Phys. Rev. E 93, 023001 (2016)

Credit: © MARTIN HARVEY / ALAMY STOCK PHOTO

The increased frequency and severity of storms expected from global temperature rises could have a dramatic impact on both umbrella usage and tree populations. As storm data amasses, it seems that there is a critical wind speed that damages trees, regardless of the size or type. Emmanuel Virot and colleagues have provided insight into the physical origin of these somewhat counterintuitive observations.

Experimenting with beams of beechwood, Virot et al. showed that there is a critical radius of curvature that is needed to snap a wooden beam, which depends on the diameter and length, but not really on the elastic properties. And as there is a general relationship between a tree's height and its diameter — with a few assumptions — the critical wind speed can be written in a form that is dependent only on the tree's height.

But as this dependence is fairly weak, with the critical speed increasing by just 9% when the tree height is doubled, the critical wind speed at which trees break is roughly constant at 42 m s−1 — a value surely appreciated by fans of Douglas Adams.