The CDC project investigated how droplet chemistry is affected by droplet growth processes, chemical reactions, and entrainment. Two different collection methods for cloud water were used: the Mohnen slotted rods, which collected a bulk cloud water sample, and the counterflow virtual impactor (CVI), which allowed size-selective droplet sampling. The CVI was used to determine droplet composition and concentration as a function of droplet size, and the morphology and composition of droplet residue particles and below-cloud aerosols were compared by electron microscopy.