Tree leaves turn over
This old wives’ tale is actually valid. Before a storm hits, the humidity usually skyrockets, which makes the leaf stems on trees that drop their leaves in autumn go limp. Without their usual rigidity, those leaves show their undersides when the wind rustles them.
Bugs get less frisky
When barometric pressure drops before the rain, bugs lose interest in mating, according to a study in PLoS ONE. Researchers looked at the mating behaviour of different bug species – cucurbit beetles, potato aphids, and true army-worm moths – and all three species had similar reactions. When it felt like it was going to rain, the females put out fewer mating signals, and the males didn’t react as strongly to their pheromones. The bugs would still have sex if they were put near each other, but they’d get it over with quickly instead of going through their full mating rituals.
Birds might flee
In 2013, scientists tracking golden-winged warbler migrations were confused when the birds suddenly fled the Tennessee mountains, each travelling solo rather than in a flock. There was a storm brewing 900 kilometres away, but there was seemingly nothing that could have clued them in – the wind speeds, precipitation, and atmospheric pressure hadn’t changed. After the storm passed, the birds came back. Researchers figure the birds can sense sounds that are too low for humans to hear.