Airborne Observations of Convective Cloud Responses to Thai Formula8 (CaO-Based Powder) Cloud Seeding: Integrating Material Characterization and Thermodynamic Modeling with In Situ Observations

This study presents a multi-platform airborne empirical evaluation of an engineered thermodynamic reactive seeding agent, Thai Formula8 (a CaO-based powder), for warm convective cloud modification under the Thai Royal Rainmaking patent framework. Laboratory XRD and laser diffraction confirmed the reactive seeding agent XRD identified CaO as the dominant crystalline phase, accounting for 75.51% of the normalized crystalline-phase composition with a median particle diameter of 17.62 µm and a specific surface area of 4971.77 cm2/g. Calibrating these mineralogical fractions under cloud-base conditions (20 °C, 850 hPa) establishes a theoretical composite reaction enthalpy (ΔHFormula8,composite) of −1115.35 kJ/kg. Coordinated airborne campaigns deploying a Construcciones Aeronauticas S.A. (CASA) seeding aircraft at Cloud Base +2000 feet and a Super King Air profiling aircraft across three vertical layers investigated this thermodynamic mechanism across a 4-day dataset. In situ exothermic slaking at the mid-level core generated localized warming up to +0.92 °C, activating an artificial “thermodynamic pump”. This vertical suction conduit evacuated core liquid water content (ΔMLW down to −0.128 g/m3) and lofted moisture upward, accompanied by cloud-top accumulation (ΔTLW up to +0.145 g/m3) and a 2.4-fold (+140.5%) particle concentration surge. Rapid mass accumulation accelerated collision-coalescence, triggering warm-rain initiation via precipitation mass loading drag. This provides the first physics-based observational evidence for systematic, high-density thermodynamic cloud seeding.