Nano/Micro-Structured Cloud Seeding Materials for Rain Enhancement

  • Haoran Liang

Student thesis: Doctoral Thesis

Abstract

Studies on harvesting water vapor in the atmosphere have drawn more attention recently, because the abundant water vapor present in the cloud still largely remains as an untapped source of fresh water. Cloud seeding, as one of the water harvesting methods, could play an essential role in increasing the utilization of such valuable resources. This thesis focuses on using nanotechnology to design and synthesize novel materials for cloud seeding applications as a means to utilize the atmospheric water resource, performing characterizations to verify their properties and structures, and evaluating their cloud seeding performance in a lab setting. Three different types of novel cloud seeding materials were synthesized over the course of the thesis that were designed to be effective in warm cloud and cold cloud conditions, respectively, including: core/shell NaCl/TiO2 (CSNT) particles with controlled particle size, with the ability to adsorb more water vapor (~ 295 times at low relative humidity, 20 % RH) than that of pure NaCl, which can deliquesce at lower environmental RH of 62 - 66 % than the hygroscopic point (hg.p., 75 % RH) of NaCl, and form larger water droplets ~ 6 - 10 times of its original measured size; bioinspired dual-layered shells/core microcrystal (reduced graphene oxide (rGO) – titanium dioxide (TiO2) /sodium chloride (NaCl), rGTNC) sharing similarities to the water-vapor-harvesting system of desert beetles, which could deliquesce at lower relative humidity (59 ± 3 %, RH) than that of NaCl (~ 75 % RH), and form larger water droplets ̴ 4-8 times its original areal size; porous composite of 3-dimensional (3D) reduced graphene oxide (rGO) and silica dioxide nanoparticles (PrGO-SN), which can initiate facile ice nucleation and growth starting from temperature as high as - 8 oC and 5 – 8 % RH supersaturation and sustain rapid ice crystal growth. These findings can shed lights on design and fabrication of more efficient cloud seeding materials and enable further understanding of the atmospheric water utilization.
Date of AwardMay 2020
Original languageAmerican English
SupervisorLinda Zou (Supervisor)

Keywords

  • Nanotechnology
  • cloud seeding materials
  • water droplet formation
  • ice nucleation and growth
  • water augmentation.

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