While rain drops do come in groups, rain itself is just rain, it doesn't come in groups.
Wet
In the rain was sung by The Dramatics...
it was from a movie called singing in the rain, it was sung by Gene Kelly
I believe the group was called Apollonia 6
Efe Pygmies
Blind Melon
I Can't Stand the Rain taken from a 1972 album of the same name by Ann Peebles. Later covered by a group called Eruption, and Tina Turner.
The names of the groups of clouds that can produce rain are nimbostratus and cumulonimbus. The nimbostratus clouds are the ones we see that become very dark and produce a lot of rain or snow. The cumulonimbus clouds are responsible for lighter rain and thunderstorms.
Water enters the group through absorption.
rain.... episodes 78, and the end of 87
Kandy Rain in week 1.
dancing in the rain