Weather Word Wednesday : Glory
Have you ever been out hiking and looked down on a waterfall, surprised to see a round, rainbow colored halo? Or perhaps you’ve looked off towards a bank of clouds, with the sun at your back, and seen the same colored halo? If so, you’ve seen what meteorologists call a Glory.
Essentially, a Glory is “one or more sequences of faintly colored rings of light that can be seen by an observer around his own shadow cast on a water cloud (a cloud consisting mainly of small, uniform sized water droplets). It can also be seen on fog and exceptionally on dew.” The glory can only be seen when the observer is directly between the sun and cloud of refracting water droplets.
Glories are not completely understood. The colored rings of the glory are caused by two-ray interference between “short” and “long” path surface waves – which are generated by light rays entering the droplets at diametrically opposite points (both rays suffer one internal reflection). Glories are often seen in association with a Brocken spectre, the apparently enormously magnified shadow of an observer, cast (when the Sun is low) upon the upper surfaces of clouds that are below the mountain upon which he or she stands. The name derives from the Brocken, the tallest peak of the Harz mountain range in Germany. Because the peak is above the cloud level, and the area is frequently misty, the condition of a shadow cast onto a cloud layer is relatively favored. The appearance of giant shadows that seemed to move by themselves due to the movement of the cloud layer (this movement is another part of the definition of the Brocken Spectre), and which were surrounded by optical glory halos, may have contributed to the reputation the Harz mountains hold as a refuge for witches and evil spirits.
The next time you have your back to the sun and clouds at your front, or are up high with clouds below, try and find a Glory on your shadow. If you have a camera with you, and see a Glory, send us a snapshot!
Source : Wikipedia