DO \OLCAXIC EXPLOSIONS AFFECT OUR CLLMATE! 



VJ] 



BUT KRAKATOA DID NOT EJECT AS MUCH 

 ASHES AS KATMAI 



Although the violence and destructive- 

 ness of this celebrated eruption places it 

 in the first rank, and the quantity of 

 matter ejected was very great, yet when 

 we compare the depth of ashes falling at 

 considerable distances from the Island of 

 Krakatoa with the quantity of ashes 

 which fell on Kodiak Island after the 

 eruption of Mount Katmai it appears that 

 the volcano of Krakatoa was far inferior 

 in this respect to the recent one. 



According to the investigations of \'er- 

 beek, the average depth of the ashes at 

 the distance of lOO miles from the vol- 

 cano of Krakatoa was about one quarter 

 of an inch. We have seen that at Kodiak 

 Island the depth of the deposit from Kat- 

 mai was about one foot and the average 

 depth at a distance of lOO miles from 

 Katmai at least one inch (see page 132). 

 If, then, the air was filled with haze from 

 Krakatoa for two years after the erup- 

 tion, it need not surprise us that a great 

 amount of haze occurred following the 

 eruption of Katmai. 



But it must not be forgotten that the 

 violence of the eruption of Krakatoa was 

 most extraordinary. It is possible that 

 although the amount of ashes sent out 

 from Alount Katmai may have greatly 

 exceeded the quantity sent out from 

 Krakatoa, yet the height to which the 

 ashes were projected in the atmosphere 

 by Krakatoa may have greatly exceeded 

 the height to which they were projected 

 from Katmai. Thus perhaps we ought 

 not to infer that the meteorological con- 

 sequences of Katmai should last as long 

 as those extraordinary ones which were 

 observed after Krakatoa. Recent pyr- 

 heliometer measurements, however, show 

 that in January, 1913, the sky was still 

 abnormally hazy. 



It is only since just before the Kraka- 

 toa eruption that we have had measure- 

 ments of the intensity of solar radiation 

 comparable to those which were available 

 in 1912. From a paper of Prof. H. H. 

 Kimball* I copy the accompanying illus- 

 tration, which shows the fluctuation of 

 the annual solar radiation received at the 

 earth's surface as measured at different 

 stations, f 



VIOLEXT VOLCANIC OUTBURSTS SERIOUSLV 



DIMINISH THE AMOUNT OE HEAT WE 



RECEIVE FROM THE SUN. 



It is apparent that very great de- 

 partures from the usual intensities oc- 

 curred from 1883 to 1887, 1888 to 1893, 

 and from 1902 to 1904 respectively. 

 Having now convinced ourselves that 

 such departures may reasonably be ex- 

 pected in consequence of great volcanic 

 eruptions, it is interesting to find, if we 

 can, the causes of the diminished solar 

 radiation at about 1891 and 1903 re- 

 spectively. 



The activity of the Island of \'ulcano 

 lasted 20 months — from August 3. 1888. 

 to March 22, 1890. The most violent 

 explosions occurred on August 4, 1888; 

 December 26, 1889. and March 15, 1890. 

 An eruption which took place there on 

 January 6, 1889. was observed by A. 

 Ricco from the Observatory of Palermo 

 to be sending a column of smoke to the 

 height of more than 6 miles. 



An eruption of Mayon, in the Philip- 

 pine Islands, took place December 15. 



1888. \'ast columns of ashes ascended 

 from the crater, and in a short time the 

 darkness was so intense that, though it 

 was midday, lights had to be used in 

 Manila. Violent eruptions were also re- 

 ported in the same year in other islands 

 of the Philippine group. 



A vessel passing the Island of Oshima. 

 in Japan, reported violent eruptions of 

 the volcano of Miharaizan on April 13, 



1889. O" January 16. 1890, a violent 

 eruption took jilace at Mount Zoo, near 

 the town of Fukuyama, in Japan. 



In February, 1890, there was the vol- 

 canic eruption at the Island of Bogoslof, 

 in Bering Sea. Three small new islands 

 were created in the immediate vicinity 

 and the island was raised i.ooo feet. 

 Ashes were collected in Unalaska. about 

 40 miles distant. 



1!ANDAI-SAN THROWS UP JOG 

 TONS OE MATERIAL 



MILLION 



On June 7, 1892. a severe erupt 



ion 



* Bulletin of the Mount Weather Observa- 

 tory, vol. 3, Part IT. 



t Professor Kimball's data comprise the four 



broken lines near curve A of the figure, page 

 i()6. I have marked them i-i (from 1883 to 

 1900); 2-2 (from iS<y3 to 1903); 3-3 (from 

 1901 to 1905): 4-4 (from 1906 to 1909). The 

 results of different observers have been com- 

 bined and smoothed, as will be stated below. 

 Results of this kind from single stations are 

 much influenced by local haziness. In future 

 years much fuller information will be available. 



