Latitude and Longitude: Difference between revisions
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===== Degrees, Minutes and Seconds ===== | ===== Degrees, Minutes and Seconds ===== | ||
Recording a location by longitude | Recording a location by latitude and longitude has a long history associated with the history of navigating at sea. Traditionally, latitude varies from 0 to 90 degrees north or south with each degree divided into 60 minutes and each minute divided into 60 seconds. Note that these minutes and and seconds have nothing directly to do with time. Exactly 0 degrees latitude is associated with the equator. In contrast, longitude varies from 0 to 180 degrees west or east with 0 degrees corresponding to the longitude of Greenwich, England. As with latitude, each degree of longitude has been traditionally divided into 60 minutes and each minute into 60 seconds. Longitudes east of Greenwich are referred to as east (E) latitudes and those west of Greenwich as west (W). This system is referred to as sexagesimal or DMS format. | ||
===== Degrees and Minutes ===== | ===== Degrees and Minutes ===== | ||
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With the advent of computers and GPS satellites, dividing degrees into minutes has become less common. Instead, latitude and longitude are expressed as degrees with many digits after the decimal point, for instance 45.471687 N, 122.728182 W. Finally, the North (N) or South (S) is often left off the latitude in favor of using positive numbers for latitudes north of the equator and negative numbers for south of the equator. Similarly, longitudes west of Greenwich are often reported as negative numbers and those east reported as positive numbers. This format where only positive or negative degrees are reported is referred to as '''Decimal Degrees'''. For example, 45.471687, -122.728182. | With the advent of computers and GPS satellites, dividing degrees into minutes has become less common. Instead, latitude and longitude are expressed as degrees with many digits after the decimal point, for instance 45.471687 N, 122.728182 W. Finally, the North (N) or South (S) is often left off the latitude in favor of using positive numbers for latitudes north of the equator and negative numbers for south of the equator. Similarly, longitudes west of Greenwich are often reported as negative numbers and those east reported as positive numbers. This format where only positive or negative degrees are reported is referred to as '''Decimal Degrees'''. For example, 45.471687, -122.728182. | ||
=== Converting Between Formats === | |||
The history summary above may be somewhat interesting but it leads to many ways of reporting latitude and longitude. Because most of the tools we have at our disposal use Decimal Degrees, we will use that format for our exercises. If you find that the app you are using produces a different format, you can convert that format to decimal degrees. For instance, the FCC provides a [https://www.fcc.gov/media/radio/dms-decimal web page] that converts between degrees/minutes/second and decimal degrees. You may need to add the negative sign to the longitude, however, assuming you are converting a location in the western hemisphere. | |||
=== Voicing Latitude and Longitude === | === Voicing Latitude and Longitude === | ||
