Three days later, another B29 and a weather observation plane left the Trinian air base early in the morning and exploded the second A-bomb over the city of Nagasaki at 1102 hours.[97]

The first bomb found its epicentre about one kilometre south of a weather front where a northern airmass and a southern airmass met. A tornado developed near the front. 'Thunder rumbled, black rain fell, and the sea breeze was strengthened and prolonged. In fact, the muddy rain contained the fallout.'[98]

At Nagasaki the mushroom-shaped cloud extended from 1,200 to 5,000 metres—base and top respectively. Immediately following the bombing, three radiosondes were released from the weather plane at an altitude of 4,000 to 5,000 metres. These were carried away to the east. From the data obtained, the wind velocity in the disturbance itself was estimated to have been about three metres per second, east or north-east. 'Rain was frequently admixed with ashes (black rain).'[99]

Incidentally, rumour had it that amongst the places not demolished by the bomb in Hiroshima were the brewery and the meteorological office!

On the tropical evening of 7 August 1945, I was relaxing off-duty with a group of fellow-officers in the mess at Milne Bay listening to the radio. I heard the broadcaster announce in a news flash that a US Superfortress had dropped an atomic bomb on Hiroshima, a large city in Japan. He spoke of incredible damage that had resulted from the blast, and as he talked on, a feeling came over me that the world had stopped for a moment, and that somehow it would never be the same again. The bluish-white glare that enveloped the stricken Japanese cities of Hiroshima and Nagasaki was like a ghastly curtain rung down suddenly on the world we had known. We looked at one another not clearly comprehending what had happened. What was an atomic bomb?

Bureau of Meteorology