Volcanic eruption on the Tonga Islands colored the sky

After the Tonga Islands volcano erupted in January 2022, particles from the eruption spread into the air. This high amount of aerosols in the air is the origin of the color of the ocean sky.

On January 15, the undersea volcano in the Tonga archipelago erupted. Then it destroyed almost 90% of the surface of a fortunately uninhabited island east of Australia. This explosion released many particles that reached the second layer of Earth’s atmosphere: the stratosphere.

From the Tonga Islands to all over the world

The peculiarity of this eruption is the fact that the Volcanic smoke and sulfur dioxide released from the volcano have already traveled the world. In fact, after converging en masse in New Zealand, these broadcasts ended up in orbit around the planet. This is therefore the second time that Remains of the Tonga volcano can be found in the sea sky. Since April it is possible to see a very colorful sunrise at dawn in New Zealand and Australia.

Underwater volcanic eruption in Tonga Islands seen from space. Credits: MAXPPP – TONGA METEOROLOGICAL SERVICES HA

A natural phenomenon: afterglow

This is called the afterglow, because there is a persistence of a state after its cause has disappeared. However, these are the Aerosols in the stratosphere, which are the origin of the color pigmented from the sky. Basically, it is the particles in the atmosphere that scatter the sunlight. This gives the color of the sky. However, when the sulfur dioxide released by the volcano turns into an aerosol in the second layer of Earth’s atmosphere, it will change the intensity of the light scattering. In fact, the aerosols will then impede the passage of light between the particles. The latter continue to scatter the sun’s light, but in a curved fashion that leaves room for light Shades of blue, purple or red.

This new passage of light, modified due to the aerosols present in the stratosphere, therefore explains this strong intensity of red color present in the oceanic sky. This phenomenon is much more visible at dawn or at sunset. The colors then reach their highest intensity. The clouds also play a role in this colored sky by reflecting the colors given by this phenomenon.

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