Image credit: NASA GSFC/JPL
It’s pretty hard to avoid hearing about the volcanic ash plume grounding flights all over Europe, caused by the eruption of Eyjafjallajökull in Iceland. It occurred to us here at GeekDad that many kids, and probably many adults, had some questions about the ash plume, why it was having the effect it is, and what we could expect its effects to be in the future. Here, then, are six likely questions about the volcanic ash cloud/plume, and their answers. Just don’t ask us to pronounce “Eyjafjallajökul.”
1. What is the ash cloud made out of, anyway? - Volcanic ash is mostly made up of tiny bits of rock, so small and light that they are easily carried through the air. The most recent eruption of Eyjafjallajökull occurred beneath glacial ice (which is, not surprisingly, fairly common in Iceland). The eruption melted much of the glacier, as you’d expect, but the cold caused the lava to cool very quickly and form minuscule particles of glass which got carried into the ash plume.
2. Planes can fly through regular clouds, so why can’t they fly through the ash? – All volcanic ash plumes can clog up airplanes’ sensors and coat the plane, thus adding to its weight and altering its delicate balance. This plume is particularly dangerous because of its glass particles, which can melt in the enormous heat of the plane’s engines and damage and/or jam the machinery. Jet airplanes flying through ash clouds have been known to have all four engines cut out, and propeller aircraft aren’t likely to fair much better.
3. All these particles are heavier than air, right? So why don’t they fall to the ground? – Well, you’ve no doubt seen smoke rise from a chimney or grill — the visible parts of that smoke are mostly soot and ash, yet they obviously float. The reason is, essentially, the difference between weight and density: the particles are simply widely spaced enough that the air is actually denser. We can be thankful that a whole lot of the volcanic ash produced by eruptions is in fact too dense to float, and will fall to the ground after it completes the trip the eruption’s force sent it on. By “we” here I mean anyone not too near the volcano, because those who are tend to get a lot of ash on them. Some of the volcanic ash plume will fall eventually, due to random clumping creating bits denser than air, but ash plumes can literally stay in the atmosphere for years. The ash plume has an advantage over smoke, too, in that the ash is typically released at a much higher altitude.
4. Other than halting air travel, what other effects can ash clouds have? – The most significant effect is typically to weather. It’s not yet clear whether the eruption of Eyjafjallajökull will affect global weather, but major eruptions in the past certainly have. In 1783, for example, a volcanic fissure in Iceland called “Laki” violently erupted. The sulfur dioxide gases carried with its plume caused increased death rates all over Europe over the next month or two, but that was nothing compared to the meteorological effects. The winter of 1784 was one of the worst on record in both Europe and North America — the Mississippi River even froze at New Orleans! Laki, along with another Icelandic eruption shortly thereafter, had severe effects on crops in France over the next several years, which may have been a contributing factor in the French Revolution of 1789. And if you think that was bad, you should know it wasn’t nearly as significant as the 1815 eruption of Mount Tambora in Indonesia, which caused the Northern Hemisphere to experience “The Year Without a Summer” in 1816. Frost was reported in Connecticut in June, famine was widespread in the U.S. and Europe, and — less importantly, but interestingly — the lousy summer caused Mary Shelley and John Polidori (and their friends) to stay indoors while on vacation, resulting in the novel Frankenstein and the short story The Vampyre.
5. How long is this going to last? – It’s hard to say. The eruption is still going as of this writing, and predicting the length of volcanic eruptions is not an exact science, to say the least. It looks like the plume isn’t going to go away any time soon, and its effects on global weather will be largely determined by just how long the eruption keeps this up.
6. So, what can we do about it? – Well, unfortunately, the answer is: not a heck of a lot. We can be glad for our advanced technology that at least allows us to track the plume easily and will assist us in gauging its meteorological effects, if any. In the 1780s and 1810s, nobody had the slightest idea what was causing the extreme weather conditions. If you recall the eruption of Mount Pinatubo in the Philippines 19 years ago, you may remember red sunsets and some slight global cooling following it. Fortunately, its effects weren’t too severe outside of the Philippines; hopefully the eruption of Eyjafjallajökull will turn out no worse than that, but only time will tell.
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