An instantaneous CCN (Cloud Condensation Nucleus) spectrometer
Abstract
A thermal gradient diffusion cloud chamber with a supersaturation field which increases along the path of the flow of sample is used as a cloud condensation nucleus (CCN) spectrometer. The CCN spectrum is derived from the final droplet distribution which has been determined to be related to the nucleus critical supersaturation based on routine calibration procedures using laboratory-produced monodisperse salt particles. The instrument is compared against a previously reported CCN counter on natural laboratory produced aerosol and against an absolute CN counter on the monodisperse aerosol. Preliminary results of atmospheric measurements are given. This device produces a CCN spectrum over the entire useful range of interest for cloud physics (0.01 to 1 percent supersaturation). More than 40 channels of resolution over this range are simultaneously provided. Data can be collected on a continuous basis for integration times as short as 2 seconds. The instrument has obtained data from four different airborne platforms, as well as from a mobile surface platform. The large number of channels allows the CCN spectrum to be displayed differentially instead of the usual cumulative display which is traditionally used in cloud physics.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- May 1989
- Bibcode:
- 1989STIN...8927150H
- Keywords:
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- Aerosols;
- Cloud Chambers;
- Cloud Physics;
- Condensation Nuclei;
- Spectrometers;
- Supersaturation;
- Calibrating;
- Clouds (Meteorology);
- Drops (Liquids);
- Temperature Gradients;
- Instrumentation and Photography