Theoretical investigation of mixing in warm clouds – Part 2: Homogeneous mixing
Evolution of monodisperse and polydisperse droplet size distributions (DSD) during homogeneous mixing is analyzed. Time-dependent universal analytical expressions for supersaturation and liquid water content are derived. For an initial monodisperse DSD, these quantities are shown to depend on a s...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/9255/2016/acp-16-9255-2016.pdf |
| Summary: | Evolution of monodisperse and polydisperse droplet size distributions (DSD)
during homogeneous mixing is analyzed. Time-dependent universal analytical
expressions for supersaturation and liquid water content are derived. For an
initial monodisperse DSD, these quantities are shown to depend on a sole
non-dimensional parameter. The evolution of moments and moment-related
functions in the course of homogeneous evaporation of polydisperse DSD is
analyzed using a parcel model.<br><br>It is shown that the classic conceptual scheme, according to which
homogeneous mixing leads to a decrease in droplet mass at constant droplet
concentration, is valid only in cases of monodisperse or initially very
narrow polydisperse DSD. In cases of wide polydisperse DSD, mixing and
successive evaporation lead to a decrease of both mass and concentration, so
the characteristic droplet sizes remain nearly constant. As this feature is
typically associated with inhomogeneous mixing, we conclude that in cases of
an initially wide DSD at cloud top, homogeneous mixing is nearly
indistinguishable from inhomogeneous mixing. |
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| ISSN: | 1680-7316 1680-7324 |