Invasion From The Skies

Falling from the sky,
of me there are plenty.
We hit the ground in waves
and immediately go into action.
In the distance you can hear
the beating of a drum,
as we rhythmically land on an old tin roof.
Once we are together nothing can stop us.
Though we have no set destination,
we can go where ever we want.
We can flow like a river
and could destroy anything in our path.
In full force we are invincible,
yet we are usually gentle and helpful.
We could destroy the world if we desired,
but would rather only help you with your garden.
We can appear on sunny days or in the dark.
Sometimes we are cool and sometimes warm.
Our friend, the wind, is our greatest ally.
He brings us to different parts of the world
where we can begin our invasion,
if we so desire.
We are raindrops from the skies.