Latitude

Latitude is a measurement that specifies the north-south position of a point in the geographic coordinate system. It is measured in degrees (°) and ranges from 0° to 90° north or 90° south, spanning a total of 180°.

You can think of the geographic coordinate system as dividing the earth up into a grid, with latitude telling you the north-south position, and longitude telling you the east-west position.

If you are familiar with the coordinate plane, the concept of latitude and longitude are similar to the x and y position on the coordinate plane, except that the geographic coordinate system lies in 3D, as part of a sphere, rather than in 2D, on a plane.

In the geographic coordinate system, the equator divides the Earth into its northern and southern hemispheres, similar to the x-axis in the coordinate plane.

Expressing latitude

The primary unit of latitude is degrees, but it can be further broken up into minutes (') and seconds ("):

1° = 60' = 3600"

This allows us to be more precise, since not all positions that we want to reference will align with a whole degree since each degree of latitude is approximately 69 miles on earth. 42°3'27" N is one example of how we can write a latitude. It is read as "42 degrees, 3 minutes, 27 seconds north." We can also write the 3'27" portion of the latitude in decimals. To do this, we convert the minutes and seconds into their fractions of a degree:

 = = =

We divide the minute portion by 60 because 1 minute is degrees. Similarly, 1 second is degrees.

When writing latitude and longitude, we always write the latitude first. So, if giving the coordinates of Houston, TX, we could write it as:

Degrees minutes seconds: 29°45'47.808" N 95°21'47.772" W

Decimal degrees: 29.76328° N 95.36327° W

These aren't the only ways latitude and longitude can be written. There are a number of other ways. For example, instead of specifying a direction like N for north, or W for west, we could use positive and negative numbers. Positive latitude indicates north and negative latitude indicates south. Positive longitude indicates east and negative longitude indicates west.

Did you know?

The equator, North Pole, and South Pole have a latitude of 0°, 90° N, and 90° S, respectively.

Both Minneapolis, Minnesota (USA), and Bordeaux, France, are located about 45° N. This latitude is halfway between the equator and the North Pole.