3 Ways to Determine Latitude and Longitude

2024 Author: Samantha Chapman | [email protected]. Last modified: 2023-12-17 09:13

Latitude and longitude are parameters that allow you to determine the exact position of each point on the globe. There are several ways to find them, and some need more tools than others. Once you understand the basics, find geographic coordinates with a map and protractor.

Steps

Method 1 of 3: Understanding Longitude and Latitude

Step 1. Latitude

This coordinate measures the distance of a point from the equator, both north and south. Since the Earth is spherical, the distance from the equator is measured in degrees, where the equator itself is equal to 0 °, while the north and south poles both correspond to 90 °.

Latitude is measured in "degrees north" when considering a point in the northern hemisphere and in "degrees south" when considering a point in the southern hemisphere

Step 2. Longitude

This coordinate measures the distance of a point east or west of the fundamental meridian that has been arbitrarily identified in the Greenwich meridian in Great Britain. Also in this case, since the Earth is round, the distance from the fundamental meridian is measured in angular degrees; the Greenwich meridian corresponds to 0 °. As you move west or east the longitude increases up to 180 °.

• The 180 ° meridian is known as the international date line.
• Longitude is expressed in east degrees when considering the eastern hemisphere and in west degrees when considering the western hemisphere.

Step 3. Learn about the accuracy of the detections

Degrees are a rather large unit of measurement to get a precise location, so geographic coordinates are divided into decimal points called decimal degrees. For example, we can come across latitude 35, 789 degrees north. The Global Positioning System (GPS) often uses decimal degrees, but most printed maps don't.

Online topographic maps express longitude and latitude in degrees, minutes and seconds (DMS system). Each degree equals 60 minutes, while each minute equals 60 seconds. The analogy with the measure of time makes the subdivision very simple

Step 4. Learn how they appear on the map

First assume that the top of the map is north. The numbers on the left and right indicate the latitude, while the numbers you can read at the top and bottom of the image refer to the longitude.

• Remember how time measurements are converted, so you can learn how to use the DMS system:

  • 15 seconds = quarter of a minute = 0.25 minutes;
  • 30 seconds = half a minute = 0.5 minutes;
  • 45 seconds = three quarters of a minute = 0.75 minutes.

  Method 2 of 3: Using a Map

  

  Step 1. Get a map of the area of your interest

  Choose a good quality product, very detailed and that also indicates the contour lines. You can find these maps in the library, but also in the best-stocked bookstores.

  

  Step 2. Look for latitude and longitude values

  These measurements are usually often found in the corner of the map. Under the title you can also find the extent of the mapped area. For example, you can find a map that shows the value 7, 5, which means that it shows an area of 7, 5 minutes of latitude and as many of longitude.

  

  Step 3. Find the location

  Depending on the scale at which the map was drawn, it may take some time to find the exact spot you are interested in. Locate the city, town or specific point that denotes your current location. Once you find it, make a mark on it. Among the information you can find on the map there is also the scale that allows you to quickly calculate the distance relative to a known geographical reference point, in case you do not know the name of the city you are looking for. This detail allows you to find the position more quickly.

  Depending on the place you are looking for, make sure the map is of the proper scale. If you want to know the distance that separates your home from another region, then you should use a map of Italy, instead of a map of all of Europe

  

  Step 4. Use a chart ruler to check the degrees

  From the point you have located, draw a straight line out of the map to find the corresponding latitude or longitude value. The map should be divided into horizontal and vertical lines which represent latitude and longitude respectively. In the four corners of the image you should see the coordinates written in full, while for all intermediate values only the last two digits will be indicated.

