Rainbow flag Alliance (ICA) designed an international co-op symbol and a flag for the first "Co-operators' Day," which was held in July 1923. After some experiments with different designs, a famous French cooperator, Professor Charles Gide, suggested using the seven colours of the rainbow for the flag. He pointed out that the rainbow symbolized unity in diversity and the power of light, enlightenment and progress. The first co-op rainbow flag was completed in 1924 and was adopted as an official symbol of the international cooperative movement in 1925. In 2001, the ICA's official flag was changed from a rainbow flag to a
Rainbow secondary rainbow is often visible. It appears about 10° outside of the primary rainbow, with inverse order of colours. The rainbow effect is also commonly seen near waterfalls or fountains. In addition, the effect can be artificially created by dispersing water droplets into the air during a sunny day. Rarely, a moonbow, lunar rainbow or nighttime rainbow, can be seen on strongly moonlit nights. As human visual perception for colour is poor in low light, moonbows are often perceived to be white. It is difficult to photograph the complete semicircle of a rainbow in one frame, as this would require