We explain what the meridians and parallels are, the characteristics of each one and how they are used. Also, the geographic coordinates.
What are meridians and parallels?
Meridians and parallels are two types of imaginary lines with which the world is usually organized geographically. With them, a coordinate system is built that allows to precisely locate any point on the globe based on its latitude and his length.
Specifically, the meridians are the vertical lines with which we can segment the globe into equal portions. They are all born at the North Pole and extend to the South (or vice versa).
For their part, the parallels are the horizontal lines that do the same. Parallel 0 is the equator. The other parallels are repeated by drawing smaller circles in both the Northern and Southern hemispheres. The combination of these two sets of lines form a grid.
Both types of lines have a point of reference From which to list both meridians and parallels, using sexagesimal degrees (expressed as follows: degrees °, minutes' and seconds' '):
- The meridians. They are measured at the rate of one degree (1 °) for each one, starting from the so-called Meridian 0 ° or Greenwich Meridian, which is the one that passes through that exact London location, where the Royal Greenwich Observatory was once. From there, the meridians can be considered East or West, depending on which direction they are with respect to this axis, and the globe is divided into 360 segments or "segments".
- The parallels. They are measured from the equator, considering the angle they form with respect to the axis of Earth's rotation: 15 °, 30 °, 45 °, 60 ° and 75 °, both in the Northern Hemisphere (30 ° N, for example), and in the South (30 ° S).
The effect of applying this system translates into:
- The system of time zones, determined by the meridians. Currently the GMT format is used (Greenwich Meridian Time, “Greenwich Mean Time”) to express the time at any time region of the world, adding or subtracting hours depending on the meridians with which each country is governed. For example, the Argentine time zone is GMT-3, while the Pakistani time is GMT + 5.
- The terrestrial climate system, determined by the parallels. From the so-called five notable parallels, which are (from North to South): the Arctic Circle (66 ° 32 '30' 'N), the Tropic of Cancer (23 ° 27' N), the equator (0 ° ), the Tropic of Capricorn (23 ° 27 'S) and the Antarctic Circle (66 ° 33' S), the globe is classified into climatic or geoastronomical zones, which are: The intertropical zone, the two temperate zones and two glacial or polar zones. Each one has similar climatic conditions due to its latitudinal location.
- The global coordinate system. That allows geolocation tools such as GPS (Global Positioning System, "Global location system").
Geographical coordinates
Meridians and parallels create a grid that allows any point to be identified.As we have seen in the previous cases, a kind of grid emerges from the union of meridians (longitude) and parallels (latitude). This geographic coordinate system consists of the expression of the value of a geographic point from its numerical record of latitude and longitude in sexagesimal degrees.
For example, the geographic coordinates of Moscow are 55 ° 45 '8' 'N (that is, its latitude in the Northern Hemisphere is between the 55th and 56th parallel) and 37 ° 36' 56 '' E (that is, its longitude is between the 37th and 38th meridian). Today, satellite location mechanisms such as GPS operate with this system.