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The Brockenspectre and the Glory
Wed Oct 29, 2003
Listen in RealAudio 
Being high in the mountains has many rewards. Two not to be overlooked are the Brockenspectre
and the Glory. Hi, I'm Bryan Yeaton for The Weather Notebook.
The Brockenspectre is just the observer's shadow cast onto a mist or cloud, often seen
surrounded by a rainbow-like halo formed around the antisolar point. However, the shadow can
often be several meters high. The name derives from a prominent peak in Germany's Harz
Mountains the Brockenwhere mountaineers viewed the phenomenon in the early 1800s, and thought
it a haloed spirit beckoning them.
Viewing the Brockenspectre requires standing above or in front of a cloud, or falling mist,
with a bright sun directly behind you.
Sometimes, around the head of the Brokenspectre, is a ring of light known as the Glory. A
glory appears when light traversing the cloud scatters back to the observer's eye. They are
not rainbows, nor are they as easily explained.
In the returning sunlight, diffraction bends light slightly as it passes around the droplet
edges. The degree of bending depends on the light's wavelength relative to the droplet size.
Glories are 5 to 20 degrees across, with smaller droplets producing larger glories.
Diffraction produces light, dark, or colored bands by interference among overlapping light
waves. The Glory's center generally appears bright with darker, often iridescent, rings around
it. The more uniform the droplet-size, the more distinct the rings appear. Glories are often
seen from aircraft flying above the clouds.
The Brockenspectre and the Glory don't just appear at high altitudes. With proper lighting,
they can occur anywhere uniform-sized water droplets are suspended in the air.
Thanks to our contributing writer, meteorologist Keith Heidorn. The Weather Notebook receives
funding from The National Science Foundation, and Subaru.
Today's Links
The Glory
http://www.sundog.clara.co.uk/droplets/glory.htm
The Brockenspectre and Glory
http://www.meteoros.de/glorie/glorie_b.htm
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