I think the direction of the magnetic field taken is itself wrong. In the given figure the direction of magnetic field of earth is taken to be B and H and Z are its respective horizontal and vertical components. Now, according to this direction of the magnetic field. The North Pole of the needle of the magnetic compass will actually point towards the geographic South Pole which I have not heard of happening (though I could be unaware of such occurrence). I want to verify if this figure is actually correct. This figure is from my high school textbook. According to the convention given in textbook north magnetic pole is near the geographic North Pole and south magnetic pole is near the south geographic pole. The field lines emerge from the south magnetic pole and enter the north magnetic pole to form closed loops.