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Professor Hal explains what happened during Beirut explosion
5 August 2020, 10:59
What is the white cloud shown in the Beirut explosion? Does it match the explanation of ammonia nitrate? Professor Hal Sosabowski told LBC what really happened.
Videos from Lebanon shocked the world as they circulated on social media. With smoke swirling high in the sky, small flashes can be seen near the ground before the huge explosion led to a large white mushroom cloud spreading quickly through the city.
The country's Prime Minister says yesterday's blast was caused by tonnes of unsecured ammonium nitrate catching fire in a warehouse.
So what exactly happened? Professor Hal, the Professor of Public Understanding of Science at the University of Brighton and Mystery Hour legend, spoke to Tom Swarbrick to explain what we saw.
He said: "This is society not learning from its own mistakes. For hundreds of years, there have been situations where too much ammonium nitrate has been kept in the same place at the same time.
"It's a powerful oxidant and in the presence of any sort of fire, it has the capacity to self-detonate, which is precisely what happened.
"If you have a certain amount of it, it can do things that it can't do in smaller amounts.
"We need to differentiate between a fire and a detonation. This started with a fire, with the red smoke. The red smoke is nitrogen dioxide, one of the key composition products. At some point, the ammonium nitrate itself decomposed and it produces lots and lots of nitrogen and oxygen. Gases expand and that's where you saw that terrible pressure went.
"It's very similar to the airbag in your car, which is sodium azide, a nitrogen-containing compound which goes from being a small solid to a huge amount of gas."
Regarding the white cloud we saw, Professor Hall said: "You saw this big white ball of condensation, similar to clouds you see above aircraft wings. It's essentially a supersonic detonation with a shockwave that goes faster than sound.
"On the footage, we saw the fire, we saw the explosion, we saw the ball and you could almost see the shockwave rushing towards the viewer."