The latitude is the angle formed by a line going from the center of the earth to the equator at the point on the equator that is closed to the point of interest and another line that goes from the center of the earth to the parallel that goes through the point of interest.
Latitude is a measurement on a globe or map of location north or south of the Equator.
Lines joining places with the same latitudes are called parallels ie the lines running East to West are called “Parallels” or “lines of latitude”
Technically, there are different kinds of latitude—geocentric, astronomical, and geographic (or geodetic)—but there are only minor differences between them.
In most common references, geocentric latitude is implied.
Given in degrees, minutes, and seconds, geocentric latitude is the arc subtended by an angle at Earth’s centre and measured in a north-south plane poleward from the Equator. Therefore, the greatest possible latitudes are 90° N and 90° S.
The value of equator is 0° and the latitude of the poles are 90°N and 90°S.
If parallels of latitude are drawn at an interval of one degree, there will be 89 parallels in the northern and the southern hemispheres each.
The total number of parallels thus drawn, including the equator, will be 179.
Depending upon the location of a feature or a place north or south of the equator, the letter N or S is written along with the value of the latitude.
If the earth were a perfect sphere, the length of 10 of latitude (a one degree arc of a meridian) would be a constant value, i.e. 111 km everywhere on the earth.
This length is almost the same as that of a degree of longitude at the equator.
But to be precise, a degree of latitude changes slightly in length from the equator to the poles.
While at the equator, it is 110.6 km at the poles, it is 111.7 km.
Latitude of a place may be determined with the help of the altitude of the sun or the Pole Star.
As aids to indicate different latitudinal positions on maps or globes, equidistant circles are plotted and drawn parallel to the Equator and each other; they are known as parallels, or parallels of latitude.
In contrast, geographic latitude, which is the kind used in mapping, is calculated using a slightly different process.
Because Earth is not a perfect sphere—the planet’s curvature is flatter at the poles—geographic latitude is the arc subtended by the equatorial plane and the normal line that can be drawn at a given point on Earth’s surface.
The length of a degree of arc of latitude is approximately 111 km (69 miles), varying, because of the nonuniformity of Earth’s curvature, from 110.567 km (68.706 miles) at the Equator to 111.699 km (69.41 miles) at the poles.
Geographic latitude is also given in degrees, minutes, and seconds.
