Earth, Parallels and Meridians, Latitude and Longitude [IGEO TV ]
Both, meridians and parallels, form the geographic coordinate system based on latitude and longitude
Meridians are the terrestrial geoid highs semicircles passing through the poles, imaginary lines used to determine the microseconds. By extension, are also the maximum semicircles passing through the poles of any reference sphere or spheroid. All observers located on the same meridian are at the same time, in the lighted half of Earth, the Sun at the top of its course when the Sun is at the top of the course indicating noon.
By resolution, adopted at an international conference held in 1884 in Washington, and sponsored by then President of the United States, attended by delegates from 25 countries, the "reference meridian ", from which lengths are measured , i.e. , which is considered the "longitude 0 °", is the Greenwich meridian, so called because it passes through the ancient observatory in Greenwich.
Circle formed by the intersection of land area with an imaginary plane perpendicular to the axis of rotation of the Earth is called parallel.
On the parallels, and from the Greenwich meridian, meridian that is taken as origin, measure the length, the circle is expressed in degrees, which may be East or West, depending on the direction of measurement of the same. Unlike meridians, parallels are not as great circles, except Equator, do not contain the center of the Earth.
The angle ( with vertex at the center of the Earth ) on any plane parallel and meridian for the equator is called latitude and is the same for all points of the parallel , which discriminates between North and South latitude, according to hemisphere.
There are five main striking parallels or corresponding to a particular position of the Earth in its orbit around the sun, and therefore receives a particular name:
-Arctic Circle (latitude 66 ° 33 ' N = 90 º - 23 º 27').
-Tropic of Cancer (latitude 23 ° 27 ' N). It further north latitude at which the sun reaches its zenith. This occurs at the June solstice.
- Equator (latitude 0 °). In Equator the Sun culminates at the zenith on the equinox of spring and autumn.
- Tropic of Capricorn (latitude 23 ° 27 ' S). Is the parallel further south where the sun reaches the zenith. This occurs at the December solstice.
- Antarctic Circle (latitude 66 ° 33 ' S).
Watch Video 3D Earth Globe: