July 4, 2020

Ring around the sun

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IMG_0789Did anyone notice the spectacular enormous ring around the sun today (8)?

I got a frantic call from a friend to go outside and take a look. I did.

Wow. I have seen it before but never as spectacular as this.

Out came my camera and these are the results – well the three best ones of many I snapped. I couldn’t get a shot of the whole circle because of the trees and buildings at my home in George Town.IMG-20130508-00014

[Note: the photo showing almost he whole halo was sent in by a reader – Thank you Garry]

However, they are quite common and are called a “halo” by scientists.

Going on to the website Earth Sky this is what they have to say about it.

IMG_0784 Ring sunWhat makes a halo around the sun or moon?

“Halos around the moon – or sun – are a sign of thin cirrus clouds drifting high above our heads. They are a sign of nearby storms.”

There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads.

IMG_0780 sun ringThese clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own particular halo, made by their own particular ice crystals, which are different from the ice crystals making the halo of the person standing next to you.

Because moonlight isn’t very bright, lunar halos are mostly colorless, but you might notice more red on the inside and more blue on the outside of the halo. These colors are more noticeable in halos around the sun. If you do see a halo around the moon or sun, notice that the inner edge is sharp, while the outer edge is more diffuse. Also, notice that the sky surrounding the halo is darker than the rest of the sky.

Bottom line: Halos around the sun or moon happen when high, thin cirrus clouds are drifting high above your head. Tiny ice crystals in Earth’s atmosphere cause the halos. They do this by refracting and reflecting the light. Lunar halos are signs that storms are nearby.

At Les Crowley’s atopics it says:

“Ice halo displays range from the familiar circle around the sun or moon to rare and prized events when the whole sky is webbed by intricate arcs.

“Tiny ice crystals in the atmosphere create halos by refracting and reflecting light.

“Halos bestow a delicate beauty to the skies and tell us about the crystals inhabiting the clouds.”

Halo sizes

The most common is the 22° radius circular halo. It is easily found in the sky. Stretch out your arm and spread your fingers wide. The distance from the thumb to the tip of the little finger is then about 20°. Cover the sun with the thumb and the 22° halo will be near the tip of the small finger.

For more on this story go to:

http://earthsky.org/space/what-makes-a-halo-around-the-moon

 

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