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Theory links 'scarlet rain' to Mayon volcano

By M. Dinesh Varma

THIRUVANANTHAPURAM, AUG. 31. A new theory suggests that the multi-coloured rain received in some parts of the State recently could have its roots in the Mayon volcano eruption in the Philippines.

A senior scientific assistant in the Meteorological Department here has offered a plausible conjecture about the eruption of the Mayon Volcano in the Albay Province on July 26 and July 27 being the source of the unusual phenomenon in the State. In a report submitted to the Director General, Indian Meteorological Department, New Delhi, Mr. K.K. Sasidharan Pillai posits that the multi-coloured rain was the fallout of the fountaining of incandescent lava along with acid and gaseous emissions from the Mayon Volcano.

The report cites the "Smithsonian Institution's Preliminary Notices of Volcanic Activity" to point out that the emitted particles and gases, which were spewed onto the upper troposphere, could have been transported to Central Kerala by the tropical Easterly Jet Streams and accumulated by Cumulonimbus clouds, which eventually precipitated the multi-coloured rain.

The unusual red-coloured rain was first reported from Changanassery on July 26, followed by unusual rain and thunder in parts of Kottayam. Later, there were reports of `yellow smoke', `acid rain', `sulphurous odour', `scarlet rain', `blue-coloured water' and "abrupt rise in temperature of water on paddy fields', according to reports.

All these were centred on a pocket, with a spatial separation of a few metres (or 20 to 30 houses). Besides, the percentage distribution of the observed colours (red scoring a high of 55 per cent, yellow 20 per cent and green 10 per cent) more or less tallies with the natural percentage distribution of colouring compounds available on earth, the report says.

It says that the chain of occurrences more or less tallies with the meteorological characteristics of the Cumulonimbus (Cb) cloud, which is capable of transporting huge quantities of volcanic elements. The Cb cloud, which has a cellular structure and a base diameter of a few kilometres, can expand to a maximum height of 18 km jutting onto the tropopause level over the equator.

(In fact, information accessed from the website of the U.S. Government's "Volcano Hazards Program" states that once airborne, the prevailing winds may blow the eruption cloud hundreds to thousands of kilometres" from a volcano site).

The author disproves linkage of the coloured-rain to the recent eruptions of Mt. Etna in Sicily, because the geographical position of Etna is approximately 38 Degrees North Latitude and 15 Degrees East Longitude. The global wind circulation patterns in the upper and lower troposphere and the sheer geographic distance between the two places make it impossible for the Etna emissions to reach Kerala in such huge quantities.

In contrast, the Mayon volcano, has a geographic position 13 degrees North latitude and 123 degrees East Longitude, a height of 2,421 metres and a circumference of 130 km, putting it on a tangent to be ferried to Kerala by the Easterly winds.

The Easterly Jet Stream operates in the tropopause (18 km above sea level). Significantly, this stream, with a width of hundreds of kilometres, originates over the Philippines and passes over the South China Sea, Thailand, Bay of Bengal, Tamil Nadu, Kerala and the Arabian Sea before terminating over the East coast of Africa.

During July-August, the jet stream speed has been observed at 70 nautical miles (140 kph) at 10.6 km above sea level, with a peak momentum of 100 nautical miles at other levels. In his approximate surmise, the volcanic particles that were caught in draughts operating in the upper reaches of the tropopause could take around 25 hours to reach Kerala. It could take around 36 hours if the particles are being transported at lesser wind speeds.

The author goes on to explain the acid rain showers as stemming from transformation of sulphur dioxide emissions from the volcano dissolving with the water in the Cb cloud to produce sulphurous acid. And, given the fact that sunlight is available, the sulphurous acid is again transformed into sulphur trioxide by photochecmial reaction, which in turn, changes to sulphuric acid.

The author eliminates various theories which did the rounds about possible alternative causes such as meteorites (which travel at such high velocity that they are likely to burn out hundreds of kilometres above sea level), industrial pollutants (as neither are they available in such huge quantities nor do they possess such a spectacular colour spectrum), or a tornado with Saharan origin.

Mr. Sasidharan Pillai says that he had undertaken the study as a voluntary measure and to provide a plausible explanation that would put at rest the various speculations associated with the phenomenon.

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