How airport runways are numbered

Watched The Simple Secret of Runway Digits from YouTube

Numbered based on compass bearing, abbreviated…but because it uses magnetic north those bearings sometimes change

Wind usually blows in the same or a couple directions, so usually works to build runways for those main wind directions

Coriolis Effect in both atmosphere and molten core

Earth is like a giant electromagnet –> magnetosphere

Iron cells are like miniature electromagnets

Earth’s magnetic field has dropped 10% in the last couple hundred years