AgI Cloud Seeding Modeling for Hail Suppression of Cold Clouds

Abstract

In order to assess the performance of operational cloud seeding operations and achieve desirable results, application of numerical cloud model is one of the most important tools. In this paper, effects of silver iodide (AgI) cloud seeding on hail fall have been examined using one dimensional time dependent numerical cloud model. We included 32 microphysical processes with six water substances including water vapor, cloud droplet, cloud ice, rain, snow, and hail (graupel) for natural precipitation and 3 microphysical processes for cloud seeding parameterization. The model has been executed and it is concluded that as AgI introduced into the cloud resulting in graupel/hail mixing ratio reducing about %53. Heterogeneous nucleation of AgI enhanced the cloud ice, therefore snow increased and rainfall enhanced by melting of snow and cloud ice. On the other hand, cloud ice consumed to produce snow and they did not grow up to reach graupel/hail size, consequently the processes that related to growth of graupel/hail decreased strongly.

Comparative study of liquid carbon dioxide and silver iodide seeding effects on cumulonimbus clouds rainfall enhancement and hail suppression

“…4, P denotes microphysical processes. This work contains 42 microphysical processes the same as those of Javanmard and Karimpirhayati (2012). For more details refer to Section D in the Appendix.…”

“…Sounding data of the present work are adjusted to produce clouds with different CTLs to investigate sensitivity of rainfall enhancement to different CTLs and seeding agents. This work uses a one-dimensional transient cumulonimbus cloud model with single-moment bulk parameterization (Javanmard and Mohammad-Hosseinzadeh 2012;Javanmard and Karimpirhayati 2012) to compare sensitivity of the seeding effects to CTLs, existence of mixed phase, and seeding methods for the two seeding agents of LCO 2 and AgI. The work of this project was conducted at the department of mechanical and aerospace engineering in Tehran Science and Research branch of Islamic Azad University in Iran during 2011-2013.…”