Eyjafjallajökull Eruption and European Skies

April 22, 2010

20100422 – Thursday - Eyjafjallajökull Eruption and European Skies
Kosmas Gazeas
Summary Author: Kosmas Gazeas; Jim Foster

The photo sequence above shows views of the western horizon near Leiden and Noordwijk, The Netherlands just before and just after the arrival of a volcanic ash cloud. The appearance of high, striated clouds near sunrise or sunset, fiery twilight colors including a purplish cast to the twilight sky and an increase in the brightness of the aureole are evidence of volcanic ash overhead. Recent eruptions from the volcano buried beneath the Eyjafjallajökull Glacier in Iceland directed a huge plume of ash toward Europe. After breaching the stratosphere and sweeping across Ireland, the U.K. and the Scandinavian countries, this tenuous “cloud,” approximately seven miles (11 km) above the Earth’s surface, drifted over The Netherlands on April 16. In addition to the greater path length of sunlight when the Sun is near the horizon, the dramatic increase in the number of aerosols (ash, dust and sulfur dioxide) injected into the atmosphere following a major volcanic eruption leads to even greater scattering/reddening and enhanced coloration of the twilight sky. Since aircraft were grounded for five days in many European countries, there were few if any jet contrails to detract from the purity and color of the sky near the horizon.

The two photos on the left were taken from Leiden on April 15, 2010, before the ash cloud appeared. Note the halo phenomena. The two photos on the right were snapped at Noordwijk on April 16, 2010, the day the ash cloud first impacted the west coast of The Netherlands. Note the well defined aureole and multiple corona rings.

Photo details: Canon PowerShot SD870 camera; Focal Length of 28 mm (wide angle) and 105 mm (close-up) – 35 mm equivalent; Aperture of f/2.8; Exposure time of 1/125 sec; ISO 100.