What is the direction of vertical component of earth magnetic field is it upward or downward?
[Physics] Vertical component of Earth’s magnetic field
geomagnetismmagnetic fields
Related Solutions
Circulating neutral particles will not by themselves create a magnetic field. However, if the neutral particles are moving through an existing magnetic field, and the neutral medium is conducting, then the magnetic field will induce a current via the Lorentz force. That induced current will in turn create it's own magnetic field, which may enhance the existing magnetic field. If things work out right you have a self-reinforcing dynamo where motion thru the magnetic fields drives currents and those currents in turn support the magnetic field. However, there had to be some sort of "seed" field to get the thing started in the beginning.
Your question is related to the hairy ball theorem, which states that every continuous tangent vector field defined on a sphere must have a zero. Let's consider the tangent part of the magnetic field, $\mathbf{B}_T$: according to the previous theorem, there is a point on Earth where $\mathbf{B}_T = 0$, or in other words there is a point on Earth where the magnetic field is normal to the surface of Earth.
We just obtained a lone point where the geomagnetic field is normal, but why should there be a second point where this property is satisfied? Here, the symmetry of Earth comes into play: the geomagnetic field is roughly symmetrical around the plane of the equator (slightly turned to match the inclination of the magnetic poles), and here the magnetic field is almost tangent so the first zero can't be in this plane. Thus, the symmetrical point of our first point is another point where the geomagnetic field is normal to Earth.
If we changed the model of Earth's surface, the result would remain the same: indeed, the hairy ball theorem can be demonstrated for shapes similar from a topological point of view to a sphere.
Notice that in the second paragraph, I used a physical argument instead of a purely mathematical one: indeed, the result is not true in the general case. One can find a continuous vector field that is vertical on a sphere in only one point, see this question on Math.SE for example. Thus, generally speaking, the geomagnetic field could be vertical in only one point.
Best Answer
You confusion might well be the confusion experienced by many other students.
I have annotated the diagram to help with my explanation.
Near the geographic North Pole is what is called the magnetic North Pole.
The pole on a bar magnet (compass) which points towards the North is called the north (seeking) pole and they such poles are labelled $n$ in the diagram.
It is that pole which you call the north pole of a magnet.
By convention the direction of magnetic field lines is from the north pole of a bar magnet towards the south pole of bar magnet.
So in the Northern Hemisphere the magnetic field lines due to the Earth point into the Earth, ie the vertical component of the Earth’s field is downwards.
A complication arises if you want to liken the Earth’s magnetic field to that produced by a large bar magnet inside the Earth. Since the magnetic field lines due to the Earth are in a northerly direction the pole of the bar magnet inside the Earth nearest the magnetic north pole must be a south pole labelled $S$ in the diagram.