* The author is part of the community of readers of La Vanguardia

In La Vanguardia Readers’ Photos we can contemplate the iridescence next to the sun in these images captured in the sky of Vic, with the low sun reaching the horizon.

In these days of high clouds we have been able to observe this optical phenomenon similar to oil stains. Iridescent clouds are the result of sunlight diffracting through small ice crystals or water droplets.

In one image we see several and also ripples in the clouds. While in the second we see a similar rainbow, but next to the sun, a sun that was hiding over the horizon at sunset, to the right of the iridescence.

Iridescence is an optical phenomenon characterized as the property of certain surfaces in which the tone of light varies according to the angle from which the surface is observed, such as oil stains, soap bubbles, the wings of a butterfly and the playable side of the laser disc, whether CD or DVD.

Iridescence is caused by multiple reflections of light from multiple semitransparent surfaces, where subsequent phase changes and interference of the reflections modulate the light by amplification or attenuation of different wavelengths.

Depending on the angle at which the surface is illuminated, it will look different colors. Iridescence is very common in nature, we can easily see it in insects, birds and fish, and even in plants.