100px|A sky filled with many types of cirrus clouds
Cirrus clouds are atmospheric clouds characterized by thin, wispy
strands, often bunched into tufts. They range in color from white to a
faint gray and form when water vapor undergoes deposition at altitudes
above 5,000 m (16,500 ft) in temperate regions and above 6,100 m
(20,000 ft) in tropical regions. They also form from the outflow of
tropical cyclones or the anvils of cumulonimbus clouds. Since these
cirrus clouds arrive in advance of the frontal system or tropical
cyclone, it indicates that the weather conditions may soon deteriorate.
While they indicate the arrival of precipitation, cirrus clouds
themselves produce only fall streaks (falling ice crystals that
evaporate before landing on the ground). Jet stream-powered cirrus
clouds can grow long enough to stretch across continents, but they
remain only a few kilometers deep. When visible light interacts with
the ice crystals in cirrus clouds, it produces glories, sundogs, and
fire rainbows. Cirrus clouds raise the temperature of the air beneath
them by an average of 10 °C (18 °F). (more...)
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Today's selected anniversaries:
The Metropolitan Police of Greater London, originally headquartered in
Great Scotland Yard, Westminster, was founded.
Alouette 1, Canada's first satellite, and the first satellite operated
by a country other than the Soviet Union or the United States, was
The University of East Anglia was founded in Norwich, England, after
talk of establishing such a university in the city began as early as
the 19th century.
Gol Transportes Aéreos Flight 1907 collided in mid-air with an Embraer
Legacy business jet near Peixoto de Azevedo, Mato Grosso, Brazil,
killing 154 total people, and triggering a Brazilian aviation crisis.
Wiktionary's word of the day:
1. To deny oneself (something), to renounce or give up (a right, power,
claim, privilege or convenience).
2. To deny, to reject (something, for example a truth or a
Wikiquote quote of the day:
The truth is that my work — I was going to say my mission — is to
shatter the faith of men here, there, and everywhere, faith in
affirmation, faith in negation, and faith in abstention in faith, and
this for the sake of faith in faith itself; it is to war against all
those who submit, whether it be to Catholicism, or to rationalism, or
to agnosticism; it is to make all men live the life of inquietude and
--Miguel de Unamuno
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