Theory 18/Planetary Interiors
Dynamos Need a Flux Ratio
The claim
A planetary dynamo requires the ratio of heat flux to the adiabatic gradient to exceed a threshold, so a hot core alone does not generate a field.
01The mechanism
Convection requires the actual heat flux to exceed what conduction can carry; below that ratio the core is stably stratified regardless of temperature.
02Predictions
- P1Dynamo onset should track the ratio.
- P2Hot but subadiabatic cores should have no field.
03Refutation
Dynamo presence tracking core temperature would remove the flux ratio.