HOW IT WORKS
Clouds sprayed with seawater reflect more sunlight, which could help reduce the planet’s temperature.
3 A higher proportion of shortwave radiation from the Sun is reflected by the clouds that have been brightened. This reduces temperatures at the sea surface.
2 When the seawater particles reach the clouds, water vapour condenses around them. The water droplets they form in the clouds are small, resulting in more scattering of incoming light because there are more surfaces for the light to reflect off.
1 Nozzles on board a ship pump tiny particles of seawater into the air. The nozzle already developed by Marine Cloud Brightening Project engineers is capable of generating three trillion particles a second.
Stratocumulus clouds have been identified as the best form of cloud to be brightened. These low clouds extend over huge areas, so offer a much better prospect of affecting temperature than tiny pockets of wispy clouds. And unlike higher clouds, they also allow a relatively high proportion of the longwave radiation reflected from the Earth’s surface to pass through them – they trap little heat beneath them, in other words. LONGWAVE RADIATION Cloud brightening is most likely to take place out at sea. This is because marine clouds tend to have a low reflectivity, giving plenty of scope to boost their reflectivity by injecting them with seawater droplets.