News Weather

Find posts by keyword
Find posts by date

Print
Email
|

Weather Blog: Rain-less rainbow

by Gene Norman / KHOU11 News

khou.com

Posted on May 4, 2011 at 5:59 PM

Updated Wednesday, Oct 30 at 5:04 AM

Michelle Berryhill spotted this spectacular rainbow "around" the sun this afternoon in Houston.  A lot of you saw it, called or e-mailed me asking what it was.  Its a rarity called a sun dog; the fancy scientific name is parhelion.  You have to have just the right combination of ingredients to get one to appear in the skies over Houston.  We had them today.

Around 25,000 feet, a thin layer of ice crystals condense to form cirrus clouds.  A that level, the air is a bitterly cold 20 below zero!  But there is enough moisture to create hexagonal crystals.  As the sun's rays pass through the crystals, the light is bent or refracted like a prism.  If the crystals are scattered randomly, the bent light forms a halo around the sun.  If the crystals sink through the air, they become vertically aligned and the sunlight is refracted horizontally.  This gives the appearance of a vertical rainbow on either side of the sun.

Unfortunately, the ice won't melt and fall as rain.  Under the clouds, the air is extremely dry.  So when could we see some rain?  Maybe the latter part of next week.  Keep your fingers crossed and meanwhile enjoy nature's beauty, preferable to its fury.

Print
Email
|