What are latitudes and longitudes in geography

Longitude and Latitude: Geographic coordinates

The coordinate system

The globe is initially divided into 180 degrees of latitude and 360 degrees of longitude.

  • Lines of latitude run parallel to the equator.
    On a north-facing map, they are approximately horizontal.
  • Longitudes connect the north and south poles.
    On a north-facing map, they are vertical.

This creates a large-meshed grid that can be used to indicate the approximate position on the earth's surface.

To improve accuracy, each degree of latitude and longitude (°) is also subdivided into 60 minutes (′) of 60 seconds (″) each.

Find planets & stars: Horizontal coordinate system

Latitude: angle to the equatorial plane

The circles of latitude run on an east-west axis and thus describe the north-south dimension of a place on the earth's surface.

The equator runs at right angles to the earth's axis and lies roughly in the middle between the north and south poles. With an angle of 0 °, it is the starting point for calculating the parallels in the geographic coordinate system.

The geographical latitude is given as the angle between the line of the center of the earth and the equator and the line of the center of the earth and the location. The north and south poles have a latitude of 90 °. In order to distinguish places in the northern hemisphere from those in the southern hemisphere, the latitude in the traditional notation is additionally provided with an N for north or an S for south.

Example: Alexanderplatz in Berlin is located at 52 ° 31'18 ″ N (north latitude). If you draw a straight line from there to the center of the earth, it would have exactly this angle to the equatorial plane or to a line on the same degree of longitude from the equator to the center of the earth.

The main parallels

  • The arctic circles lie at 66 ° 34 ′ north and south latitude. These parallels delimit the regions around the poles in which the sun does not set at the summer solstice, where the midnight sun then prevails. At the winter solstice, the sun does not rise here, it is a polar night.
  • The tropics lie at 23 ° 26 ′ north and south latitudes. These circles of latitude mark the places over which the sun is at its zenith on the two annual solstices (exactly perpendicular) - i.e. the northernmost and southernmost positions of the sun of the year.
  • The equator is at 0 °. The equatorial plane runs roughly through the center of the earth's axis between the north and south poles. The equator is the only parallel that corresponds to the circumference of the earth.

How do seasons arise?

Longitude: angle to the prime meridian

The longitudinal circles run on a north-south axis and thus describe the east-west dimension of a place on the earth's surface.

As circles spanning the earth, they pass through the north and south poles and cross the equator. Each longitude represents the circumference of the earth. One half of the longitudinal circle connecting the poles is called a meridian.

Unlike the latitudes, the angles of which are derived from the equator, the longitudes do not have a natural zero point. Because of this, different starting points were used depending on the country until the early 20th century. Today, the meridian that runs through the London borough of Greenwich is considered the prime meridian and thus the starting point for calculating longitudes.

Is the Prime Meridian in the wrong place?

The geographical longitude is given as the angle between the line of the earth's center-prime meridian and the line of the earth's center-point. The Greenwich Meridian has an angle of 0 °, while the opposite longitude, along which the date line runs, has an angle of 180 °.

The prime meridian divides the earth's surface into a western and an eastern hemisphere. In order to distinguish between places on the two hemispheres, the traditional spelling also adds a W for west or an O for east.

Example: The Sydney Opera House is at 151 ° 12'50.5 "E (east longitude). If you draw a straight line from there to the center of the earth, it would have exactly this angle to a line on the same latitude from the prime meridian to the center of the earth.

Longitudes and time zones

With the east-west dimension, the solar time of a place can also be described due to the parallel running earth's rotation using the longitudes. The same solar time prevails in all places that are on the same degree of longitude.

What and when is the real noon?

That is why the earth's time zones are initially based on longitude. Ideally, each time zone is exactly 15 degrees wide. In reality, however, the time zone boundaries are distorted by political and geographical factors, so that the zone time often deviates quite far from the course of the sun. This is the case in parts of Europe, for example.

Time zones world map

Spellings

When specifying geographic coordinates, one of two spellings is usually used today:

The sexagesimal system

This is the traditional way of writing. The sexagesimal system is a number system based on the number 60. Here the coordinates consist of three components:

  • Longitudes and latitudes are given as angles (°).
  • Each degree has 60 minutes. These are indicated by a prime (′).
  • Every minute has 60 seconds, which can be identified by a double prime (″).

In nautical science and aviation, the longitude is usually given as a three-digit number in order to visually distinguish it from the latitude and thus avoid misunderstandings.

The Zugspitze has the coordinates 47 ° 25'16 "N, 010 ° 59'7" E.

The decimal notation

In parallel to the traditionally used sexagesimal system, the specification of coordinates in the decimal system has also become established. The decimal system is based on the number 10. Here the fraction of the respective longitude and latitude is given by any number of decimal places. Places in the western and southern hemisphere are preceded by a minus (-).

In the decimal system the coordinates of the Zugspitze are given as follows: 47.4211, 010.9852.

Machu Picchu, located in the western part of the southern hemisphere, has the coordinates
-13.163333, -072.545556.

Subjects: Timekeeping, time zones, geography, navigation, earth