The Volcanic Science Of Ash
Ash Cloud Formation And Dispersion
Volcanic eruptions are fascinating geological phenomena, but they don’t usually break into the news cycle unless they are spectacular, come with a risk of tsunami, or create an ash cloud that might reach UK airspace.
Though not life-threatening, the recent volcanic eruption near Grindavik, Iceland, in August generated an ash cloud that drifted over the British Isles later that month, receiving extensive media coverage.
Pressure And Particles
But why would a volcanic eruption nearly 900 miles away impact UK airspace? To answer this, we need to understand the science behind volcanic ash cloud formation and dispersion. The magma, or molten rock, that volcanically erupts through the Earth’s crust contains pressurised gases such as sulpher dioxide. Most of this erupting magma spews out as flowing lava on the surface. However, the explosive eruption shreds some of the lava into tiny particles, and the escaping gases launch this material into the air, where it cools down and solidifies into a volcanic ash cloud.
The dispersion patterns of this ash cloud depend on particle size, wind speed and direction, and the type of eruption. The largest particles (around 2mm, about the diameter of a grain of rice) fall closest to the volcano, creating an almost unbreathable atmosphere. The smallest particles are carried by the wind, traveling in whichever direction and at whatever speed the wind moves, and are transported the furthest.
Carried On The Breeze
It is this type of volcanic ash cloud that has been carried south to the UK from Iceland by the prevailing winds. If the eruption is especially large, these volcanic ash particles can be launched into the upper echelons of the atmosphere, where they combine with other dust particles as condensation nuclei. Water vapor condenses around these particles to create clouds, which are then incorporated into the broader atmospheric cloud dispersal process.
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I am a practising HR consultant working with several start-ups on an ongoing and ad-hoc basis in the London and M4 area, and am a Chartered Member of the Chartered Institute of Personnel and Development or CIPD. I am the Director of thecareercafe.co.uk; thecareercafe.co.uk is a resource for start-ups and small business. It includes a blog containing career advice, small business advice articles, HR software reviews, and contains great resources such as HR Productivity Apps.
