Latitude and longitude serve to determine the exact location of any point on the globe. There are several ways to discover these details - some more complicated than others. Read the tips below and then use a map and protractor to determine the coordinates of specific points.
Method 1 of 3: Understanding Latitude and Longitude
Step 1. Understand the latitude
Latitude is the distance of a point from the equator. This point can be north or south of it. Since the Earth is round, the distance from the equator is measured in degrees, with the line representing degree zero and the point at the far north (the North Pole) being at 90°. The southernmost point (the South Pole) is also at 90°.
Latitude is measured in "degrees north" (in the northern hemisphere) or "degrees south" (in the southern hemisphere)
Step 2. Understand the longitude
Longitude is the distance of a point in relation to the primary meridian - the Greenwich meridian in England. This point can be east or west of the reference. As the Earth is round, the distance is measured in degrees, with Greenwich being at degree zero. This value increases up to 180° as we move away from the meridian to the east or west.
- The 180° longitude point is called the International Dateline.
- Longitude is represented in degrees to the east (in the eastern hemisphere) or west (in the western hemisphere).
Step 3. Understand the accuracy of the calculations
Degrees are very large units of measure; thus, to get to a specific location, latitude and longitude are divided into so-called decimal degrees. For example, latitude can be represented as "35.789° North". GPS devices usually show decimal degrees, but printed maps do not.
Virtual topographic maps express decimal degrees of longitude and latitude in degrees, minutes, and seconds. Each degree equals 60 minutes and each minute equals 60 seconds. It's easier to make the subdivision when we compare the values with time
Step 4. Understand how latitude and longitude are represented on the map
First, always assume the top of the map is north. The numbers on the right and left represent latitude, while the numbers above and below represent longitude.
- Learn how to convert time to interpret maps using decimal degrees such as degrees, minutes and seconds:
- 15 seconds: ¼ of a minute = 0.25 minutes.
- 30 seconds = ½ minute = 0.5 minute.
- 45 seconds = ¾ minute = 0.75 minutes.
Method 2 of 3: Using a Map
Step 1. Buy a map with as much information as possible
Go to a local library, stationer, or bookstore and buy a map that includes as much information as possible, such as latitude and longitude.
Step 2. Find the latitude and longitude
These values are often found in the corners of maps. Look at the region under the heading to see what area it covers. For example: a map might say that it covers 7.5 minutes - that is, it covers an area of latitude and longitude that equals 7.5 minutes.
Step 3. Find a specific location
The time to find a location on the map depends on the scale (informed in the footer of the document). For example: search for the city you live in and mark its location. After reviewing the legend, you will be able to estimate the distance to key points if you do not know the name of the location in question. This all makes the process easier.
Use a map with the ideal scale for the point you want to find. If it's still in Brazil, for example, it's better to use a map of the country alone
Step 4. Use a ruler to determine degrees
Measure from the source location to the endpoint in a straight line to determine latitude or longitude. The map is divided into vertical and horizontal lines, which represent these values. The four corners of it have the written coordinates, with only the last two digits appearing at the other points.
- The latitude and longitude lines on the map should form a sort of grid. Use a standard ruler to take measurements and calculate latitude and longitude.
- Measure latitude first. The lines of latitude run from north to south and are parallel to where you are. Place the "0" on the ruler on the southernmost parallel; the next parallel, to the north, must be at the value "2 ½". One end of the ruler shows the values in minutes and seconds, while the other ends the values in decimal numbers. Use the right tip of the accessory and slide it to the right (west) until it touches the right place. Then mark the distance between the north and south parallels to get to the final value.
- To measure longitude, you have to place the ruler diagonally on the west and east meridians, with the tips of the "2 ½" value touching both. The longitude lines on the map represent these meridians for where you are. Use the accessory crosswise; if
using it horizontally, the ruler will go past the grid, as the longitude meridians get closer as they get further away from the equator. Move the ruler vertically until you find the right spot - once again, without taking the tip off the diagonal. Record the data (in minutes and seconds) west of the farthest eastern meridian. Then add this value to the longitude of the other meridian to arrive at the longitude.
Step 1. Write down the coordinates
Typically, we note latitude first, followed by longitude, with both numbers to as many decimal places as possible. The more homes you include, the more accurate the location will be.
- You can use three formats to represent the latitude and longitude value in coordinates:
- Degrees (g, g°) - 49.5000° - 123.5000°.
- Minutes (g°m, m') - 49°30, 0', -123°30, 0'.
- Seconds (g°m's) - 49°30'00"N, 123°30'00"W.
- When tinkering with the latitude and longitude, the indicators "North", "South", "East" and "West" are exchanged for the negative values of the points south of the equator line.
Method 3 of 3: Using a Protractor
Step 1. Use the protractor method only during the day
Determining the latitude according to the sun only works when it is in full brightness. Look at the time on the clock or use the quadrant method (make a cross and place a stick on the ground at the southernmost end of a line between north and sun). It's "late" when the twig's shadow passes over the line.
Use a plumb bob to see if the stick is upright. The plumb line is an accessory made with a type of rope and a weight at the end and helps to determine the verticality of the lines
Step 2. Use a compass to find north and south
You can only calculate latitude and longitude if you know where north and south are. Mark both with lines on the ground and assemble the quadrant parallel to them.
Step 3. Make a quadrant (a cross) with two sticks
The horizontal stick must be on top of the vertical to be able to move up and down. Also, install a nail in each of the four corners of the cross - but without going through the material.
Center the protractor on the pivot of the cross and suspend the plumb from there
Step 4. Align the nails at the corners of the quadrant with the sun
When evening comes, align the nails on the horizontal stick with the sun. Don't look directly at him; use the shadows of the nails to find the correct position. Then move the quadrant arms up and down - so that the two shadows of the nails approach each other until they meet on the floor.
Step 5. Use the protractor to measure the smallest angle between the stick and the plumb
After aligning the horizontal stick, use the protractor to measure the vertical plumb to the part of the quadrant closest to it. Keep the horizon at 90° at this time.
Step 6. Understand that the time of year affects the accuracy of this calculation
The latitude and longitude reading will only be correct during the spring and autumn equinoxes, which run from September to March, respectively. If you take measurements on December 21st (in summer), subtract 23.45 degrees from the value. Otherwise, add 23, 45 degrees if you take measurements in winter (around June).
- Measurements are not entirely accurate, except at the spring and autumn equinoxes, because the Earth is tilted as it orbits the sun.
- Although you can use data from complex tables to determine the correct latitude and longitude on any given day, follow the spring and fall equinoxes to arrive at exact values. For example: if you take measurements in early May (mid-autumn), when the sun is directly over the equator (the autumnal equinox), when it is 23, 45° north of the equator, you would just have to add 11, 73° to the bill.
- You can also use a virtual calculator to simply determine latitude and longitude.
- Download mobile apps to determine latitude and longitude and use maps and virtual GPS devices.