- Education and Science
What Causes a Ring Around the Sun?
I saw a ring around the sun.
Luckily, the people with me at the time were scientist-types and were able to explain to me what causes it.
It was really quite amazing to witness, and lasted for about half an hour.
The sky was a hazy blue, and the sun appeared to have a rainbow all the way round it. Luckily, I had my camera with me and was able to snap a couple of shots of it.
I found out later I could have damaged my camera by pointing the lens straight at the sun, but I got away with it this time, presumably because the sun itself was slightly 'hazed out' by the thin covering of high white cloud which was barely noticeable in the sky.
Taking the photo wasn't that easy either, as I had to guess where the ring was and just point the camera in the general direction.
This is the best of the bunch, and I like the seagull flying in the distance.
So, what causes a ring around the sun?
Here comes the technical bit.
The high thin clouds we barely noticed are called cirrus clouds, and those clouds are made up of millions of tiny ice crystals.
Cirrus clouds are very high clouds, actually forming in the troposphere, 3 - 6 miles above Earth, where the temperature hovers around minus 30° to minus 35°C (-31°F).
The crystals are miniature prisms that reflect and spread white light into the colors that make up white light, which are all the colors of the rainbow.
The sun refracts through those crystals which are hexagonal in shape, with most of the refracted light heading back towards the sun, but with a substantial amount heading towards us on the ground.
Hexagons are six-sided shapes, and the light is deflected not once, but twice as it hits off different angles on the prism.
Light cannot be refracted at angles less than 22°, and this is what forms the circle, all of it being exactly 22° from the sun.
For this reason, rings round the sun are often referred to as 22° halos.
What does a ring around the sun mean?
It's generally accepted to be a harbinger of rain.
The presence of those cirrus or cirrostratus clouds generally means a warm front is moving in, bringing with it precipitation.
More than just an old wives tale, a halo round both the sun and moon really does mean rain is coming, according to meteorologists, and it is nice to get a warning of these things now and then.
Did the rain come?
Not for a while after. It stayed mostly sunny and dry for the next 4 hours, but the wind gradually rose.
I sat and watched the fishing boats scurrying into the shelter of the harbour. No doubt they listened to the warnings showing up on their radars or perhaps the shipping forecast.
I had a washing out to dry on the line, thinking to myself what a grand day it was for drying clothes, with the wind and the sun, even though the wind was rising still.
About half an hour afterwards the rain started, and the wind rose to storm force, and the rain was relentless all night.
This just goes to prove that a ring round the sun is indeed a warning of rain to come, even though I'd just expected a shower and not a storm.