Colorful clouds appear in Ho Chi Minh City before Vesak 2025 opening: Explanation from a scientific perspective

As Thanh Nien reported, this afternoon, while many Buddhists were worshiping Buddha's relics at Thanh Tam Pagoda (HCMC) and doing volunteer work to prepare for the 2025 United Nations Vesak Festival opening tomorrow morning, May 6, they were extremely surprised to see colorful clouds appear behind the Buddha statue.

Image of colorful clouds in the sky of Ho Chi Minh City this afternoon

PHOTO: BO NGUYEN

Talking about the phenomenon of iridescent clouds from a scientific perspective, Mr. Nguyen Anh Tuan, former head of the Ho Chi Minh City Amateur Astronomy Club (HAAC) described this as the appearance of colors in a cloud similar to what we see on oil slicks in a puddle. The phenomenon often occurs when clouds are located in an area near the apparent position of the sun or moon.

Mr. Tuan said that iridescent clouds are a diffraction phenomenon caused by individual water droplets or small ice crystals scattering light. "Iridescent clouds are not a rare phenomenon," Mr. Tuan informed.

Do iridescent clouds signal any weather phenomenon?

According to the literature, cloud iridescence is due to very uniform diffraction of light by water droplets (within 10 degrees from the sun) and due to first-order interference effects (beyond 10 degrees from the sun). It can extend up to 40 degrees from the sun.

If parts of the cloud contain small water droplets or ice crystals of similar size, their cumulative effect is seen as colors. The cloud must be optically thin so that most light rays encounter only a single droplet.

Coincidentally, in May last year, colorful clouds with unique shapes also appeared in the sky of Ho Chi Minh City.

PHOTO: CAO AN BIEN

Therefore, iridescence is mainly seen at the edge of clouds or in nearly transparent clouds, while newly formed clouds produce the brightest and most colorful iridescence. When the water or ice particles in a thin cloud are of a large proportion of the same size, the iridescence takes the form of a halo, a bright circular disk around the sun or moon, surrounded by one or more colored rings.

Experts say this is just a meteorological phenomenon and does not indicate any signs of upcoming weather developments.

This is not the first time people have seen colorful clouds in the sky of Ho Chi Minh City. On May 12 last year, a colorful cloud with a strange shape appeared in the sky of Ho Chi Minh City, causing a stir and being shared widely on social networks.

Source: https://thanhnien.vn/may-ngu-sac-xuat-hien-tai-tphcm-truoc-khai-mac-vesak-2025-ly-giai-duoi-goc-do-khoa-hoc-185250505182941592.htm