Rare noctilucent clouds seen over Northern Ireland

Jun 04, 2013

Armagh Observatory reports that rare noctilucent clouds were observed over Northern Ireland on the night of the 30/31 May. The so-called "night shining" clouds take various forms ranging from delicate feathery structures to streamers, ripples and waves, and usually have a silvery grey or electric-blue colour. They are a summer phenomenon which can only be seen at night and when the Sun is between approximately 5 and 15 degrees below the observer's horizon. At our latitudes this means that they often appear low towards the northern horizon during the summer months May to August, either after sunset or before sunrise.

The clouds are caused by sunlight reflecting off ice crystals very high in the Earth's atmosphere, in the region above the known as the . They typically lie at a height of around 80 kilometres. Any visible lower clouds appear dark, silhouetted against the luminous because they are in the Earth's shadow and not illuminated by the Sun.

Credit: Paul Evans, Larne, Northern Ireland, taken at 0025 BST Friday 31st May

The origin of noctilucent clouds remains a mystery. The most widely accepted explanation is that they comprise ice crystals that have condensed on tiny meteoric particles, which themselves have come from meteoroids or impacting the Earth's atmosphere.

One of the many puzzles surrounding noctilucent clouds is that they appear to be a relatively recent meteorological phenomenon, first described as a distinct cloud phenomenon by the and meteorologist Thomas William Backhouse in 1885. The first recorded observation of such clouds appears to be a note in the Observatory's climate archive made by the third director, the Revd Thomas Romney Robinson, who described "strange luminous clouds in NW, not auroral", seen around 10pm on 1st May 1850.

This video is not supported by your browser at this time.

For more information on these clouds, see article by astronomer John Butler Possible Observations of Noctilucent Clouds by Thomas Romney Robinson - PDF.

For Thomas Romney Robinson's early observation of these clouds, see May 1st 1850 - "strange luminous clouds in NW"

Explore further: NASA sees Typhoon Matmo making second landfall in China

add to favorites email to friend print save as pdf

Related Stories

Image: Station crew sees 'night-shining' clouds

Jun 27, 2012

(Phys.org) -- In both the Earth's Northern and Southern Hemispheres polar mesospheric clouds are at the peak of their visibility, during their respective late spring and early summer seasons. Visible from ...

2012 noctilucent cloud season begins

Jun 19, 2012

(Phys.org) -- Data from NASA's AIM spacecraft show that noctilucent clouds (NLCs) are like a great "geophysical light bulb". They turn on every year in late spring, reaching almost full intensity over a period ...

A noctilucent masterpiece

Aug 09, 2011

Night-shining “noctilucent” clouds create a magical glow in the night skies over Reykjavíc, Iceland in this beautiful photo by Örvar Atli Þorgeirsson, taken on August 6. In the ...

Measuring the seeds of noctilucent clouds

Apr 04, 2013

(Phys.org) —A constant stream of space debris flows toward Earth from the rest of the solar system. Large meteors can sometimes survive the intense friction and heat upon entering Earth's atmosphere, but ...

Meteor smoke makes strange clouds

Aug 08, 2012

Anyone who's ever seen a noctilucent cloud or “NLC” would agree: They look alien. The electric-blue ripples and pale tendrils of NLCs reaching across the night sky resemble something from another ...

Recommended for you

Fires in Central Africa During July 2014

8 hours ago

Hundreds of fires covered central Africa in mid-July 2014, as the annual fire season continues across the region. Multiple red hotspots, which indicate areas of increased temperatures, are heavily sprinkled ...

NASA's HS3 mission spotlight: The HIRAD instrument

18 hours ago

The Hurricane Imaging Radiometer, known as HIRAD, will fly aboard one of two unmanned Global Hawk aircraft during NASA's Hurricane Severe Storm Sentinel or HS3 mission from Wallops beginning August 26 through ...

Fires in the Northern Territories July 2014

Jul 23, 2014

Environment Canada has issued a high health risk warning for Yellowknife and surrounding area because of heavy smoke in the region due to forest fires. In the image taken by the Aqua satellite, the smoke ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

antigoracle
1 / 5 (2) Jun 04, 2013
Hmmmm... not one mention of global warming. Now that's even rarer.