How Manmade Clouds Combat Climate Change: Reflecting Sunlight

When it comes to cooling off the planet, clouds have the potential to play a huge role. Now, scientists have identified the most energy-efficient way to make clouds more reflective to the sun, which could help combat climate change.

Clouds form when water droplets gather on tiny particles within the air. In theory, increasing the amount of salt particles in the atmosphere allows more of these water droplets to form, making denser and more reflective clouds.

In this case, the researchers examined four different ways of getting particles into the sky in order to compare how effective they might be.  Previous studies optimized the size of the salt particles needed to produce the best increase in cloud reflectance, but didn't take into account how much energy the technique would need and how much it would cost to operate.

In this case, the researchers found that a method called the "Rayleigh Jet" was the best one. The technique relies on a fine jet of water that breaks down into small droplets in the sky. The liquid droplets evaporate quickly and leave behind only salt particles.

"It can be incredibly energy intensive to propel water high into the atmosphere and the energy required had never really been tested before," said Paul Connolly, one of the researchers, in a news release. "Our paper optimizes the salt particle sizes to produce the required change in cloud reflectance for the least energy cost. It is an important finding if these techniques should be needed in the future. I am not recommending that we use any of these techniques now, but it is important to know how best to use them should they become necessary."

The findings could be important for future efforts to combat climate change. That said, these techniques shouldn't be employed unless necessary. They do, however, present an option that might be used in the future.

The findings are published in the journal Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.