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Abstract Comparisons of high‐resolution extended range CCN spectra measured at 100 m altitude with cloud and drizzle microphysics in the Rain in Cumulus over the Ocean (RICO) aircraft field project are presented. CCN concentrations,N_CCN, active at supersaturations,S, >0.1% showed positive relationships with cloud droplet concentrations,N_c, measured at intermediate (606–976 m) and very high altitudes (1,763–3,699 m). These correlation coefficients,R, progressively increased withSwhile the two‐tailed probabilities, P2, progressively decreased with S to < 10⁻⁶at 1.6%S. More important were the positive relationships betweenN_CCNactive atS < 0.1% and drizzle drop concentrations,N_d, at high (977–1,662 m), very high and high‐very high altitudes combined (977–3,699 m). All of these relationships were consistent for eight different cloud liquid water content,L_c, thresholds (forN_c) andL_cbins (forN_d) ranging from 0.0002 to 0.3 g/m³. Negative relationships between CCN modality and low altitude (76–475 m) cloudiness coupled with no relationship ofN_CCNactive at any S withN_cof these low clouds indicated a cloud effect on ambient aerosol. This is a demonstration of clouds causing bimodal aerosol.