Feeds

Scientists seek noctilucent cloud enlightenment

More night-shining expected in 2009, but why?

  • alert
  • submit to reddit

Intelligent flash storage arrays

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. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
Bond villains lament as Wicked Lasers withdraw death ray
Want to arm that shark? Better get in there quick
Renewable energy 'simply WON'T WORK': Top Google engineers
Windmills, solar, tidal - all a 'false hope', say Stanford PhDs
The next big thing in medical science: POO TRANSPLANTS
Your brother's gonna die, kid, unless we can give him your, well ...
SEX BEAST SEALS may be egging each other on to ATTACK PENGUINS
Boffin: 'I think the behaviour is increasing in frequency'
NASA launches new climate model at SC14
75 days of supercomputing later ...
Britain's HUMAN DNA-strewing Moon mission rakes in £200k
3 days, and Kickstarter moves lander 37% nearer takeoff
Reuse the Force, Luke: SpaceX's Elon Musk reveals X-WING designs
And a floating carrier for recyclable rockets
Simon's says quantum computing will work
Boffins blast algorithm with half a dozen qubits
prev story

Whitepapers

Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
How to determine if cloud backup is right for your servers
Two key factors, technical feasibility and TCO economics, that backup and IT operations managers should consider when assessing cloud backup.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Getting ahead of the compliance curve
Learn about new services that make it easy to discover and manage certificates across the enterprise and how to get ahead of the compliance curve.