All About Space Astronomer Book - 2014 UK

(Frankie) #1

Glory
A glory is an optical phenomenon appearing in the clouds like a
projection of the observer’s head with a halo of light around it. It is
produced by light scattered back from its source by water droplets.
Glories can often be seen from mountains and tall buildings where
there are clouds of fog below the level of the observer. They are
associated with the “Spectre of the Brocken”, the enormously
magnified shadow cast by the low Sun on the under surfaces of
clouds. The name comes from the Brocken, the tallest peak in the
Harz mountain range in Germany where the phenomena is often
seen. From an aircraft you can often see a glory with the aircraft’s
shadow in the centre.


Airglow
Airglow is a faint glow caused by various processes mainly in the
upper atmosphere. During the day, scattered sunlight dominates
but at night, from a clear, dark site, airglow can impose limits on
the faintest objects that can be seen and photographed. The bluish
glow from airglow may be seen visually in a band 10 degrees above
the horizon where the atmospheric layer is thick. Lower down,
extinction dims the glow, rendering it harder to see.


Noctilucent Clouds
All normal clouds belong to the lowest part of our atmosphere,
known as the troposphere; the highest of these normal clouds are


[8] & [9] A display of night shining or noctilucent clouds over Selsey, England.

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Earth and sky

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