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Cirrus clouds are atmospheric clouds characterized by thin, wispy strands, often bunched into tufts. They range in color from white to faint gray and form when water vapor undergoes deposition at altitudes above 5,000 m (16,500 ft) in temperate regions and above 6,000 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, they indicate that the weather conditions may soon deteriorate. While they can indicate the arrival of precipitation, cirrus clouds themselves produce only fall streaks (falling ice crystals that evaporate before landing on the ground). Jet streams can stretch cirrus clouds across continents, but the clouds will remain only a few kilometers deep. When visible light interacts with the ice crystals in cirrus clouds, it can produce glories, sun dogs, and fire rainbows. (Full article...)

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Did you know ...

Actual 3:2 spin–orbit resonance of Mercury

... that many fictional depictions of Mercury feature the now-disproven belief that it always points the same side towards the Sun (actual orbital resonance pictured)?
... that Frankie Saluto was a member of the Ringling Giants, a dwarf baseball team that raised money for charity?
... that one music critic said that despite being "noisy, banal, fundamentally insincere", Dmitri Shostakovich's symphonic poem October was nonetheless "enjoyable trash"?
... that Centre College president William C. Young awarded degrees to three of his half-sisters in 1891, as they had completed the requirements forty years earlier?
... that after four years in the making, the Minimal BASIC standard was described as "more a toy than an actual language"?
... that the captain of CSS Pontchartrain was twice detached from the ship to fight in land battles?
... that Adolphe Jacquies was arrested for publishing a poem?
... that the game of slosh shares the name with a English batter and sausage dish?

In the news

Hassan Sheikh Mohamud

Hassan Sheikh Mohamud (pictured) is elected as President of Somalia.
In the United States, ten people are killed in a mass shooting at a supermarket in Buffalo, New York.
Ukraine, represented by Kalush Orchestra with the song "Stefania", wins the Eurovision Song Contest.
Mohamed bin Zayed Al Nahyan inherits the Emirate of Abu Dhabi and becomes President of the United Arab Emirates after the death of Khalifa bin Zayed Al Nahyan.

On this day

May 21

Charles Lindbergh and the Spirit of St. Louis

1403 – King Henry III of Castile sent an embassy to the Timurid court to discuss a potential alliance against the Ottoman Empire.
1911 – Mexican president Porfirio Díaz and the revolutionary Francisco I. Madero signed the Treaty of Ciudad Juárez to end hostilities between each other's forces, concluding the initial phase of the Mexican Revolution.
1927 – Aboard the Spirit of St. Louis, American aviator Charles Lindbergh (pictured) completed the first solo non-stop transatlantic flight, flying from Roosevelt Field near New York City to Paris–Le Bourget Airport.
1946 – While working with a mass of plutonium known as the demon core, Manhattan Project physicist Louis Slotin accidentally exposed himself to a lethal dose of hard radiation.
2014 – A Taiwanese man carried out a stabbing spree on a Taipei Metro train, killing four people and injuring 24 others.

Luis Fajardo (d. 1617)
Anne Walter Fearn (b. 1867)
Leonidas Vasilikopoulos (b. 1932)

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Today's featured picture

Lucy Arbell (8 June 1878 – 21 May 1947) was a French mezzo-soprano whose operatic career was mainly centred in Paris and who was particularly associated with the composer Jules Massenet. She created the roles of Queen Amahelli in Massenet's opera Bacchus, inspired by Greek mythology, in which the gods appear in human form in ancient India to attempt to persuade the people away from the pervading Buddhist influence. This photograph, taken by the French photographer Nadar, depicts Arbell in the role of Queen Amahelli for the 1909 premiere of Bacchus at the Palais Garnier in Paris.

Photograph credit: Nadar; restored by Adam Cuerden

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