Scientists have discovered that rain and clouds play a key role in making the air over the Southern Ocean the cleanest on the planet.
Although this Antarctic ocean has less human activity, it is still polluted by aerosols from natural sources, such as salt from the sea, dust from winds or particles from small plant-like organisms called phytoplankton.
But clouds and rain play a key role in clearing the atmosphere over the Antarctic Ocean, researchers say.
Scientists have developed a computer program using data from a new generation of satellites to detect different cloud patterns over vast regions of this ocean.
In particular, the researchers studied the unique honeycomb-shaped cloud patterns known to play an important role in regulating climate.
The honeycomb cells in these special clouds are either “open” or “closed” depending on the amount of precipitation the region they cover receives.
Scientists compared data from the honeycomb cloud analysis with aerosol measurements from the Cape Grim Observatory in Tasmania and rainfall observations from the Australian Bureau of Meteorology.
Scientists have found that the days with the cleanest air are associated with open honeycomb clouds, and suspect that these clouds can “wash” aerosol particles out of the air, creating occasional but intense downpours.
These open clouds seem to hold more moisture and produce more rain than the fluffy white closed clouds.
“We found that clouds with open honeycombs produce 6 times more rain than closed ones,” the scientists wrote in The Conversation.
We found that empty honeycombs are much more common in winter when the air is cleanest.
These honeycomb patterns are also found in the North Atlantic and North Pacific regions during winter, the researchers said.
In future studies, scientists hope to explain how clouds in these regions remove aerosols such as dust and dirt.
