Magnetic declination: the essence and practical application

The problem of orientation in space has always been very acute. Naturally, we are not talking about small distances, when you can take a landmark alone tree or a large stone. It is a question of considerable spaces, when the compass becomes the main assistant of the traveler. In this case, you can not do without the characteristics of such concepts as azimuth and magnetic declination.

Since school, we know that the azimuth is the angle that is formed between the direction of the selected object and the direction to the north, which indicates the arrow of the compass. However, the whole point is that the arrow of the compass points not to the North Pole, as it is commonly believed, but to the North Pole, whose position differs little from the geographical one, but changes with time (however, these changes occur so slowly that They can be neglected).

Thus, it turns out that using a compass a person finds a magnetic azimuth, and not a true one. If we are talking about a simple hiking trip, then such an error can be ignored, but ships in the sea, planes in the sky and a lot of other equipment should be oriented to the true azimuth, otherwise a catastrophe can occur.

The true azimuth, as follows from the above text, is the angle between the direction of an object or some other landmark and the direction to the geographic North Pole of the Earth. The difference between the magnetic azimuth and the true one was called the magnetic declination. It is generally accepted that if the magnetic declination has a direction to the east, then it is called "eastern". It is indicated in special tables by the sign "+". And if on the contrary, the magnetic declination is "western" and is indicated by the sign "-".

The notion of magnetic declination was introduced into scientific circulation a long time ago: the famous seafarer H. Columbus not only used it on his famous journeys to the shores of America, but also first drew attention to the fact that its magnitude varies depending on this or that territory.

Now there is no doubt that the numerical value of magnetic declination is not the same at different points of the globe. For example, in the city of Moscow it is +80, and for other regions it reaches more significant indicators. It is especially important to take into account the magnetic declination when working with geographic maps, when it is required to constantly translate the magnetic azimuth to the true azimuth, and vice versa.

Gunners to adjust their shooting use a special device - the bus. With the help of it, the exact direction to any landmark is determined, which is then used as the starting point for shooting. At its core, with the help of the bus, the magnetic azimuth is translated into the true azimuth.

Thus, the magnetic declination is the magnitude by which the magnetic azimuth differs from the true one. This knowledge is necessary not only for long expeditions, but also during artillery firing, as well as for the normal sailing of ships and aircraft flights.