Air Navigation: The art of going from place A to B, through
the medium of air, safely.
Solar System and the Earth: Our solar system comprises of nine planets revolving around the sun at different distances. The closest planet to the sun is ‘Mercury’, followed by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune; with Pluto being the farthest from the Sun. Mercury completes one orbit around the Sun in about 88 days and Pluto in about 249 years.
Sphere: A sphere is a solid body bounded by a surface upon which all points are equidistant from the centre. Radius of all points on the surface of the sphere is the same.
The Earth
The Earth revolves around the Sun in an elliptical orbit, taking about 365¼ days to complete one orbit. It also rotates around its own axis, from West to East, once in approx 24 hours. Its axis of rotation is tilted at an angle of 66.5° to the elliptical plane of its revolution around the sun. This causes seasons. Its rotation about its own axis causes day and night.
The earth is an oblate spheroid – i.e. not a perfect sphere, but can be considered to be a perfect sphere for all practical purposes. It is flattened at the poles, with the equatorial diameter (12748.6 kms) being 43 kms more than the polar diameter (12705.6 kms). The flattening at the poles is called Compression.
Compression Ratio = 43/12748.6 = 1/ 296.5
Poles
The points of intersection of the axis of rotation of the earth and the earth’s surface are called poles – North and South pole. The names have been arbitrarily selected. The North pole is the pole about which the earth rotates anti-clockwise; and rotates clockwise about the S-pole, when viewed from above the respective pole.
Great Circle (GC)
It is a circle on the surface of the sphere (earth) whose radius and centre are same as that of the earth. It is the largest circle that can be drawn on the surface, and thus its name. A GC has certain properties. These are as follows: -
• It divides the sphere into two equal halves.
• It has the same radius and centre as the sphere.
• Only one GC can be drawn through two points not diametrically opposite.
• Any number of GCs can be drawn through two diametrically opposite (anti-podal) points.
• The shortest distance between two places is the smaller arc of the GC drawn through them.
Small Circle
Any circle on the surface of the sphere (earth) that is not a GC is a small circle. A small circle’s radius and centre would thus not be the same as that of the earth.
Equator
Equator is a GC whose plane is at right angles to the axis of rotation of the earth, and it divides the earth into two equal halves – the Northern and Southern hemispheres. It is the datum for measuring latitude. Thus latitude is either North or South of the equator. Also, equator itself is 0° latitude.
Meridians
Meridians are semi GCs joining from pole to pole. Thus every GC passing through the poles comprises of a meridian and its anti-meridian. All meridians cut the equator at 90°.
Rhumb Line (RL)
A RL is a regularly curved line on the surface of the earth that cuts all meridians at the same angle. It can also be called as the line of constant true direction. So, aircraft flying constant true track would be flying RL track. Other points of interest are: -
• Only one RL can be drawn through any 2 points.
• RL is not the shortest distance between 2 points, but is convenient to fly.
• All meridians and equator are the only examples of GC that are also RL.
• All parallels of latitude and meridians intersect with each other at 90°. So all parallels of latitude are RLs.
Prime Meridian (PM)
The meridian passing through Greenwich Village (close to London) is called the Prime Meridian, and is the datum for measuring longitude. Thus longitude is either East or West of the Prime meridian. Also, the longitude of the PM is 0°.
Parallel of Latitude
Parallels of latitude are small circles whose plane are parallel to the plane of the equator, and cut all meridians at 90°.
Graticule
This network of parallels of latitude and the meridians drawn on the surface of the earth is called a graticule.
Latitude
Latitude of a place is the arc of the meridian between the equator and the parallel of latitude on which the place lies. It is measured in degrees, minutes, seconds North or South of the equator. (1° = 60’ and 1’ = 60”). Latitude is the angular distance along the meridian.
What is the latitude of the North pole? Why? Can you explain.
Longitude
Longitude of a place is the smaller arc of the equator measured between the PM and the meridian passing through the place. It is measured in degrees, minutes and seconds East or West of the PM. Longitude is the angular distance along the equator.
Defining Position on the Earth
Position on the earth can be defined in any of the following manners: -
• Place Name
• Bearing and distance from known place
• Latitude/ Longitude
Conventionally a place is defined in lat/ long, by the latitude first followed by the longitude. As an example, place A is defined as 2354N 7305E. This implies that the place is 23* 54’ North of the equator and 73* 05’ East of the PM.
Change of Latitude or Difference of Latitude (Ch lat or D lat)
Ch lat between two places is the arc of the meridian intercepted between their respective parallels of latitude, and can be North or South depending upon the direction of change.
Discuss Ch lat in same hemisphere/ opposite hemisphere.
Change of Longitude or Difference of Longitude (Ch long or D long)
Ch long between two places is the smaller arc of the equator intercepted between the meridians passing through the two places, and is East or West depending on the direction of change.
Discuss Ch long in same hemisphere/ opposite hemisphere.
