Toroh: An Extreme Orographic Convective Event Physical Modelling and Implications for Persistent Geological Anomalies

Abstract

We introduce the toroh -- formally designated an Extreme Orographic Convective Event (EOCE) -- as a previously uncharacterised class of atmospheric hazard distinct from downbursts and conventional hailstorms. The toroh is a coherent hydraulic ice-piston formed when a convective system with anomalously narrow drop size distribution (mu ~ 20) undergoes explosive secondary ice production via the Hallett-Mossop mechanism, triggered by marine iodine ice-nucleating particles injected by a vortex or orographic resonance with an inselberg (Planalto Mirador, SC, Brazil). The piston collapses coherently into canyon terrain, producing a two-phase acoustic signature, seismic tremor M_L ~ 2-3, and a diagnostic erosion scar with zero fine-grained matrix. Piston cohesion is justified by ice sintering kinetics: tau_p ~ 0.04 s << tau_sint = 1-10 s, and sintered tensile strength ~10^4 Pa exceeds aerodynamic fragmentation pressure ~10^3 Pa. We propose EOCE as a candidate mechanism for four persistent geological anomalies: (1) erosional amphitheatres in resistant bedrock; (2) heavy mineral concentration in canyon lag deposits; (3) spatiotemporal heterogeneity of the Great Unconformity, incompatible with uniform Snowball Earth glaciation; (4) the nutrient pulse preceding the Cambrian Explosion. In pristine pre-industrial conditions, EOCE frequency is estimated at 1-10 per century per canyon -- sufficient for independent geomythological encoding in ~18 culturally isolated traditions. The Adams Event (Laschamp, ~42 ka) amplified this baseline 10-100x; 20th-century tetraethyl-lead aerosols suppressed it below observational threshold. A 3D anelastic bin-microphysics model and testable predictions are presented. Code: https://github.com/reinaldohaas/toro-model