An Introduction Of Latidudes and Longitude (लंगीच्युद र ल्यातिच्यूद को परिचय)

An Introduction of Latitudes and Longitude (लंगीच्युद र ल्यातिच्यूद को परिचय)

Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees (marked with °). The equator has a latitude of 0°, the North pole has a latitude of 90° north (written 90° N or +90°), and the South pole has a latitude of 90° south (written 90° S or −90°). Together, latitude and longitude can be used as a geographic coordinate system to specify any location on the globe.


Curves of constant latitude on the Earth (running east-west) are referred to as lines of latitude, or parallels

Map of Earth

Lines of longitude appear vertical with varying curvature in this projection, but are actually halves of great ellipses, with identical radii at a given latitude.

Lines of latitude appear horizontal with varying curvature in this projection; but are actually circular with different radii. All locations with a given latitude are collectively referred to as a circle of latitude.

The equator divides the planet into a Northern Hemisphere and a Southern Hemisphere, and has a latitude of 0°.

In geography, the latitude of a location on the Earth is the angular distance of that location Each line of latitude is actually a circle on the Earth parallel to the equator, and for this reason lines of latitude are also known as circles of latitude. In spherical geometry, lines of latitude are examples of circles of a sphere, with the equator being a great circle.
Latitude (usually denoted by the Greek letter phi (φ)) is often measured in degrees, minutes and seconds. The Eiffel Tower has a latitude of 48° 51′ 29″ N-- that is, 48 degrees plus 51 minutes plus 29 seconds. Or latitude may be measured entirely in degrees, e.g. 48.85806° N.
If the Earth were actually spherical, and homogenous, and not rotating, then latitude at a point would just be the angle between a vertical line at that point and the plane of the equator. Everywhere on Earth a vertical line would point to the center of the Earth. In reality the earth is rotating and is not spherical, so a vertical line — a line in the direction of apparent gravity — doesn't point to the center of the Earth (except at the poles and the equator). If the Earth were homogenous, then a vertical line would still point to some point on the Earth's axis, and latitude at a point would still be the angle between the vertical line there and the plane of the equator.
But the Earth is not homogenous, and has mountains-- which have gravity and so can shift the vertical line away from the Earth's axis. The vertical line still intersects the plane of the equator at some angle; that angle is astronomical latitude, the latitude you would calculate from star observations. The latitude shown on maps and GPS devices is the angle between a not-quite-vertical line through the point and the plane of the equator; the not-quite-vertical line is perpendicular to the surface of the spheroid chosen to approximate the Earth's sea-level surface, rather than perpendicular to the sea-level surface itself.

Longitudes

Points with the same longitude lie in lines running from the North Pole to the South Pole. By convention, one of these, the Prime Meridian, which passes through the Royal Observatory, Greenwich, England, establishes the position of zero degrees longitude. The longitude of other places is measured as an angle east or west from the Prime Meridian. Specifically, it is the angle between a plane containing the Prime Meridian and a plane containing the North Pole, South Pole and the location in question. If the direction of longitude (east or west) is not specified, positive longitude values are east of the Prime Meridian, and negative values are west of the Prime Meridian. This forms a right-handed coordinate system with the z axis (right hand thumb) pointing from the Earth's center toward the North Pole and the x axis (right hand index finger) extending from Earth's center through the equator at the Prime Meridian.
A location's north-south position along a meridian is given by its latitude, which is the angle between the local vertical and the plane of the Equator.

If the Earth were perfectly symmetrical and homogenous, then longitude at a point would just be the angle between a vertical north-south plane through that point and the plane of the Greenwich meridian. Everywhere on Earth the vertical north-south plane would contain the Earth's axis. But the Earth is not homogenous, and has mountains-- which have gravity and so can shift the vertical plane away from the Earth's axis. The vertical north-south plane still intersects the plane of the Greenwich meridian at some angle; that angle is astronomical longitude, the longitude you calculate from star observations. The longitude shown on maps and GPS devices is the angle between the Greenwich plane and a not-quite-vertical plane through the point; the not-quite-vertical plane is perpendicular to the surface of the spheroid chosen to approximate the Earth's sea-level surface, rather than perpendicular to the sea-level surface itself.

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Posted By: Daniel (Bhagwan)