Magnetic Declination

What is Magnetic Declination?

Magnetic declination can be defined as the angle on the horizontal plane between magnetic and true north. This isn't consistent and keeps on changing relying upon the situation upon the world's surface and time. The Greek letter δ is recognized as the magnetic declination symbol and is otherwise called magnetic variation. 

The declination will be positive when the magnetic north is east of true north, and the declination will be negative when the magnetic north is west of true north. Different terms utilized are isogonic lines (when the lines along the declination are consistent) and agonic lines (when the lines along the declination are zero) 

Intrigued to learn more ideas identified with the magnetic field, have a look at more ideas underneath: 

  • Electromagnetic Induction 

  • Magnetic Flux 

  • Magnetic Field and Magnetic Field Lines 

  • Magnetic Poles and Their Significance 

There are three kinds of the north: True north, Grid north, and Magnetic north.

What is True North? 

True north can be defined as the direction towards the true north or the geological North Pole along the earth's surface. It is otherwise called geodetic north and is not the same as the magnetic north which is the direction pointed by the compass and from the grid north which is toward the path along the grid lines towards the north. 

What is Grid North? 

Grid north can be defined as the direction which is in northwards along the grid lines on a map projection. This term is utilized for route and the deviation of the grid north from the true north is less. 

What is Magnetic North? 

Magnetic north can be defined as the direction which is pointed by the compass needle in light of the earth's magnetic field. The deviation between the true north and the magnetic north differs from one to another as the earth's magnetic poles are not fixed as for its axis. 

Contrast Between Magnetic North and True North 

Following is the table clarifying magnetic north versus true north: 

Magnetic North: It is pointed by the compass needle in the north direction which is along the earth's magnetic field.

True North: It is the topographical north pointing towards the North Pole. 

What is Magnetic Dip? 

The magnetic dip can be defined as the edge by the earth's magnetic field lines made with the horizontal. It is otherwise called dip angle or magnetic inclination and was found by Georg Hartmann in the year 1544. At the point when the inclination is positive, it shows that the earth's magnetic lines are pointing downward in the northern half of the globe and when the inclination is negative it demonstrates that the earth's magnetic lines are facing upward in the southern side of the equator. 

In the year 1581, Robert Norman found a dip circle which is a technique to estimate the dip angle. Different terms utilized are isoclinic lines (when the contour lines are equivalent at the earth's surface) and aclinic lines (when the locus of the points are having zero dips). 

How to Calculate Magnetic Declination? 

From the declination calculator: The declination calculator is a simple method to figure the declination of any location on the earth. By giving the year, scope, and longitude of a given area, the calculator gives the declination based on magnetic reference field models. 

From a magnetic declination chart: A magnetic declination chart is a guide with the earth's magnetic fields accessible on it. 

From a compass: There are three kinds of bearing, they are true, magnetic, and compass bearing. A compass can be utilized to figure the declination as it is one of the mistakes of the compass and the other is magnetic variation. These three are connected by: 

T = M + V 

M = C + D 

T = C + V + D (which is a general condition relating compass and true direction) 


C is the compass bearing 

M is the magnetic bearing 

T is the true bearing 

V is the variation

D is the compass deviation 

V < 0, D < 0: this represents westerly variation and deviation 

V > 0, D > 0: this represents easterly variation and deviation 

Following is the best approach to compute compass bearing from true bearing: 

True bearing – variation = magnetic bearing 

Magnetic bearing – deviation = compass bearing 

Following is the best approach to compute true bearing from compass bearing: 

Compass bearing + deviation = magnetic bearing 

Magnetic bearing + variation = true bearing 

Presently it turns out to be evident that when we check for north direction utilizing a compass, the needle is really pointing towards the earth's magnetic north and not the true north.

FAQ (Frequently Asked Questions)

Q1. What is the Importance of Magnetic Declination?

Magnetic declination is a significant idea for the exact route. A compass will consistently point along the lines of magnetic power (which join on what are known as the magnetic poles). The angle between the power direction and the bearing of the geographic north pole is known as the declination. If a compass at your area is highlighting to the right of true north, declination is positive or east, and if it focuses on another side of true north, declination is negative or west. This is measured in terms of degrees and minutes east or west to show the direction of magnetic north from true north.

Q2. How to Calculate the Declination at any Given Place?

One way is to use declination maps. Tragically in light of secular variation, values of declination are continually evolving. When printed maps were the main method of getting this data, the values of declination were fairly outdated when the maps got to the overall population. As indicated by Nathaniel Bowditch, American practical navigator the magnetic declination can be said as the angle between the magnetic and geological meridians at any place.

Another way is to perform a prediction. This ought to be founded on an overall exact model of the profound streams. The model reflects a highly predictable pace of progress, and will, as a rule, be more precise than a guide, and never less exact.