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: TRMM Satellite calculates Hurricanes Fay and Gonzalo rainfall

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

Tropical Depression 9 forms in Gulf of Mexico

12 hours ago

Tropical Depression Nine formed over the western Bay of Campeche, Gulf of Mexico and is forecast to make a quick landfall on Mexico's Yucatan Peninsula. NOAA's GOES-East Satellite captured the birth of the ...

$58 million effort to study potential new energy source

17 hours ago

A research team led by The University of Texas at Austin has been awarded approximately $58 million to analyze deposits of frozen methane under the Gulf of Mexico that hold enormous potential to increase ...

And now, the volcano forecast

18 hours ago

Scientists are using volcanic gases to understand how volcanoes work, and as the basis of a hazard-warning forecast system.

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.