I assume you are asking about very tiny drops of water, considerably
smaller than raindrops. If there are trees in the vicinity, these are
likely to be insect waste.
During a heavy cicada season I have walked under a tree laden with
cicadas and felt an almost constant drizzle of what must have been
cicada waste. They eat the leaves, absorb the nutrients, and excrete
Much more common though are droplets of honeydew, the waste of aphids:
"Aphids also produce a sticky material called honeydew.
Park your car underneath an aphid-infested tree and it
will be covered with tiny droplets of honeydew."
"The main problem with aphids is the sweet, sticky
honeydew they excrete, which then drips onto foliage
and anything under the plant or tree."
"The air above the alder thickets was filled with
myriads of the aphids in the winges stage, while the
trunks and leaves of the alders were covered with a
syrupy coating of honeydew (a sweet liquid which
those insects excrete profusely), and tiny droplets
of this material fell in a saccharine shower..."
I trust this provides the information you are seeking.
Google Search Strategy:
aphids OR insects OR cicadas "tiny drops OR droplets"