A bucket full of water has a large pebble at the bottom. Every so often a coloured circle appears on the surface of the water, expanding rapidly and changing colour, and then disappearing. Every so often a drop of water lands on a bucket of water. Instead of merging into the water, it splits up into little drops that run around on the surface of the water. When it is very cold, rain-drops hitting your windscreen seem to splatter out into irregular shapes.
Astronauts make big wobbly drops of water float around in a space-craft.
Sometimes there is a coloured halo around the sun or the moon. Less commonly there is also a similar halo around the zenith. This halo just touches the one around the sun. Sometimes you see two concentric rainbows, the outer one fainter than the inner. Much less often you see non-concentric rainbows.