Volcanic ash falls on Oxford
Oxfordshire residents may have noticed a thin film of grime that coated cars and windows overnight on Thursday April 15th, and the haziness of the skies over the weekend. Both effects are due to the volcanic ash being emitted from the Icelandic volcano, Eyjafjallajökull.
Microscopic examination of the ash that has settled to the ground shows that it is made up of blocky grains of frozen volcanic glass and mineral grains (microscope images: grains are about 50 microns across). These particles are larger than most pollen grains, and are unlikely to cause noticeable effects to anyone who is not sensitive to mineral dust. The ash particles which remain in the atmosphere are likely to be smaller (which is why they haven't yet fallen out). Scientists from Oxford are engaged in tracking and measuring both the atmospheric ash cloud, and the deposits from the ground.
High power microscope image of 2 grains of volcanic ash from Eyjafjallajökull eruption. Each grain is about 50 microns (2 hair widths) across. Image taken at the Diamond Light Source by David Pyle.