Rainbow above Lucky Palms.
A rainbow is a multicolored stream of light occasionally seen in the skies.
The Sims 2[]
Rainbow spawners are available in Neighborhood mode.
The Sims 3: Pets[]
If a unicorn is standing still, eating hay, grazing, or drinking water, a rainbow may emanate from its horn.
The Sims 3: Seasons[]
Rainbows above the worlds have a 50% chance of appearing after a rain spell has ended. Such a rainbow is guaranteed to happen after a Reviving Sprinkle weather stone fairy event.[TS3:SN]
An exceptionally visible rainbow near Sunlit Tides.
The Sims 3: Into the Future[]
Small surface-level rainbows often appear above Oasis Landing Utopian Future dig sites.