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section-latitude-longitude.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>map school: Latitude & Longitude</title>
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<h1><a href='./'>map school: Latitude & Longitude</a></h1>
<p>a free introduction to geo.</p>
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<p>The most common way to store places on earth is with latitude and longitude values. Historically latitude and longitude are sometimes represented in sexagesimal notation, like <code>38° 32'</code>, but the new standard is to represent them as simple numbers, like <code>38.2</code>, that are easy for computers to understand.</p>
<p><img src="img/latlon.png" alt=""></p>
<p><strong>Latitude</strong> values range from -90 at the South Pole to 90 at the North Pole. All along the equator the latitude value is 0.</p>
<p><strong>Longitude</strong> start at 0 at the Prime Meridian which cuts through Africa and Greenwich, and extends to -180 and 180 at the antemeridian.</p>
<p>The combination of latitude and longitude is usually called a coordinate, and can be represented as 'latitude, longitude', or 'longitude, latitude': historically, the former was standard, but 'longitude, latitude' has recently gained popularity because it mirrors the 'X, Y' ordering of coordinates in math's euclidean space.</p>
<p>Coordinate ordering can cause some confusion, as browser based mapping software often expects 'latitude, longitude', whereas many wire formats specify 'longitude, latitude'.</p>
<p>Sometimes more than just the latitude, longitude position is recorded as data: altitude can also be included, as well as time of capture and other factors. In the case of including altitude, it's usually stored as a third coordinate, like 'longitude, latitude, altitude.'</p>
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