Feeds

Scientists seek noctilucent cloud enlightenment

More night-shining expected in 2009, but why?

  • alert
  • submit to reddit

Boost IT visibility and business value

Scientists are suggesting 2009 may prove a bumper year for northern hemisphere noctilucent clouds - high-altitude pre-dawn and post-sunset features illuminated by the Sun from below the horizon.

According to New Scientist, skywatchers last week snapped the first examples of the clouds, although NASA's Aeronomy of Ice in the Mesosphere (AIM) spacecraft got the first indications back on 22 May.

Noctilucent clouds occur at around 80km up in the atmosphere. They were first spied hovering above polar regions in 1885, "suggesting they may have been caused by the eruption of Krakatoa two years before".

However, they have of late been creeping towards the equator, now appearing at latitudes as low as 40°.

Why this is happening is unclear. Some suggest "it could be due to an increase in greenhouse gases... because the gases actually cause Earth's upper atmosphere to cool, and the clouds need cold temperatures to form".

First satellite snaps of the noctilucent clouds. Image credit: NASABack in 2007, AIM principal investigator James Russell III of Hampton University suggested the increased frequency of Polar Mesospheric Clouds (PMCs, as they're known when viewed from space - see pic) might be due to "a connection with global changes in the lower atmosphere, and could be an early warning that our environment is being altered".

He said: "It is clear that PMCs are changing, a sign that a distant and rarified part of our atmosphere is being altered, and we do not understand how, why, or what it means."

New Scientist, though, notes that "their abundance also seems to rise and fall with the Sun's 11-year cycle of activity", elaborating: "The clouds thrive when the sun is quiet and spews less ultraviolet radiation, which can destroy water needed to form the clouds and can keep temperatures too high for ice particles to form."

The Sun has in recent years been relatively quiet, prompting AIM lead scientist Scott Bailey to predict around twice as may noctilucent clouds as when the Sun hits peak activity.

But no one's really sure what to expect. New Scientist adds that the clouds' activity "seems to peak roughly a year after solar activity hits its minimum, which researchers believe happened in December 2008".

Bailey, though, noted that "the exact time lag between solar minimum and peak cloud activity is uncertain, and researchers aren't entirely convinced a lag even exists". He concluded: "There's no explanation for it. Every model says the clouds should respond immediately to what the sun is doing."

Accordingly, those of you hoping to enjoy some noctilucent cloud action might get the best chance between mid-June and mid-August - or not, as the case may be. ®

Gartner critical capabilities for enterprise endpoint backup

More from The Register

next story
LOHAN packs bags for SPACEPORT AMERICA!
Spanish launch goes titsup, we're off to the US of A
Gigantic toothless 'DRAGONS' dominated Earth's early skies
Gummy pterosaurs outlived toothy competitors
'Leccy racer whacks petrols in Oz race
ELMOFO rakes in two wins in sanctioned race
TRANSMUTATION claims US LENR company
Ten points of stuff out of a five pound bag
Boffins ID freakish spine-smothered prehistoric critter: The CLAW gave it away
Bizarre-looking creature actually related to velvet worms
CRR-CRRRK, beep, beep: Mars space truck backs out of slippery sand trap
Curiosity finds new drilling target after course correction
BAT-GOBBLING urban SPIDER QUEENS swell to ENORMOUS SIZE
But they'd lose a deathmatch against the coming Humvee-sized, armoured Arctic ones
Astronomers scramble for obs on new comet
Amateur gets fifth confirmed discovery
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
7 Elements of Radically Simple OS Migration
Avoid the typical headaches of OS migration during your next project by learning about 7 elements of radically simple OS migration.
BYOD's dark side: Data protection
An endpoint data protection solution that adds value to the user and the organization so it can protect itself from data loss as well as leverage corporate data.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?