A halo among the fibrous cirrus


Hanne Pernille Ryel
Location: Oslo, Norway
Date: 6 September 2013

Cirrus clouds appeared wispy and fibrous across the late summer sky as strong upper-level winds (more than 6 km or 20000 ft above the ground) carried the ice crystals. These ice crystals, specifically those with a columnar shape, bent the sun’s rays to form part of a 22-degree halo around the sun. The sun’s light enters one side of this columnar crystal, is refracted (bent) as it enters and bent again as it exits another side of the crystals resulting in a total bending of 22 degrees from how it enters, with a separation of the light into the colors of the visible spectrum (ROYGBIV).

Here is a diagram showing this refraction through a column ice crystal from the University of Illinois Urbana-Champaign’s online weather guide (http://ww2010.atmos.uiuc.edu/(Gh)/home.rxml)




Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s