1 In some months, the Ides is on the 15th, and in others, it is the 13th. 2  It's supposed to be on the day of the full moon. [See Roman Calendar.]. 3  March's Ides marked the beginning of the consular year: The two annually-elected Roman consuls took office on the Ides from c. 220 B.C. to 153.
In the case of Mount Pinatubo, the result was a measurable cooling of the Earthâs surface for a period of almost two years. Because they scatter and absorb incoming sunlight, aerosol particles exert a cooling effect on the Earthâs surface.The Pinatubo eruption increased aerosol optical depth in the stratosphere by a factor of 10 to 100 times normal levels measured prior to the eruption.ecause they scatter and absorb incoming sunlight, aerosol particles exert a cooling effect on the Earthâs surface. The Pinatubo eruption increased aerosol optical depth in the stratosphere by a factor of 10 to 100 times normal levels measured prior to the eruption.
The 1991 eruption of Pinatubo volcano in the Philippines created a new caldera with an average diameter of 2.5 km. Caldera collapse, which lowered the height of the volcano about 300 m, occurred following the ejection of nearly 10 cu km of tephra in one of the world's largest eruptions of the 20th century.he climactic eruptions on June 15, 1991, created a 2.5-km-wide caldera at the summit of Pinatubo volcano. The elevation of the caldera floor is more than 900 m below that of the pre-eruption summit of Pinatubo. Steam rises from fumaroles on the caldera floor in this October 4, 1991, view from the north.