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Comparative study of liquid carbon dioxide and silver iodide seeding effects on cumulonimbus clouds rainfall enhancement and hail suppression
Najafi, M.; Javanmard, S. & Mohammad-Hosseinzadeh, F.
Abstract
In this work, a comparative study of liquid
carbon dioxide versus silver iodide seeding effects on a
one-dimensional transient cumulonimbus cloud model is
made. The over-riding concern is to figure out the implications
of different seeding methods and agents for rainfall
enhancement and hail suppression in cumulonimbus
clouds. Based on the model results, it may be inferred that
for the liquid carbon dioxide seeding, the seedability
temperature limit is wider and the dynamic effects and
precipitations are stronger compared to those of the silver
iodide seeding. In addition, based on the model results, the
rainfall enhancement can augment to 52 % for liquid carbon
dioxide as the cloud top level increases. However, this
rainfall enhancement can augment to only 19 % in the case
of silver iodide seeding. Also, the model results show that
for clouds with cloud top level less than 7 km, the cumulative
rainfall for the point seeding is less than that for the
horizontal seeding, but for clouds with cloud top level
more than 9 km, the rainfall amount for the point seeding is
more than that for the horizontal seeding. The results also
show that there exist two threshold temperatures for the
silver iodide seeding methods. The model results also
indicate that the silver iodide seeding in the mixed clouds
can be used for the cloud seeding with the aim of hail
suppression. In general, the obtained results from this
model show to be comparable with the recorded data at rain
gauge stations.
Keywords
Homogenous and heterogeneous ice nucleation; Glaciogenic cloud seeding; Rainfall enhancement; Hail suppression
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