Is it possible to change the amount of rain an area receives by interacting with clouds?
Celine Gadoua
No. At least not with a predictable success rate.
But that could change in the next decade, according to Sarah Brooks, a chemist at Texas A&M University, who just published in the journal ACS Earth and Space Chemistry a study showing that pollen can affect the ability of clouds to generate rain.
“In recent years, the ability to count ice nuclei in clouds has been greatly improved (ice nucleating particles or INP), explains Mme Brooks. We also realized that it is not only dust that makes ice nuclei, but also biological particles such as pollen. »
Clouds get bigger thanks to ice nuclei, which increase the amount of ice in the clouds and their size. “Most rain clouds contain ice,” says Ms.me Brooks.
“Cloud seeding” projects (cloud seeding) with INPs exist in China, the Middle East and Texas. In this US state, the government claims that seeded clouds give 24% more rain, but this data should be taken with a grain of salt because it is not published in peer-reviewed journals (peer review), according to Mme Brooks. Cloud seeding involves sprinkling clouds with INP from an aircraft.
PHOTO FROM TEXAS A&M UNIVERSITY WEBSITE
Sarah Brooks, chemist at Texas A&M University
The problem with current cloud seeding programs is that they take on a new technology, a new INP, as soon as there appear to be positive results in the lab. Afterwards, we tell ourselves that it works if it rains, and we shrug our shoulders if it doesn’t work. To really get to the bottom of it, you would have to apply a treatment to 100 clouds and compare them to 100 comparable clouds. But no one has that patience.
Sarah Brooks, chemist at Texas A&M University and author of a study showing that pollen can affect the ability of clouds to generate rain
One promising avenue is the study of “inadvertent cloud seeding”. “For example, we look at the air pollution of a city and we try to find correlations with the amount of rain,” says M.me Brooks. This allows you to find new INPs. »
Recent years have shown that biological PNIs probably play a more important role than dust at warmer temperatures (between 0 and -15°C), according to M.me Brooks. She published this year in the journal Communications Earth & Environment a study reporting the ability as an INP of RuBisCO, an enzyme found in photosynthesizing organisms that can travel through the atmosphere. “Biological particles can travel very far,” says Ms.me Brooks. A study with the lidar in Colorado made it possible to observe pollen particles in the clouds at an altitude of more than 8 km. Lidar is a type of radar.
These advances suggest that Mme Brooks that cloud seeding will become a reality within the next decade if the research is properly supported. “Then there will be difficult negotiations. The amount of water in the atmosphere is not infinite. If it rains somewhere, it won’t rain elsewhere. One could see treaties of “rights of withdrawal” of atmospheric water as it exists for the large rivers, for example the Colorado. »
Learn more
-
- 311
- Number of cloud seeding missions in the United Arab Emirates in 2022
Source: Wired