Sun halo: A ring around the sun/ moon brings rain or snow. When the sun/ moon has a halo or ring around it, this is due to cirrus clouds in the higher altitudes. Cirrus and cirrostratus clouds typically proceed low pressure systems bearing moisture. These clouds also contain ice crystals which refract the light giving the impression of a ring. Expect a drastic change in the weather within 12 - 24 hours of a sun halo.
http://www.stalkingthewild.com/stw/weather.html

I saw a sun halo the other day and guess what? It rained that night. It's the first time I saw a sun halo and the only reason why I saw it was because we were staring at the sun during sungazing class. But apparently halos are pretty common.

What I want to catch before I go back to Singapore. Perfect sunsets are very common here.. Hope this can be seen.

Green flashes and green rays are rare optical phenomena that occur shortly after sunset or before sunrise, when a green spot is visible for a short period of time above the sun, or a green ray shoots up from the sunset point. It is usually observed from a low altitude where there is an unobstructed view of the horizon, such as on the ocean. Its explanation lies in refraction of light (as in a prism) in the atmosphere and is enhanced by atmospheric layering. Whilst we would expect to see a blue light, the blue is dispersed (this is why the sky is blue) and only the green light remains visible.
http://en.wikipedia.org/wiki/Green_flash