A novel adiabatic-expansion-type cloud simulation chamber

A new cloud simulation chamber was built at the meteorological research institute (mri) to investigate the details of the fundamental processes of cloud formation. the mri cloud chamber was designed as an adiabatic-expansiontype cloud chamber covering temperatures from 30 to - 100°c,pressures from 1030 to 30 hpa,and an evacuation rates corresponding to ascent rates from 0 to 30 m s1. improvements to the cooling system and cloud characterization instrumentation distinguish the new facility from past devices of this type that are no longer functional (e.g.,the colorado state university dynamic cloud chamber),and the capabilities exceed those of any other active facility (e.g.,the aerosol interactions and dynamics in the atmosphere (aida) chamber) for covering a range of atmospheric conditions while reproducing approximately adiabatic parcel conditions. results from the preliminary experiments demonstrate the accuracy of coordinated pressure and temperature controls to reproduce cloud formation processes (both dry and wet adiabaticexpansion processes) and the ability of the chamber's instrumentation to measure aerosol,cloud droplet,and ice crystal characteristics. performance tests demonstrate the chamber's usefulness as a facility to investigate cloud droplet and ice crystal formation processes through the activation of various types of aerosol particles. © 2013,meteorological society of japan.