How to determine the coordinates?
There is a coordinate system on globes and geographical maps. With its help, you can put any object on the globe or map, as well as find it on the earth's surface. What is this system, and how to determine the coordinates of any object on the surface of the Earth with its participation? We will try to tell about it in this article.
Geographic latitude and longitude
Longitude and latitude - geographical concepts, which are measured in angular values (degrees). They serve to indicate the position of any point (object) on the earth's surface.
Geographic latitude - the angle between the plumb line at any particular point and the equatorial plane (zero parallel). Latitude in the southern hemisphere is called the southern, and in the northern hemisphere - northern. May vary from 0∗up to 90∗.
Geographic longitude is the angle that is drawn up by the plane of the meridian at a certain point to the plane of the initial meridian. If the countdown of longitude goes east of the initial Greenwich meridian, then it will be east longitude, and if westward, it will be west longitude.Longitude values can be from 0∗up to 180∗. Most often, on globes and maps, meridians (longitude) are indicated when they intersect with the equator.
How to determine your coordinates
When a person gets into an emergency, he should, above all, be well versed in the terrain. In some cases it is necessary to have certain skills in determining the geographic coordinates of their location, for example, in order to transfer them to rescuers. There are several ways to do it in the best possible way. We give the most simple of them.
Determination of the longitude of the gnomon
If you go on a trip, it is best to set the clock to Greenwich time:
- It is necessary to determine when it will be noon GMT.
- Stick a stick (gnomon) to determine the shortest sun shadow at noon.
- Notice the minimum shadow cast by the gnomon. This time will be the local noon. In addition, this shadow at this time will point strictly to the north.
- Calculate at this time the longitude of the place where you are.
Calculations are based on the following:
- since the Earth makes a complete revolution in 24 hours, therefore, 15∗(degrees) it will take 1 hour;
- 4 minutes of time will be equal to 1 geographical degree;
- 1 second of longitude will be equal to 4 seconds of time;
- if it is noon before 12:00 GMT, this means that you are in the Eastern Hemisphere;
- if you notice the shortest shade later than 12 hours GMT, then you are in the Western hemisphere.
An example of the simplest calculation of longitude: the shortest shadow was cast by the gnomon at 11 hours and 36 minutes, that is, noon came 24 minutes earlier than in Greenwich. Based on the fact that 4 minutes of time are equal to 1∗longitude, we calculate - 24 minutes / 4 minutes = 6∗. This means that you are in the Eastern Hemisphere at 6∗longitude
How to determine the latitude
The determination is made using a protractor and plumb. For this, a protractor is made of 2 rectangular slats and fastened in the form of a compass so that the angle between them can be changed.
- The thread with a weight is fixed in the central part of the protractor and plays the role of a plumb.
- With its base, a protractor is aimed at the Polar Star.
- 90 are subtracted from the angle between the protractor’s plumb and its base∗. The result is an angle between the horizon and the Polar Star. Since this star is only 1∗deviated from the axis of the world pole, then the resulting angle will be equal to the latitude of the place where you are at this time.
How to determine geographic coordinates
The easiest way to determine geographic coordinates, which does not require any calculations, is:
- Open up
- Find there the exact place;
- the card moves the mouse, is removed and is approached with the help of its wheel
- Find a locality by name using the search.
- Click on the right place with the right mouse button. Choose from the menu that opens the desired item. In this case, "What is there?" In the search line, the geographical coordinates will appear at the top of the window. For example: Sochi - 43.596306, 39.7229. They denote the geographical latitude and longitude of the center of this city. So you can determine the coordinates of your street or house.
On the same coordinates you can see the place on the map. Only swap these numbers can not be. If you put longitude in the first place, and then latitude, then you risk being elsewhere. For example, instead of Moscow you will go to Turkmenistan.
How to determine the coordinates on the map
To determine the latitude of the object, you need to find the closest parallel to it from the equator. For example, Moscow is located between the 50th and 60th parallels. The closest parallel from the equator is the 50th. To this figure is added the number of degrees of the arc of the meridian, which is from the 50th parallel to the desired object. The number is equal to 6. Therefore, 50 + 6 = 56. Moscow lies on the 56th parallel.
To determine the geographic longitude of the object, find the meridian where it is located. For example, St. Petersburg lies to the east of Greenwich. Meridian, this distance is zero meridian at 30∗. This means that the city of St. Petersburg is located in the Eastern Hemisphere at a longitude of 30∗.
How to determine the coordinates of the geographical longitude of the desired object, if it is located between the two meridians? At the very beginning, the longitude of that meridian, which is located closer to Greenwich, is determined. Then to this value it is necessary to add such a number of degrees, which is the distance between the object and the meridian closest to Greenwich on the arc of a parallel.
Example, Moscow is located in the east of the meridian 30∗. The arc of parallel between it and Moscow is 8∗. This means that Moscow has east longitude and it is 38∗(VD).
How to determine your coordinates on topographic maps? The geodesic and astronomical coordinates of the same objects differ on average by 70 m. The parallels and meridians on topographic maps are the internal frames of the sheets. Their latitude and longitude are written in the corner of each sheet. The sheets of maps of the Western Hemisphere are marked in the northwest corner of the frame “West of Greenwich”. On the maps of the Eastern hemisphere, respectively, will be marked "East of Greenwich."