Volcanic cloud grabs the headlines...
You've probably awoken today to hear the news of a volcanic eruption in the Eyjafjallajoekull area of southern Iceland - the .
The volcano erupted beneath a glacier and was still actively spewing-out vast quantities of ash by midnight last night (Wednesday). Spectacular stuff indeed.
The impact here across the British Isles has become profoundly apparent this morning, as the ash cloud - up at between 20,000 to 35,000ft - potentially threatens the safety of airliners.
I was very interested listening to retired airline pilot chatting to Steve LeFevre on 91Èȱ¬ Radio Bristol's Breakfast Show this morning.
Eric was flying a British Airways Boeing 747, Flight 009,Ìýat night near Java in June 1982, when - at a cruising altitude of 36,000ftÌý-Ìýhis aircraft unexpectedly penetrated a vast cloud of volcanic ash thrown-up by the erupting Mount Galunggung. Ingestion of the highly abrasive ash resulted in the sequential failure of all four engines.
when the crew's persistence eventually paid-off,Ìýmanaging to re-lightÌýthe damaged engines after a powerless descent seemingly towards inevitableÌýditching in the dark Indian Ocean. Their close escape emphasisedÌýthe dangers posed by such volcanic clouds to aircraft and so believe me, if your flight has been cancelled today, it's beenÌýfor very sound reasons!
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The wider weather situation todayÌýis not great news for flights in and out of the country, as the ash cloud is expected to spread further southwards with each advancing hour, including across many parts of Britain.
We've got an area of high pressure located to the NW of Ireland, around which the clockwise circulation - including the winds high aloft - will tend to guide the ash cloud closer to us, dispersing slowlyÌýas it does so.
Down here at ground level in the West Country, any meaningful effects will be essentially nil. You're very unlikely to see visible dust, such asÌýbrought to us occasionally on warm plumesÌýfrom the Sahara, as I explained in a blog from last year.
However, one potential outcome could become apparent during our sunsets and sunrises over the next couple of days.
The ash cloud, spread in aerosol form high aloft, can often result in very vivid colours atÌýdawn and sundown. Bright reds, oranges, violets and pinks can adorn the sky in such situations, as exemplified by many contemporary reports from across the British Isles after the devastatingÌý.
Obviously,Ìýthis time it'sÌýa phenomenon on nowhere near the same pan-global scale (and the Krakatoa event resulted in worldwide temperatures falling by up to 1.2C the following year). Nonetheless, it's certainly worth watching for any changes in our skies towards sunset and indeed through tomorrow and into the weekend, too. If you spot anything by way of ultra-colourful sunsetsÌýor sunrises,Ìýdo send the photos through to us and I'll put them on the blog - you'll find instructions for sending these here.
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I'm Ian Fergusson, a 91Èȱ¬ Weather Presenter based in the West Country. From benign anticyclones to raging supercell storms, my blog discusses all manner of weather-related issues. I also provide updated race weekend forecasts tied to our 91Èȱ¬ coverage of Formula One. You can follow me on , too.
Comment number 1.
At 15th Apr 2010, barry white wrote:I am confused to what happens to the dust after it passes the UK.
Does it just fall to earth? Or create rain?
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Comment number 2.
At 15th Apr 2010, Ian Fergusson 91Èȱ¬ Weather wrote:Hi Barry, on this occasion, it'll probably do a combination of both, to varying degrees - albeit any rain is unlikely to fall across the UK itself in any meaningful amounts, as we're locked into a fairly prolonged spell of dry weather influenced by high pressure to the NW. The ash - becoming increasingly diffuse - will journey across vast distances (e.g., much of continental Europe) by the prevailing winds aloft; much of it ultimately settling into the Atlantic Ocean beneath the dominant anticyclonic cell centred NW of Ireland but some across dry land, too (albeit so finely dispersed across most of the UK to be effectively invisible to the naked eye). This process could take quite a number of days. Elsewhere, the ash particles can become widely entrained into weather systems and clouds where they act as the hygroscopic or condensation (= water attracting) nuclei around which precipitation will eventually form and fall, or are otherwise flushed-out of the atmosphere in rain and snow. Best, Ian
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