Quantifying moisture perturbations leading to stacked lenticular clouds

The origin of horizontal striations in lenticular clouds was qualitatively described by Richard Scorer as being due to a vertically layered moisture field, although the magnitude of the required moisture perturbations has not previously been quantified. Sensitivity tests using high-resolution numerical simulations of these clouds are used here to confirm Scorer’s hypothesis, and show that only minute and essentially unmeasurable variations in moisture with height are required to generate striations of the size observed in nature. Relative humidity (RH) perturbations of only ±0.25% can create an indentation into the cloud of approximately 170 m. RH perturbations of this scale are likely to be commonplace in nature, and are an order of magnitude smaller than the accuracy of standard measuring equipment.