ISSN:
1420-9136
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Geologie und Paläontologie
,
Physik
Notizen:
Abstract Condensed water in a vertical column is related through continuity equations to the updraft speed, column depth, height of the condensation level, and strength of microphysical processes. When the ratio of updraft to characteristic particle fall speed is small, as in stratiform rain, the mass of precipitation in the steady state is proportional to the product of that ratio, column depth, and condensation function. When the ratio is only slightly above unity, two water content regimes are defined by continuity equations. The regime of large water content, an extension of the case described above, occurs when the condensation level is low and when there is rapid conversion of cloud to precipitation. Another regime characterized by a water mass about one-third as large (or less), and absence of precipitation at the ground beneath the updraft column, appears if the condensation level is high enough or cloud conversion slow enough. When the ratio is large, the total water content is usually much smaller than when updrafts and fall speeds are similar, and declines slowly toward a limiting value with increasing ratio. As updrafts intensify, precipitation is more limited near the top of the column, with increasing depth and amount of cloud beneath. In the limit of very fast updraft and weak cloud conversion process, the condensate profile is simply the profile of cloud in air risen from the condensation level without conversion of cloud to precipitation. These findings contrast substantially with those presented by Sulakvelidze,et al., who proposed that the water mass associated with strong updrafts increases with the square of the updraft speed. The difference in results is traced to its origins in different model assumptions.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01592969
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