The lingering volcanic plume from the Hunga Tonga-Hunga Ha‘apai eruption has rekindled spectacular sunsets over Australia this week.
Recently retired ABC weather presenter Graham Creed saw the impressive skies from his farm in New South Wales.
"The key to it is the volcanic dust from the volcano in Tonga," he explained.
Yes, from the eruption over a month ago.
Since the initial explosion, the plume has been circling around the atmosphere, too high to affect our day-to-day weather, but adding a red glow to sunrises and sunsets.
"It's a bit like that bushfire smoke back in 2019 that was circulating around the globe," according to Mr Creed.
The plume has now roughly made its first full loop of the globe and has been travelling over Australia again this week.
"So that's why we've seen these really glowing skies at sunrise and sunset," Mr Creed said.
"The interesting thing is that at sunset you can actually see the meteorological sunset, which is when the clouds change colour but as the sun goes over and it starts to go dark that's when the volcanic ash was illuminated and was bending and refracting the light."
Volcanic eruption reached all the way up to the mesosphere
Recent analysis from NASA has found the initial eruption exploded up through the first two layers of the atmosphere — the troposphere and stratosphere — to briefly burst into the third layer of the atmosphere, the mesosphere.
They calculate the eruption rose to 58 kilometres at its highest point.
Despite this initial burst, the majority of the projectiles are now circling the stratosphere.
According to Natural Hazards Consulting's Andrew Tupper, former manager of the Darwin Volcanic Ash Advisory Centre, the plume has become harder to identify as it disperses.
But it is still possible to see the remnants of the Tonga Volcano on lidar imagery taken over eastern Australia earlier this week.
"[It's] showing us what is probably mostly sulphate aerosols (maybe a bit of volcanic ash) around 25 km in height in the stratosphere, sitting well above the troposphere where the clouds are," according to Dr Tupper.
This is backed up by haziness on recent satellite imagery.
"In a nutshell — yes — the cloud is in lots of places, including over Australia, and will be helping some very nice sunsets," Dr Tupper said.
A sight worth remembering
"It was really a spectacular thing to watch," Mr Creed said.
"The last time I've seen it was when Mount Pinatubo erupted in the Philippines."
That was all the way back in 1991.
