Geomagnetic Dynamo

Earth's geodynamo operates in the liquid iron outer core (depth 2900–5100 km). The Coriolis force organizes convection columns parallel to Earth's rotation axis (Taylor-Proudman theorem), creating helical flow that stretches and amplifies magnetic field lines (the α-effect). The Ω-effect converts poloidal to toroidal field. Reversals occur every ~200–300 kyr on average but are irregular; we are currently overdue relative to average (last reversal 780 kya). Reversal takes ~1000–10,000 years.