  • The image should have latitude and longitude lines forming a grid by dividing the map into sections. The map ruler is simple to use and you can buy it at camping supply stores and even online. Make sure that the ruler respects the standard scale with which the map is drawn.
  • First measure the latitude. The lines that correspond to this coordinate run horizontally, parallel to each other and there will be one north and one south of your position. Rest the zero end of the ruler on the southern parallel, while the northern parallel should be at the end of the instrument indicating 2.5 minutes. One edge of the ruler is divided into minutes and seconds, and the other edge into decimal minutes. Make sure you are using the right side based on the format used by your map. Slide the ruler to the right, i.e. east, until the instrument encounters the location of your interest and note the distance that separates it from the southern parallel. Add this value to the latitude corresponding to the southern parallel and you will have the latitude of your location.
  • To measure longitude you must place the ruler diagonally on the eastern and western meridians with respect to the location. Make sure that the two ends that show the value 2, 5 minutes each fall on the corresponding meridian. The longitude lines of the point you are studying on the map are the meridian east and west of the point itself. You have to hold the ruler diagonally because, if you held it horizontally, the ends would go outside the limits of the grid because the meridians get closer together as they move away from the equator. Slide the ruler vertically until its edge intersects the area of interest, but make sure that both ends are resting on the meridians. Note the location of the location - in minutes and seconds west - starting from the easternmost meridian. To find the total longitude of the point on the map, add this value to the longitude corresponding to the eastern meridian.

  

  Step 5. Write the coordinates

  The standard procedure is to first note the latitude followed by the longitude and both must be indicated with as many decimal places as possible. The more decimals you can get, the more precise the location will be.

  • When you write the coordinates, you can express them in different formats:

    • Degrees (d.d °): for example 49.5000 °, -123.5000 °;
    • Degrees decimal minutes (d ° m.m '): for example: 49 ° 30.0', -123 ° 30.0 ';
    • Degrees, minutes, seconds (d ° m's): for example 49 ° 30'00 "N, 123 ° 30'00" W.
  • When it comes to latitude and longitude, the "north", "south", "east" and "west" indicators are replaced by the negative sign ("-") when dealing with coordinates south of the equator and west of the fundamental meridian.

  Method 3 of 3: Measure with a protractor

  

  Step 1. Make sure it's noon

  Latitude can be determined using the sun only when it is plunging into the sky. Check the clock or stick a stick vertically into a dial at the southernmost line. You can say that it is noon when the shadow of the stick is perfectly aligned with the north-south direction of the dial.

  Use a plumb line to make sure the stick is perfectly vertical. The plumb line is exactly what its name suggests: a string with a plumb bob tied at the end that creates a vertical line

  

  Step 2. Determine north and south with a compass

  You can only start taking measurements when you have identified where north and south are. Draw a line on the ground indicating these two cardinal points. Finally set up a quadrant with an arm parallel to this line.

  

  Step 3. Make a quadrant or cross using two pieces of wood

  The stick you use to point the sun should be centered on the base one, so that it can rotate up or down. In addition, there should be 4 nails on this "pointing" stick, two at each end.

  Center the protractor at the intersection of the dial. Always hang a plumb line at the intersection

  

  Step 4. Align the nails with the sun

  When it is noon, align the nails of the aiming arm with the sun, without looking directly at the light. Instead, try to take advantage of the shadow position of the nails by moving the stick until you find perfect alignment. Move the stick up and down until the two shadows created by the nails merge into one on the ground.

  

  Step 5. With the protractor, measure the small angle created between the stick and the plumb line

  When the club is aligned, you need to find the width of the angle formed by the vertical plumb line and the club. Maintain a 90 ° horizon at this stage.

  

  Step 6. Know that the time of year affects the accuracy of your measurement

  In fact, it will be precise only at the autumn and spring equinoxes, that is, on the 21st of September and March. If you are taking measurements on December 21st or mid-winter, take 23.45 ° off the result. Conversely, if you are measuring the position in the middle of summer, around June 21, add 23.45 °.

  • The values obtained with this method are not entirely accurate, except at the equinoxes, because the Earth tilts on its vertical axis as it orbits the sun.
  • Although there are complex tables that give you the correct factor to calculate the latitude and longitude on each day of the year, the correct estimate is always around the autumn and spring equinox. For example, if you're taking measurements in early March, which is roughly midway between spring (when the sun is directly above the equator) and the summer solstice (when the sun is at 11pm, 45 ° north from the equator) then you need to add 11.73 ° to your measurements.

  Advice

  • Online calculators are a useful tool for calculating latitude and longitude in a simple way.
  • You can also download applications for mobile devices, including those with a GPS system, which help you determine geographic coordinates.