Instagram photo of Halo Effect
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Citizens
of Chelyabinsk, near Russia’s Ural mountains, were awed by a rare optical
illusion produced by ice crystals in the winter air on Tuesday.
“Weather in the Urals fell
to -23 to -25 Celsius. This led to the formation of tiny hexagonal ice crystals
in the air above, which cannot be seen by the naked eye. The sunlight refracts
through them, creating the halo effect,” regional meteorologist
Galina Sheporenko told TASS news agency
While
the scientists remained sanguine about the phenomenon, ordinary citizens filled
their social media accounts with hundreds of photos of the halo.
The
illusion is sometimes called a winter rainbow – using ice crystals for
refractions, just as the common ones use water droplets. The symmetrical
patches of light, tinged with red on the inside, are called mock suns, parhelia
or sundogs.
On average, such distinct halos are often reported several times a week across
the entire globe, and can occur even in relatively mild weather, providing the
air several kilometers above is sufficiently cold. A distinct halo was spotted
in Yamal in northern Siberia on Tuesday, barely noticeable one was photographed
in the eastern Siberian city of Irkutsk, and an impressive one was witnessed in
Saskatoon in Canada over the weekend.
“The
appearance of the halos can vary – from pillars to arcs to circles to blots. It
is very hard to predict when all factors will come together for one to appear,
but sometimes you can see several in one winter,”
said Sheporenko.
Another Instagram photo of Halo Effect |
Documented
descriptions date back to the ancient Greeks, and a halo features in William
Shakespeare’s Henry VI, where he mentions its appearance ahead of a key battle
in the War of the Roses.
Across
most world cultures, it was regarded as on omen, or harbinger of cold weather -
logically, as the crystals above required to create the halo, often descend
onto the ground as snow and rain. But Sheporenko says this is not the case this
time.
“The
frosty weather will only last a day or two, and then it will get warmer,”
promised the meteorologist.
Almost exactly two years ago, on February 15, 2013 Chelyabinsk, a city of 1.1
million people, hit the headlines after a blazing meteor flashed across the
sky, after impacting the atmosphere with the strength of over 20 Hiroshima
explosions. The 12,000 ton piece of space debris was the biggest object to
enter the Earth’s atmosphere since the Tunguska meteor in 1908.
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