A sun halo seen from a Housing Board block near Guillemard Road at about 12.15pm yesterday. The weather phenomenon occurs when thin clouds are so high in the sky that the water in them consists of ice crystals rather than droplets. These crystals act like tiny prisms, reflecting and refracting light in a way that creates what appears to be a ring around the sun.

Yesterday's sun halo was visible from locations across eastern Singapore such as Tampines, Simei and Ubi around noon.

A less distinct halo was seen three weeks ago, near the Merlion.

The National Environment Agency said previously that it is difficult to forecast the precise location of ice crystals in the atmosphere, which would determine where the halo can be seen from the ground.

It also said that while it is safe to look at the halo itself with the naked eye, it is dangerous to look at the sun directly without proper protection.