© JoNovaHunga Tonga-Hunga Ha’apai.
On January 15th, Hunga Tonga launched a magma-powered thunderstorm that sent atmospheric shockwaves around the world. Ash, salt and particulates were carried through rising columns, right through the stratosphere, into the mesosphere and all the way up to 58 kilometers above Earth. For hours 400,000-odd lighting bolts zapped the airborne chemical soup.
The dust from Hunga-Tonga travelled West and reached Australia on Jan 18 - 20th. On Jan 21-22 flooding rain washed out the main railway line and roads in central Australia. Over the next few weeks, rains soaked the ground across parts of Queensland and New South Wales. By February 15th, the remnant volcanic dust that had circled the Earth and was back again creating rich red sunsets over Australia. A week or so after that, the rain bombs fell on South East Queensland, and travelled south through New South Wales to Sydney.
The big unknown is that the Hunga-Tonga volcano launched water vapor, salt and dust incredibly high — almost too high. The aerosols are far above the troposphere where rainfall originates and some of that floating ash was still too high even as it returned on the second lap of the Earth at 25km above sea level. On the other hand, some particles will fall out faster than others, others will be highly charged and possibly novel entities created in the monster lightning storm above the volcano, and some ash and particles will have been released at lower heights.
This post was inspired by Jennifer Marohasy who pointed out the weak La Nina conditions don't really explain the floods in Australia this year. She wondered if the
recent Australian rain was fueled by aerosols from Hunga Tonga and describes how rainfall has been linked to past eruptions in scientific papers: after
"El Chichon spewed 20 million tonnes of aerosols into the stratosphere in 1982, Hong Kong recorded very high rainfalls as the dust arrived across the Pacific".
