Search found 2 matches

by atoptics
Tue May 12, 2009 8:19 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: (Not) An Iridescent Cloud Over Ohio (2009 May 12)
Replies: 19
Views: 4838

(Not) An Iridescent Cloud Over Ohio (2009 May 12)

This is not an iridescent cloud nor are water droplets responsible. It is a halo, a circumhorizon arc (http://www.atoptics.co.uk/halo/cha2.htm) produced by refraction in hexagonal plate shaped ice crystals in cirrus. Note the structure parallel to the horizon and the structured gradation of color fr...
by atoptics
Mon Feb 23, 2009 3:54 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: An Etruscan Vase Moon Rising (APOD 2009 February 23)
Replies: 11
Views: 1974

Re: An Etruscan Vase Moon Rising (APOD 2009 February 23)

Miraged moonrises/moonsets of this type are created by warmer air beneath cooler air and not a temperature inversion - see
http://www.atoptics.co.uk/fz200.htm
also
http://www.atoptics.co.uk/atoptics/gfimform.htm

Les Cowley
http://www.atoptics.co.uk