Quantifying ice nucleation by silver iodide aerosols
| dc.contributor.author | Demott, Paul Judson, author | |
| dc.date.accessioned | 2022-04-27T15:20:27Z | |
| dc.date.available | 2022-04-27T15:20:27Z | |
| dc.date.issued | 1990-05 | |
| dc.description | May 1990. | |
| dc.description | Also issued as author's dissertation (Ph.D.) -- Colorado State University, 1990. | |
| dc.description.abstract | Laboratory studies of artificial ice nucleating aerosols used for weather modification by cloud seeding have generally been inadequate for describing their complex action in the varied temperature, pressure humidity, and cloud conditions that can be encountered in the atmosphere. This study provides a quantitative framework for predicting ice formation by aerosol particles based on experiments which specifically target currently accepted mechanisms by which ice can form. A physical system for reproducing realistic atmospheric cloud conditions, the Colorado State University dynamic (controlled expansion) cloud chamber, is described. Physical simulations of adiabatic cloud formation and growth are demonstrated. Methodologies were also formulated to use the cloud chamber and other available instrumentation to isolate the action of ice nucleating aerosols by accepted primary ice nucleation modes. These methods were applied to the study of two chemically different silver iodide (AgI) - type aerosols, generated in the exact form in which they have been used for seeding natural clouds . The results were formulated as a function of basic thermodynamic quantities and particle size. An available one dimensional numerical cloud model with microphysical detail was adapted for the equivalent simulation of experiments performed in the cloud chamber. The model was utilized as a diagnostic tool to estimate water supersaturation in association with experiments and it was used for comparison of the predictions of new ice nucleus formulations with observations from generalized seeding simulations conducted in the cloud chamber. The nucleant and mode-specific formulations represent vast improvements compared to available formulations for "pure" AgI. The general implications of these new results were tested by using the model to simulate a few common seeding situations in the atmosphere, and the transferability of results was evaluated by modeling two actual seeding experiment s conducted in summertime cumuli . Within the limitations of the cloud model used, agreement with the atmospheric results was very good. The results of this study should be most useful for designing standard and better methods for the quantitative, study of ice nucleation by artificially generated and natural aerosols, and for evaluating cloud seeding methodologies and potential seeding effects using more complex microphysical - dynamic cloud models. | |
| dc.description.sponsorship | Sponsored by the National Science Foundation ATM-8519370 and ATM-8813345. | |
| dc.format.medium | reports | |
| dc.identifier.uri | https://hdl.handle.net/10217/234877 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation | Catalog record number (MMS ID): 991023630059703361 | |
| dc.relation | QC852 .C6 no. 466 | |
| dc.relation.ispartof | Atmospheric Science Papers (Blue Books) | |
| dc.relation.ispartof | Atmospheric science paper, no. 466 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.subject.lcsh | Ice nuclei | |
| dc.subject.lcsh | Atmospheric nucleation | |
| dc.subject.lcsh | Rain-making | |
| dc.subject.lcsh | Snowpack augmentation | |
| dc.subject.lcsh | Aerosols | |
| dc.title | Quantifying ice nucleation by silver iodide aerosols | |
| dc.type | Text | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). |
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