This unusual multicoloured cloud was taken over Ethiopia.
http://apod.nasa.gov/apod/ap110824.html

Another iridescent cloud in Canada-
http://apod.nasa.gov/apod/ap110208.html

http://apod.nasa.gov/apod/ap090512.html


Other clouds

http://apod.nasa.gov/apod/ap071125.html

http://apod.nasa.gov/apod/ap050928.html

http://apod.nasa.gov/apod/ap040413.html

Very pretty arent they?