Nimbus
What they look like
A small fluffy white cloud about the size of a pillow, with a pair of safety goggles perched on top and a tiny clipboard that floats next to her. When she gets excited she turns slightly pink like a sunset.
What makes them special
Nimbus wants to be a real scientist more than anything, so she does experiments everywhere she goes and writes down her hypothesis first, and she can rain exactly one drop at a time if she concentrates really hard.