Tiny Airborne Particles May Have Huge Impact On Storms

A new study has found that tiny airborne particles from industrial air pollution can have a bigger impact on powerful storms than scientists previously thought.

The study, published in the journal Science, describes the effects of aerosols, which can come from urban and industrial air pollution, wildfire and other sources.

“This result adds to our knowledge of the interactions between aerosols, clouds, and precipitation. In areas where aerosols are otherwise limited, such as remote regions of the Amazon rainforest, ultrafine aerosol particles can have a surprisingly strong effect,” said co-author of the study Zhanqing Li, Professor at University of Maryland in the US.

The researchers studied the storm-creating capacity of ultrafine particles that measure less than 50 nanometers across.

According to the researchers, larger particles are known to play a role in feeding powerful, fast-moving updrafts of air, which create clouds that form water droplets that fall as rain. But until now, researchers had not observed smaller particles, such as those contained in vehicle exhaust and industrial smog, exerting the same effect.

Using detailed computer simulations, the researchers showed how smaller particles can invigorate clouds in a much more powerful way than their larger counterparts when specific conditions are present.

In a warm and humid environment with no large particles to attract airborne moisture, water vapour can build up to extreme levels, causing relative humidity to spike well beyond 100 per cent.

While ultrafine particles are small in size, they can reach large numbers. These particles form many small droplets that quickly and efficiently draw excess water vapour from the atmosphere, the researchers said.

This enhanced condensation releases more heat, which makes the updrafts much more powerful. As more warm air is pulled into the clouds, more droplets are launched aloft, producing a runaway effect that results in stronger storms, the researchers added.

“This finding will help us better understand the physical mechanisms of cloud development and severe storm formation, which can help us develop better storm prediction methods,” Li added.