Li explained the phenomenon: strange circular halo around the Sun.

Sun halo is an optical phenomenon that rarely occurs in nature and is not a circular rainbow as many people think. In fact, the brilliant halo around the Sun occurs when light is refracted multiple times at a 22-degree angle.

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"The strange sun" in Nghe An lunch on May 7.

Sun halo in Hue noon on 9/5.

Video of the Sun halo appeared in Hue by the people.

This phenomenon occurs due to the effect of the atmosphere. When temperatures rise, areas near the Sun often show hot air and cold air intersecting. Hot air filled with steam rose above the cold air and flew up into the sky. When the steam in the sky meets low temperature, it condenses into hexagonal prismatic ice crystals. When the sun shines on these flat crystals, it is strongly refracted to form a full-color rainbow-like circle around the Sun.

Round rainbow phenomenon.

This phenomenon also occurs at night with the Moon causing the "Moon halo" phenomenon.

Moon halo.

According to experts, when the sun or moon appears halo, it is expected to be rainy or windy in the coming days.