'a' is ?
057°
Admin . 2481.it's a great circle at 'b' latitude is 33°n departure angle at the equator = 90° 'b' latitude = 057°
Question 173-27 : Given two positions .a 56°s 010°w and b 56°s 030°w .which statement is true ?
The departure between a and b is more than great circle distance between a and b
Admin .great circle is the shortest distance between two points . 1462.easa notice distance along a parallel of latitude is also known as departure
Question 173-28 : Standard time for same areas is listed in the air almanac as utc +13 instead of 11 .the reason for this is ?
Keeping the same date as the political and or economical entity to which they belong
Question 173-29 : Polar circles are line of latitude at ?
67° n/s
Admin .polar circles are two parallels of latitude each at a distance from a pole of the earth equal to about 23 degrees 27 minutes it forms the boundary between the north temperate and north frigid zones
Question 173-30 : Mu'a tonga islands is situated at 21°11's 175°07'w .in the air almanac the standard time of tonga islands is listed as utc +13 .for august 21st the sunrise table in the air almanac shows .20°s 06 18 lmt.30°s 06 28 lmt.what is the standard time of sunrise at mu'a ?
06 59 on august 22nd
Admin .sunrise at 20°s = 06 18 lmt on 21 august.sunrise at 30°s = 06 28 lmt on 21 august.sunrise at 21°s will be 06 19 lmt .conversion to utc .175°07' ==> 11h40 min 175 / 15°/h .06h39 + 11h40 = 17h59 utc .conversion to standard time .17h59 + 13 = 30h59 st .30h59 24h = 06 59 on august 22nd
Question 173-31 : Position 'elephant point' is situated at 58°00'n 135°30'w .standard time for this location is listed in the air almanac as utc 8h .if sunset occurs at 00 57 utc on 21st january what is the time of sunset in lmt ?
15 55 on january 20th
.the conversion factor between lmt and utc is arc change of longitude converted to time .135°30' ==> 9h02 min 135 5 / 15°/h .00h57 9h02 = 15h55 lmt the day before january 20th
Question 173-32 : The direction of the earth's rotation on its axis is such that ?
Observed from the point above the north pole the rotation is counterclockwise
.the earth is described as rotating from west to east if you were looking down on the north pole from space the earth would be seen to be rotating anti clockwise this is why the sun appears to rise in the east and set in the west to an observer standing on the ground the earth then rotates around the sun in an anti clockwise direction on an elliptical path
Question 173-33 : The sun's declination is ?
The sun's position relative to the plane of equator
Question 173-34 : The sun's declination is on a particular day 12°s midnight sun may this day be observed ?
South of 78°s
Question 173-35 : The term 'sidereal' is used ?
To describe a situation or relationship concerning the stars
Question 173-36 : The mean sun ?
Moves with constant speed along the celestial equator
Question 173-37 : In its path around the sun the axis of the earth has an inclination ?
Of 66°33' with the plane of the path
Juliarmengol98 2018 02 15 as far as i understand 0 to 23º27' 23 5º would be correct if the question asked for the latitudes the sun would be directly overhead at one point during its path .as it asks for the earth's axis inclination 23 5º in relation to the plane of the earth like the equator 90º the relative angle inclination between them would be of 66º 33'~
Question 173-38 : As seen from an observer on the surface of the earth ?
The apparent sun is always in the plane of the ecliptic
.apparent sun 'apparent solar time' or 'true solar time' is given by the daily apparent motion of the true or observed sun it is based on the apparent solar day which is the interval between two successive returns of the sun to the local meridian .the plane of the ecliptic is inclined to the plane of the equator at an angle of approximately 23 5° . /com en/com061 712 jpg.from an observer on the surface of the earth the apparent sun is always in the plane of the ecliptic
Question 173-39 : The time it takes for the earth to complete one orbit around the sun is ?
365 days 5 hours 48 minutes and 45 seconds
Question 173-40 : When the sun's declination is northerly ?
The daylight period is shorter in the southern hemisphere than the northern
~
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