When leaves so their undersides
There are a few weather related reasons for this observation.
The first deals with humidity and moisture. When a storm is approaching an area, there is an increase in humidity and moisture, which can soft the stalk (stem) of the leaf, causing it to turn over.
Another reason is that when leaves form, they form in a pattern of the prevailing wind, and when a storm comes near an area, the winds are different than normal, which can ruffle the leaves and cause them to flip over.
