Sunday , November 29 2020

Giant dust is spread all over the world, talking about the laws of physics



Giant dust particles spread throughout the globe, and the responsible physical forces are still in the air, hidden somewhere in the wind.

Whatever it is, this mysterious influence is so strong that it can transport particles 50 times bigger than we ever thought it was possible to carry these big pieces all the way from the dry Sahara desert to the tropical Caribbean.

It is a performance that ought to believe the laws of physics, which rarely is a good sign. That means we've got something wrong along the way, and in our ignorance we can have overlooked an important driving force for climate change.

For nearly 30 years, scientists have known that small dust particles that have sprung up in the Sahara often drive on global wind to the Caribbean, 3,500 kilometers (2,000 kilometers) away from home.

Originally, this foreign cloud of desert dust was thought to contain particles no greater than 0.01 to 0.02 millimeters in diameter.

But recently, when scientists began collecting dust samples from floating buoys and underwater traps in the Atlantic Ocean, the large sizes of the particles hesitated their expectations.

Between 2013 and 2016, the Royal Netherlands Institute for Marine Research (NIOZ) found some particles of particles measuring 0.45 millimeters in diameter, almost 50 times larger than what global winds once thought could transport.

"These dust particles are whipped up from the Sahara desert and transported between continents, and most people know them best when they end up killing our cars or causing the kind of scary orange sky we saw a year ago," explains co-author Giles Harrison, a researcher in atmospheric electricity at the University of Reading.

"However, existing ideas do not allow such massive particles to travel into the atmosphere to such vast distances, suggesting that there is an unknown unknown atmospheric process or combination of processes that keep them airborne."

The bad news is that we can carry underestimation of the winds, we may have cast our climate models seriously.

If large particles, such as quartz, can be transported so wide distances, these materials can be used in spite of both cloud formation and the global climate system.

"This evidence that dust and ashes are borne so far is significant because these particles affect the radiation transmission around the Earth and carbon cycles in the oceans," Harrison says.

Dust may seem like an inappropriate disruption, but if there is enough of it to accumulate in our atmosphere, it can tip a delicate balance, change the entrance to sunlight and heat from the ground.

As they spread and absorb inbound sunlight, these large particles have the power to actually change the clouds, affecting both our planet's weather and climate.

By hanging out in the sky, all this dust can even indirectly affect tropical cyclone development.

The time when all this heavy dust can hang out in the sky is dizzying. And in the end, research suggests that rain, and not only gravity, is responsible for many of the particles that end up falling from the sky.

Weighing such heavy loads carry sour water drops to the deepest parts of the ocean, which further affect the food chains and the carbon cycle of the ocean.

Despite their far-reaching effects, most climate models have so far ignored these big dust particles. The physical laws on which these calculations are based only allows no particles larger than 10 μm to travel so far even at high wind speeds.

There must be something else that keeps these dust particles high – we just do not know what's wrong. And while researchers have explored some explanations, including vertical blending, electrical forces and turbulence, the answer continues to remain uncomfortable.

"The fact that larger particles of dust stop floating in the atmosphere for a long time are considered to be in violation of the physical laws of gravity," says author author Michele van der Does, a researcher at NIOZ.

"We show that by means of a combination of forces and movements in the atmosphere, the big dust pills can actually stay in the atmosphere for a long time and have their influence there."

Now the authors of future climate models encourage the effects of much larger dust particles than ever before.

The research has been published in Scientific progress.


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