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Registered Penn State students should return now take the self-assessment quiz about Geographic Coordinates. To convert 43° 4' 31" from degrees, minutes, seconds to decimal degrees, use the simple formula below:ĭD = Degrees + (Minutes/60) + (Seconds/3600)ĭivide the number of seconds by 60 (31 ÷ 60 = 0.5166).Īdd the quotient of step (1) to the whole number of minutes (4 + 0.5166).ĭivide the result of step (2) by 60 (4.5166 ÷ 60 = 0.0753).Īdd the quotient of step (3) to the number of whole number degrees (43 + 0.0753). If the starting point had been the Longitude of -89.400062, the only difference would be that the S above would be replaced by a W. Round off (to the nearest second in this case).Īssemble the pieces the result is 89° 24' 2" S. Multiply the remainder by 60 seconds (.0372 x 60 = 2.232). Subtract the number of whole minutes (24') from the product. (The minus sign is used in the decimal degree format only to indicate that the value is a west longitude or a south latitude.) In this example, the minus sign indicates South, so keep track of that. Subtract the number of whole degrees (89°) from the total (89.40062°). To convert Latitude of -89.40062 from decimal degrees to degrees, minutes, seconds: Sometimes, you need to convert from one form to another. Geographic coordinates may be expressed in decimal degrees, or in degrees, minutes, and seconds. Geographic coordinates often need to be converted in order to geo-register one data layer onto another. The degree is equal to sixty minutes, and each minute equal to sixty seconds. We have discussed the fact that both latitude and longitude are measured in degrees, but what about when we need a finer granularity measurement? To record geographic coordinates, we can further divide degrees into minutes, and seconds. Longitude and Latitude Practice 2.2.1 Geographic Coordinates You’ll practice by clicking locations on a globe as specified by randomly generated geographic coordinates. The websites linked below let you test your knowledge. Have you ever encountered the terms ‘latitude’ or ‘longitude’? How well do you understand the geographic coordinate system, really? Our experience is that while everyone who enters this class has heard of latitude and longitude, only about half can point to the location on a map that is specified by a pair of geographic coordinates. Try This: Geographic Coordinate System Practice Application Thus, while a degree of longitude at the equator is equal to a distance of about 111 kilometers, that distance decreases to zero at the poles. Lines of longitude are not parallel, but converge toward the poles. At higher latitudes, the length of parallels decreases to zero at 90° North and South. Opposite the International Date Line on the other side of the globe is the prime meridian, the line of longitude defined by international treaty as 0°. That +/- 180 grid line is roughly the International Date Line, which has diversions that pass around some territories and island groups so that they do not need to cope with the confusion of nearby places being in two different days. A line of longitude is called a meridian.
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Because the Earth is round, +180° (or 180° E) and -180° (or 180° W) are the same grid line. The east-west scale, called longitude (conventionally designated by the Greek symbol lambda), ranges from +180° to -180°. A line of latitude is also known as a parallel. The north-south scale, called latitude (designated by the Greek symbol phi), ranges from +90° (or 90° N) at the North pole to -90° (or 90° S) at the South pole while the equator is 0°. A comparison of these two scales is given below in Figure 2.4. You have probably encountered the terms latitude and longitude before in your studies. Instead of the two linear measurement scales x and y, the geographic coordinate systems bring together two curved measurement scales. However, the geographic coordinate system, as seen in Figure 2.3, is designed specifically to define positions on the Earth's roughly spherical surface. They are not perfectly suited to specifying geographic positions. Credit: © Penn State University, is licensed under CC BY-NC-SA 4.0Ĭartesian and other two-dimensional (plane) coordinate systems are handy due to their simplicity.