title: Worldwide data sets constrain the water vapor uptake coefficient in cloud formation.
abstract: Cloud droplet formation depends on the condensation of water vapor on ambient aerosols, the rate of which is strongly affected by the kinetics of water uptake as expressed by the condensation (or mass accommodation) coefficient, αc. Estimates of αc for droplet growth from activation of ambient particles vary considerably and represent a critical source of uncertainty in estimates of global cloud droplet distributions and the aerosol indirect forcing of climate. We present an analysis of 10 globally relevant data sets of cloud condensation nuclei to constrain the value of αc for ambient aerosol. We find that rapid activation kinetics (αc > 0.1) is uniformly prevalent. This finding resolves a long-standing issue in cloud physics, as the uncertainty in water vapor accommodation on droplets is considerably less than previously thought.
authors: Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors: Tomi
authors: T
authors: Raatikainen
authors: Athanasios
authors: A
authors: Nenes
authors: John H
authors: JH
authors: Seinfeld
authors: Ricardo
authors: R
authors: Morales
authors: Richard H
authors: RH
authors: Moore
authors: Terry L
authors: TL
authors: Lathem
authors: Sara
authors: S
authors: Lance
authors: Luz T
authors: LT
authors: Padró
authors: Jack J
authors: JJ
authors: Lin
authors: Kate M
authors: KM
authors: Cerully
authors: Aikaterini
authors: A
authors: Bougiatioti
authors: Julie
authors: J
authors: Cozic
authors: Christopher R
authors: CR
authors: Ruehl
authors: Patrick Y
authors: PY
authors: Chuang
authors: Bruce E
authors: BE
authors: Anderson
authors: Richard C
authors: RC
authors: Flagan
authors: Haflidi
authors: H
authors: Jonsson
authors: Nikos
authors: N
authors: Mihalopoulos
authors: James N
authors: JN
authors: Smith