She was not only the godess of rainbows, but also a messenger for the gods, especially for Hera. She, (in an echo of the Biblical story of Noah), as a godess of rainbows represents the pact between men and gods and the end of the storm.
A gorgeous piece of art. The rainbow in her hands contrasts her domain as the goddess of rainbows beautifully and she looks so serene and beautiful. I love the background you put her in, she is commonly depicted as a messenger goddess that travels from one end of the world to another at the speed of wind. Sometimes she is shown as a goddess of the sea and sky. You represent those aspects beautifully, the vast ocean below and the clouds in the sky behind her.