Circumscribed halo
The upper part of a circumscribed halo.
A circumscribed halo is a type of halo, an optical phenomenon that circumscribes a related phenomenon, the 22° halo centred on the sun.
When observed, a circumscribed halo is normally oval in shape and, at the points directly below and above the sun, lies tangential to the 22° halo. It forms when, as the sun rises, the upper tangent and lower tangent arcs extend into each other and close in on the 22° halo.[1] As the sun rises above 70° it essentially covers the 22° halo.[2]
A circumscribed halo is more intense in colour than the 22° halo. Like many other halos, it is reddish on the inner edge, facing the sun, and bluish on the outer edge. [2]
References
- ↑ Les Cowley (?). "Circumscribed Halo". Atmospheric Optics. Retrieved 2007-04-15. (includes a composite image of a circumscribed halo)
- 1 2 "Circumscribed Halo". Arbeitskreis Meteore e.V. Retrieved 2007-04-15. (includes a fisheye photo of the phenomenon)
See also
External links
- www.paraselene.de - HaloSim Computer simulations of a circumscribed halo.
- Atmospheric Optics - Circumscribed Halo - solar altitude - an animation showing how the shape of the phenomenon changes as the sun rises.
This article is issued from Wikipedia - version of the Tuesday, March 03, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.