Precipitating condensation clouds in substellar atmospheres

Andrew S. Ackerman, Mark S. Marley

Research output: Contribution to journalArticlepeer-review

488 Scopus citations


We present a method to calculate vertical profiles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent diffusion and sedimentation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with results from previous methods. An adjustable parameter describing the efficiency of sedimentation allows the new model to span the range of predictions made by previous models. Calculations for the Jovian ammonia cloud are consistent with observations. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet. We find that precipitating cloud decks naturally account for the characteristic trends seen in the spectra of L-and T-type ultracool dwarfs.

Original languageEnglish (US)
Pages (from-to)872-884
Number of pages13
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - Aug 1 2001
Externally publishedYes


  • Planetary systems
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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