Sun Halo: Rare Weather Phenomenon Spotted in Sweden
The 22 degree halo effect is caused by clouds floating thousands of feet above the ground.
Skiers at a resort in western Sweden were treated to a rare phenomenon when the sun appeared surrounded by a halo of light.
As it appeared low in the sky it was surrounded by a 22 degree halo of light at the Vemdalen ski resort.
Spectacular Sun halo display, with a 22° halo, parhelic circle, sundogs and a tangent arc as well as 44° parhelia (sundogs) and 46° halo, spotted in Vemdalen, Sweden on December 1, 2017 https://t.co/yUgpfe2heS pic.twitter.com/Sv2OyvlC9G
— Massimo (@Rainmaker1973b) December 2, 2017
The halos occur when sunlight refracts through a high band of cirrus clouds more than 20,000 feet above the ground.
These clouds, which are characterised as “thin and wispy”, contain million of individual ice crystals as water droplets have frozen in the air.
The sunlight bounces off these crystals making the waves change direction, this is refraction, and this gives the appearance that the sun has an extra halo of light surrounding it, EarthSky.com reported.
Scientists call it the halo because it has an approximate radius of 22 degrees from the sun.
They can also appear around the moon but as it absorbs and reflects light from the sun its rays are rarely strong enough for the halo to be visible.