Solar System and the Earth: Our solar system comprises of nine planets revolving around the sun at different distances. The closest planet to the sun is ‘Mercury’, followed by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune; with Pluto being the farthest from the Sun. Mercury completes one orbit around the Sun in about 88 days and Pluto in about 249 years.
Sphere: A sphere is a solid body bounded by a surface upon which all points are equidistant from the centre. Radius of all points on the surface of the sphere is the same.
The Earth
The Earth revolves around the Sun in an elliptical orbit, taking about 365¼ days to complete one orbit. It also rotates around its own axis, from West to East, once in approx 24 hours. Its axis of rotation is tilted at an angle of 66.5° to the elliptical plane of its revolution around the sun. This causes seasons. Its rotation about its own axis causes day and night.
The earth is an oblate spheroid – i.e. not a perfect sphere, but can be considered to be a perfect sphere for all practical purposes. It is flattened at the poles, with the equatorial diameter (12748.6 kms) being 43 kms more than the polar diameter (12705.6 kms). The flattening at the poles is called Compression.
Compression Ratio = 43/12748.6 = 1/ 296.5
Poles
The points of intersection of the axis of rotation of the earth and the earth’s surface are called poles – North and South pole. The names have been arbitrarily selected. The North pole is the pole about which the earth rotates anti-clockwise; and rotates clockwise about the S-pole, when viewed from above the respective pole.
Great Circle (GC)
It is a circle on the surface of the sphere (earth) whose radius and centre are same as that of the earth. It is the largest circle that can be drawn on the surface, and thus its name. A GC has certain properties. These are as follows: -
• It divides the sphere into two equal halves.
• It has the same radius and centre as the sphere.
• Only one GC can be drawn through two points not diametrically opposite.
• Any number of GCs can be drawn through two diametrically opposite (anti-podal) points.
• The shortest distance between two places is the smaller arc of the GC drawn through them.
Small Circle
Any circle on the surface of the sphere (earth) that is not a GC is a small circle. A small circle’s radius and centre would thus not be the same as that of the earth.
Equator
Equator is a GC whose plane is at right angles to the axis of rotation of the earth, and it divides the earth into two equal halves – the Northern and Southern hemispheres. It is the datum for measuring latitude. Thus latitude is either North or South of the equator. Also, equator itself is 0° latitude.
Meridians
Meridians are semi GCs joining from pole to pole. Thus every GC passing through the poles comprises of a meridian and its anti-meridian. All meridians cut the equator at 90°.
Rhumb Line (RL)
A RL is a regularly curved line on the surface of the earth that cuts all meridians at the same angle. It can also be called as the line of constant true direction. So, aircraft flying constant true track would be flying RL track. Other points of interest are: -
• Only one RL can be drawn through any 2 points.
• RL is not the shortest distance between 2 points, but is convenient to fly.
• All meridians and equator are the only examples of GC that are also RL.
• All parallels of latitude and meridians intersect with each other at 90°. So all parallels of latitude are RLs.
Prime Meridian (PM)
The meridian passing through Greenwich Village (close to London) is called the Prime Meridian, and is the datum for measuring longitude. Thus longitude is either East or West of the Prime meridian. Also, the longitude of the PM is 0°.
Parallel of Latitude
Parallels of latitude are small circles whose plane are parallel to the plane of the equator, and cut all meridians at 90°.
Graticule
This network of parallels of latitude and the meridians drawn on the surface of the earth is called a graticule.
Latitude
Latitude of a place is the arc of the meridian between the equator and the parallel of latitude on which the place lies. It is measured in degrees, minutes, seconds North or South of the equator. (1° = 60’ and 1’ = 60”). Latitude is the angular distance along the meridian.
What is the latitude of the North pole? Why? Can you explain.
Longitude
Longitude of a place is the smaller arc of the equator measured between the PM and the meridian passing through the place. It is measured in degrees, minutes and seconds East or West of the PM. Longitude is the angular distance along the equator.
Defining Position on the Earth
Position on the earth can be defined in any of the following manners: -
• Place Name
• Bearing and distance from known place
• Latitude/ Longitude
Conventionally a place is defined in lat/ long, by the latitude first followed by the longitude. As an example, place A is defined as 2354N 7305E. This implies that the place is 23* 54’ North of the equator and 73* 05’ East of the PM.
Change of Latitude or Difference of Latitude (Ch lat or D lat)
Ch lat between two places is the arc of the meridian intercepted between their respective parallels of latitude, and can be North or South depending upon the direction of change.
Discuss Ch lat in same hemisphere/ opposite hemisphere.
Change of Longitude or Difference of Longitude (Ch long or D long)
Ch long between two places is the smaller arc of the equator intercepted between the meridians passing through the two places, and is East or West depending on the direction of change.
Discuss Ch long in same hemisphere/ opposite hemisphere.
No comments:
Post a Comment