Latitude and longitude are measurements used to locate specific points on the surface of the earth. They are angular measurements that range between -180 degrees and 180 degrees. The equator is the reference line from which latitude is measured and the prime meridian is the reference line for longitude. South and west are negative angles, while north and east are positive. To convert these angles to distances from their respected references, you must calculate the length of the arc the angle sweeps.
Convert the latitude and longitude measurements from degrees, minutes and seconds (DMS) to decimal notation. The conversion factors are 60 seconds per minute and 60 minutes per degree. This example is for Denver International Airport.
Lon: -104° 40’ 23” = -104° 40.3833' = -104.6731° Lat : 39° 51’ 42” = 39° 51.7’ = 39.8617°
Convert the decimal degrees to km. The conversion factor is 10,000km per 90 degrees. This factor is easier to remember and easier to use than converting directly to feet.
-104.6731 * (10,000/90) = -11,630.34km 39.8617 * (10,000/90) = 4429.1km
Convert kilometers to feet using the conversion factor 3280.4 feet per kilometer.
-11,630.34 * 3280.4 = - 3.815e7 feet 4429.1 * 3280.34 = 1.453e7 feet
The negative sign in front of the longitude value indicates the distance is west of the prime meridian. Another way to denote these measurements is:
Longitude: 3.815e7 feet W Latitude: 1.453e7 feet N