Theory 59/Atmospheric Aerosols
Cloud Droplets Need a Size Ratio
The claim
Whether an aerosol activates into a cloud droplet is set by the ratio of particle size to the critical size at the ambient supersaturation, not by size alone.
01The mechanism
Köhler theory sets a critical radius that depends on supersaturation; particles below it stay haze while those above grow.
02Predictions
- P1Activation should track the ratio.
- P2Dry size alone should mispredict.
03Refutation
Activation tracking size would remove the supersaturation term.