Shock from a volcanic eruption near Tonga reaches the Netherlands | Science

A unique measurement, that’s what meteorologist Wouter van Bernebeek calls an observation. “This pressure wave has already traveled over 17,000 kilometers!” Fellow meteorologist Wilfried Jansen van Weather Plaza: , what a nice sight to see this like that! Wethermann Michel Severin also calls it “Very Special!” “The amplitude at the end was 3 hPa, much higher than expected!” “It shows just how powerful that bang was this morning…” says Van Bernebeck.

The shock wave passed over the Netherlands between 8 pm and 9 pm. Severin: , anyone with a barometer can see air pressure rise sharply when a wave approaches and drop rapidly after passing. Accurate air pressure gauges recorded a difference of at least 3 hPa from top to bottom. It took nearly an hour for the air pressure to return to normal.”

We did not feel the so-called pressure wave, and we hardly notice it. “We are all familiar with air pressure waves. The heavy fireworks that went off during the New Year and the days before it caused loud explosions in many villages and towns. Explosions that sometimes shook windows. This same phenomenon was now happening all over the world. The volcano erupted with great force pushing the air above the volcano away. This created an air movement that caused a strong air pressure wave to move away from the volcano in an ever-widening circle.”

The air pressure is now back to its previous level. “The powerful eruption creates a large-scale air pressure wave that moves around the world very quickly. The volcano is located almost literally on the other side of the world, more than 16,000 km away. However, the air pressure wave loses so little energy along the way, that it can also be measured Pressure wave over our country, ”explains Severin.

Severe volcanic eruptions can lower the average global temperature within a relatively short period of time. Meteorologists don’t expect this right away. Van Bernebeek: “Because some extreme weather phenomena (such as thunderstorms) sometimes cause sharp fluctuations in air pressure. It is of course characteristic that such a shock wave (which runs in a few seconds) easily travels such a huge distance.”

The eruption of the Honga Tonga Hapai volcano can be seen from space. A Japanese weather service satellite was able to record it in detail. In a short time the formation of a huge ash cloud could be seen, but what was even more impressive was the shock wave that became visible for thousands of kilometers around the ash cloud.

Since the volcano released a huge amount of ash and debris into the atmosphere in a very short time, the air around the volcano was pushed away with great force. This triggered a shock wave that reached thousands of kilometers from the volcano. “The great force with which this phenomenon occurred created a wave in the atmosphere that spread like a ripple in the water around the volcanic eruption,” Jansen tries to explain the phenomenon.

Measurements also showed a temporary rise in air pressure in New Zealand. Jansen: , That’s because the air is compressed along the edge of the shock wave, so that more air is temporarily available. At that moment the air pressure rises for a short time. Several weather stations in New Zealand showed the air pressure rising from 2 to 3 hectopascals in 10 to 20 minutes, after which the air pressure decreased and then stabilized again.”

He continues: “These types of air pressure increases are not unique to meteorology, but the current situation makes them very special, especially given the distance between the volcano and New Zealand, which is more than 2,000 kilometers!”