Microlighters

OK every body is up to date with the magnetic declination. We here in PE is ( -28° 4' ( Fine ))

Gauteng is ( Magnetic declination: -18° 41' )
Cape Town (dorpie ) is ( Magnetic declination: -25° 14'
If you look at this site ( Please look here )

http://www.magnetic-declination.com

the Magnetic field strength is : 26621.0 nT
Up in Africa is Cairo : 43707.1 nT
so it goes up ( north ) : 56~ nT ( N)

Question ( How on EARTH is it possible that the Magnetic field strength can very
on earth???

The short answer is that the earths magnetic field is generated by a big solid blob spinning in a big molten blob incased in an oblong blob. So the classic image of the magnetic field lines looking like a highschool science class magnet is not exactly accurate. The shapes of the blobs (and probably their offset from the axis of rotation) determine field strenght. As you also know that they change with time and mag declination in displayed with a date with an average annual change. I recall there are older airfields with runway numbers that no longer match there current magnetic heading.

Oh, yes and we are overdue for a magnetic field reversal. Magnetic fields are weakening so scientist believe we are at the start of a reversal.

The further you move away from a magnet, the weaker the magnetic field would be. Hence the decreasing strength numbers when moving south.

Magnetic field strenght

Nice Biggles