问答题
On May 18, 1980, Mount Saint Helens in Washington ejected into the atmosphere an estimated 540 million tons of ash.
【正确答案】540/5.44=99 So this was 99 times the annual man made PMio emissions.
【答案解析】
【正确答案】Mixed. Most of that huge amount of material fell within 50 miles of the site, covering a huge area up to a few feet thick. However it put enough fine material into the atmosphere that we had world wide reddened sunsets for almost a year.