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Noctilucent Clouds

It’s Noctilucent Cloud season here in the northern hemisphere. These rare clouds – the name means “night-shining” – only appear in the sky at specific times of night and times of year, and the next three months (mid-May till mid-August) are the best time for northern stargazers to spot them (southern stargazers get a chance between mid-November and mid-February).

These high thin clouds are seen in deep twilight, and as the name suggests they look lit up, as indeed they are. When the Sun is between 6 and 16° below the horizon, that is during nautical twilight and much of astronomical twilight, its light can still shine on these high clouds, floating 80km up in the atmosphere. Check out your twilight times and head outside on a clear night to try and spot them.

In addition to these restrictions in time only stargazers between 50° and 65°N can see them. That’s most all of the UK, so we’re ideally placed for hunting NLCs.

No one’s quite sure why they form, and indeed they weren’t seen (or at least weren’t reported) before 1885, and so there is some suggestion that they’re linked with man-made climate change. Whatever the case they are beautiful clouds to see, so take the chance over the next few months.

  1. astroslacker
    May 23, 2012 at 08:43

    Radio 4’s “So you want to be a scientist” programme had a listener who teamed up with Prof. Nick Mitchell of the University of Bath to study this phenomenon.

  2. Stewart Watt
    May 27, 2012 at 23:22

    Was at a talk by Ken Kenneady,director of the BAA aurora section, on NCL and they have been seen as low as 39 degrees in Portugal and several sightings in the low 40’s

  3. June 16, 2012 at 13:43

    noctolucent clouds 1st reported in the earths atmosphere in 1885 so is it a new phenomnon is it caused by man pumping co2 into earths lower reaches of the atmosphere as some say it is i dont think it s that because co2 acts like a blanket letting the suns heat in and not letting it back out ence the warming but these noctolucent clouds are way way high a bove the earths lower atmosphere where global warming is suposedly formed around the world there was a report i read that scientists found that carbon dioxide was mixing into the very high atmosphere and this is where c02 has a opposite effect it actually reflects the suns heat back into space and this is making the high atmosphere very cold temps of minus 90 were recorded last year this is new said the reports but something very strange is happening said one scientist may be the noctolucent clouds are co2 getting in the high atmosphere mixing then freezing at great hights and the particles when it by the sunlight turn electric blue high up in the earths atmosphere

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