Droplet Data Not New

Abstract

![Figure][1] CREDIT: JUPITERIMAGES Contrary to the implication in A. Cho's News of the Week story “Water droplets grow faster than expected” (24 April, p. [453][1]), the results are not new. The reported relationship between the volume of an isolated droplet and time to the power of 3/2 is a result of “Maxwellian” diffusion-limited growth ([ 1 ][2]), first examined by James Clerk Maxwell in the 19th century ([ 2 ][3]). Also well known is the reported reduction in growth rate when the droplets are crowded together, a situation commonly found in clouds. This reduction occurs because each droplet depletes the surrounding air of water vapor, effectively maintaining the local vapor pressure at a value near equilibrium ([ 3 ][4]). The transition observed by Sokuler and co-workers occurs when the droplet growth is no longer limited by local diffusion to isolated droplets, but by larger-scale diffusion to the ensemble. The 3/2 law is familiar to cloud physicists, and the linear growth rate of crowded droplets on a substrate is well known to researchers who study “breath figures” or aggregate growth on a surface ([ 4 ][5]). 1. [↵][6]1. Y.-S. Zou, 2. N. Fukuta , Atmos. Res. 52, 115 (1999). [OpenUrl][7][CrossRef][8] 2. [↵][9]1. J. C. Maxwell , The Scientific Papers of James Clerk Maxwell, Vol. 2 (Dover reprint, New York, 1890). 3. [↵][10]1. R. R. Rogers, 2. M. K. Yau , Short Course in Cloud Physics (Butterworth-Heinemann, Oxford, ed. 3, 1989). 4. [↵][11]1. D. Fritter, 2. C. M. Knobler, 3. D. A. Beysens , Phys. Rev. A 43, 2858 (1991). [OpenUrl][12][CrossRef][13][PubMed][14] [1]: pending:yes [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #ref-4 [6]: #xref-ref-1-1 View reference 1 in text [7]: {openurl}?query=rft.jtitle%253DAtmos.%2BRes.%26rft.volume%253D52%26rft.spage%253D115%26rft_id%253Dinfo%253Adoi%252F10.1016%252FS0169-8095%252899%252900025-3%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [8]: /lookup/external-ref?access_num=10.1016/S0169-8095(99)00025-3&link_type=DOI [9]: #xref-ref-2-1 View reference 2 in text [10]: #xref-ref-3-1 View reference 3 in text [11]: #xref-ref-4-1 View reference 4 in text [12]: {openurl}?query=rft.stitle%253DPHYSICAL%2BREVIEW.%2BA%26rft.aulast%253DFritter%26rft.auinit1%253DD.%26rft.volume%253D43%26rft.issue%253D6%26rft.spage%253D2858%26rft.epage%253D2869%26rft.atitle%253DExperiments%2Band%2Bsimulation%2Bof%2Bthe%2Bgrowth%2Bof%2Bdroplets%2Bon%2Ba%2Bsurface%2B%2528breath%2Bfigures%2529.%26rft_id%253Dinfo%253Adoi%252F10.1103%252FPhysRevA.43.2858%26rft_id%253Dinfo%253Apmid%252F9905351%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [13]: /lookup/external-ref?access_num=10.1103/PhysRevA.43.2858&link_type=DOI [14]: /lookup/external-ref?access_num=9905351&link_type=MED&atom=%2Fsci%2F325%2F5941%2F674.1.atom