The Randomness of Rain

The local spatiotemporal structure of rainfall is of critical importance to radar-based measurements of weather, erosion prediction, splash-based plant and fungal reproduction, and other droplet scale processes. Past studies using optical disdrometers (2DVDs) have observed structure in rain on the spatial scale of storms and rain cells, but little is known about the droplet scale due to tapering instrument resolution. In this work, we directly image raindrop arrival times and locations to investigate patterns and interactions on the centimeter scale. We analyze the droplet fall pattern through a pair correlation function and calculate a fractal dimension to determine spatial and temporal clustering. We hypothesis that raindrops will cluster as a function of drop size distribution and therefore storm type, convective or stratiform. We aim to apply our results on rain patterning at the smallest scale to understanding splash-based reproduction in early land plants.