In reality, there are no force lines and force fields. All made up word puzzles.

The magnetic force is a misinterpretation of the circular electric force. The field is a misinterpretation of force. Fields and forces must coexist with the matters/carriers.

There is no magnetic field around a current-carrying wire or coil. There are iron powders around a current-carrying wire or coil. 

The current in the wire induces nearby iron powders to become small magnets and connected together and form into a circle around the current is the precise mechanism. 

The so-called magnetic force is in fact circular electrostatic force carried by a circular current or concentric dipole rings in the magnet.

Due to sunlight is circling the earth, it induces a small current in the atmosphere from east to west around the earth. This is the true mechanism of earth magnetic force/field. This current moves at 1000 mile/h near the equator, accelerates to the poles, and causes polar lights.

This current causes compass to point to the north. Misinterprtatoned as molten iron core causes the earth's magnetic field.

I predict polar lights are swirling the same direction as sunlight moving around the earth.