The fundamentals and conversion.
What are Latitude and Longitudes?
The ellipsoid shape of the Earth is asymmetrical. In order to create a net or grid on maps and globes, our mapmakers came up with a system of imaginary lines. Thus, there are numerous horizontal and vertical lines drawn on maps to aid in locating a location. Latitude and Longitude are the two numbers that identify any location on Earth. Parallels or Lines of Latitude are the imaginary lines that go from East to West (left to right). Meridians or lines of longitude are the imaginary lines that start from the poles and travel from top to bottom (North to South). The Earth is split into two equal hemispheres by the equator. The most significant longitude line is the Prime Meridian. A 0-degree longitude defines its location.
In the same way, a circle has 360 degrees the Earth has 360 degrees. These measurements are angular. The Equator is at 0 degrees latitude, whereas the Prime Meridian, which is in Greenwich, England, is at 0 degrees longitude. Using a decimal number, we can represent any latitude or longitude. Negative latitudes represent the southern hemisphere, and negative longitudes represent the western hemisphere.
Let’s delve a bit more into this. Latitude has a value of 0° at the equator, 90° at the north pole, and 90° at the south pole. If the latitude values are positive and fall between 0° and 90°, they represent the north; otherwise, they represent the south. Likewise, it is 0° longitude at the Prime Meridian. The range of longitude values is 0° to 180° east or 0° to 180° west. Longitudes that are positive are east of the prime meridian, and those that are negative are west of it.
For expressing the angular values of latitude and longitude, one can use the Degree, Minute, Seconds(DMS) or Decimal Degree number systems. Therefore, let’s discuss how to define a location in DMS and DD format and how to convert vice versa.
Three ways
It is possible to represent the latitude and longitude of a place in three different ways. For instance, let us take the location of the CN Tower in Toronto, Canada. Here are the ways to express the location:
When we have a given location, it may be in either of these formats.
First, let us take the Decimal Degree format. Here the latitude, 43.642567 can be written as 43 + 0.642567 and the integer part, 43 is the degree value. You can convert the decimal part to minutes by multiplying by 60.
0.642567*60 =38.55402 minutes = 38.55402′.
So 43.642567 can be written as 43° 38.55402′
Again we can convert the minutes into minutes and seconds. In the above value, integer 38 is the minute part, and if we multiply the decimal part 0.55402 by 60, we will get the value in seconds.
0.55402′ X 60 = 33.2412 seconds = 33.2412’’
So, 43° 38.55402′ can be written as 43° 38′ 33.2412’’
The given latitude value is positive. As mentioned earlier, if the Latitude values range between 0° and 90° in positive it represents north. So
43° 38′ 33.2412’’ can be written as 43° 38′ 33.2412’’ N
Let us repeat the above procedure for the Longitude value. The decimal degree value is -79.387054. Which means,
Here the longitude value is given in negative. As mentioned earlier, longitude values range from 0° to 180° east or from 0° to 180° west. Positive longitudes are east of the prime meridian, and negative ones are west. Hence, -79° 23′ 13.3944″ is 79° 23′ 13.3944″ W.
It’s as simple as this. Okay, now consider a situation where we have to convert the DMS format to decimal degrees. We have to reverse the process.
Suppose 43° 38′ 33.2412’’ N is the given value.
Though there are many online convertors, it is important to know the basic concept. Please leave a comment below if you have any questions or would like to share any additional information.