Understand how the volcanic eruption in Chile made the Brazilian sky purple

On April 22, the Calbuco volcano, located in Los Lagos, Chile, erupted for the first time after 40 years. The massive cloud of volcanic dust was launched at a height of 10 km, turning the surroundings into a gray ash-covered desert.

This eruption has caused the cancellation of dozens of flights and other problems in all countries around Chile, especially Argentina, Uruguay and Brazil. The exact moment of the explosion was recorded in an impressive video by Walter Witt, who walked a trail around Calbuco.

And what do we here in Brazil, besides missing some flights to Chile and Argentina, have to do with this event? “We won as a gift” a beautiful purplish twilight that was photographed in Rio de Janeiro by Hélio de Carvalho Vital on April 26th. His photos record a sunset that, instead of reddish or orange, showed colors like lilac, violet and purple.

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Understand how the volcanic eruption in Chile made the Brazilian sky purple

Natural disasters

Taking into account the interference caused by the eruption of the volcano in the atmosphere of all nearby and not so close regions, it is possible to explain what might have happened to make the sky look different in color. When a volcano erupts, it explodes with the pressure accumulated underground.

The crater is the weakest point this pressure finds to escape. When this happens, tons of volcanic dust, which is mainly composed of sulfur dioxide, are thrown upwards. Wind and air masses moving across the continent carry this sulfur dioxide over huge distances in the form of a fine mist that contains tiny particles of this substance and is suspended in the air.

Calbuco's volcanic dust spreads over Chile.

In order to understand the purple coloration, we must first understand how the “ordinary” colors of the sky form: the blue during the day and the reddish and orange colors when the sun is rising or setting. What happens is that the rays of sunlight penetrate the atmosphere and are reflected by the particles of various materials that compose it.

Adding this to the light's penetration angle and the distance it travels to reach our eyes, we have the colors we know. Blue happens during the day, when the rays penetrate the atmosphere at a right angle and travel a shorter distance to us. When the sun is low, the angle and the greater distance to reach our vision causes the sky to color more red.

The purple color

We finally reached purple. This color probably dominates the sky because sunlight rays also interact with this sulfur dioxide mist scattered from the volcanic eruption, as well as the materials already present in the air. The red of the sunset gets stronger with the presence of dioxide, while part of the mist suspended in higher places reflects the blue color. This mixture, as we learned one day in primary school, forms the color purple.

Other colors can also be formed in the sky through this same effect, generating exotic and very beautiful colors. In addition to filling our eyes, these pitch changes also have a very interesting function: scientists can infer amounts of volcanic dust emitted by certain eruptions through historical paintings showing different colors in the sky.

The biggest of all eruptions

A classic example is the painting “The Scream” by Norwegian painter Edvard Munch. In it, we can see strong reddish colors in the sky, probably caused by the effects of one of the largest volcanic eruptions in history, that of the Krakatoa volcano, located between the islands of Java and Sumatra, in Indonesia, about 11 thousand kilometers from where The painting was painted to give an idea of ​​the extent of this natural catastrophe.

"The Scream" by Edvard Munch.

This outbreak, which occurred in August 1883, affected planet Earth as a whole and was heard five hours later on the east coast of Africa. This was considered the loudest sound ever produced on the planet. Tsunamis have affected boats off the coast of South Africa, and even the English Channel between England and France has changed its tides.

Part of the material expelled in the explosion was thrown out of the atmosphere, with amounts of volcanic dust orbiting the Earth. The following year, 1884, the planet's average temperature dropped by 1.2 ° C and the combination of the massive amount of sulfur expelled with atmospheric water generated acid rain in many places.

Lithograph of 1888 depicting the eruption of Krakatoa.

Spreading the world

No wonder it has been possible to witness changes of all kinds, including the color of the sky during twilight, in various parts of the world. By comparison, the Calbuco volcano eruption does not reach Krakatoa's feet, but it will still cause a series of negative climate changes, such as the deaths of thousands of salmon, of which Chile is one of the world's largest producers.

The imposing Calbuco.

The cloud of volcanic dust, if it keeps its course, is soon to reach the African continent and soon after the Middle East. It is very likely that it will also be possible to witness in these places the different colors that have painted the Brazilian sky. It remains to be hoped that the negative effects of this angry volcano will be as minor as possible.