On 5th September 1883 the people of Hawaii were amazed to see their sun turned green with rings of pink, red, orange-rose and brown. This phenomenon was observed and accurately recorded at the time by Sereno Bishop of Honolulu and is now known as Bishop’s Ring.
Ten days earlier and more than a thousand miles away a small island in the Sunda Strait between Java and Sumatra blew itself apart with the loudest bang on earth. The blast was heard across 4500 kilometres, and even in London instruments registered the concussion and continued to do so up to nine days later, when the echoes of the report were making their seventh circuit of the world!
A sea wave 100 metres high swept aside lighthouses like matchsticks, left a Dutch warship three kilometres up a Sumatran valley and drowning over 36,000 people
This was Krakatau. The explosion pushed a gigantic column of smoke and dust through the ceiling of the troposphere up to a height of 50 kilometres.
Something that made Krakatoa different from other major events in the 19th century was the introduction of the transoceanic telegraph cables. The news of Lincoln’s assassination less than 20 years earlier had taken nearly two weeks to reach Europe, as it had to be carried by ship. But when Krakatoa erupted, a telegraph station at Batavia (present day Jakarta, Indonesia) was able to send the news to Singapore. Dispatches were relayed quickly and literally within hour’s newspaper readers in London, Paris, Boston, and New York were being informed of the colossal events in the distant Sunda Straits.
Climatologists started to study the effect of volcanic dust in the atmosphere using Krakatoa as the baseline and today we have the International Airways Volcano Watch (IAVW) system for the safety of air transport following volcano eruptions.
Since volcanic ash is composed of very abrasive silica materials, it can damage the airframe and flight surfaces, clog different systems, abrade cockpit windows and flame-out jet engines constituting a serious safety hazard. Volcanic ash can also have a serious effect on aerodromes located downwind of a volcanic ash plume since it contaminates runways, ground equipment and aircraft parked or taxiing around the aerodrome.
The IAVW system is designed to detect and track the movement of volcanic ash in the atmosphere and to warn aircraft in flight about this hazard. There are nine Volcanic Ash Advisory Centres responsible for the provision of information related to areas affected by volcanic ash and its future movement. The centres are located at Anchorage, Buenos Aires, Darwin, London, Montreal, Tokyo, Toulouse, Washington and Wellington.
Deep underground, Vulcan, the blacksmith to the gods, keeps his forge going constantly building up enough heat and pressure in readiness for the time to ‘blow its top’ and throw debris and dust into the atmosphere