Clouds as Transformational Tools

Sahel Region, Africa

Chung-Wei Lee

Based on principles of cloud formation, this project is an exploration into the possibilities of mitigating conditions in extremely dry, desert areas using the Earth’s ground water resources to generate clouds. The locus of this exploration is the Sahel region in the Sahara. The Sahel region is a grassland belt that stretches across the African continent from the Atlantic Ocean to the Red Sea, which divides the vast, dry Sahara desert and the wet tropical rain forest. Its savannah ecosystem and agriculture activities depend on the precarious rainfall causing this region to be permanently threatened by food scarcity and desertification on the south Sahara fringe. At the same time, a trans-boundary fossil aquifer system—one of the world’s largest groundwater systems—lies beneath the sandstone stratum covering the Sahara and Sahel. Most of these aquifers were recharged 5,000 years ago when the climate was tropical.

A new type of irrigation system reaching to the underground aquifer system is proposed to re-activate the water cycle over that region. This new system acts as a literal “cloud machine” that captures water vapor and triggers rainstorms. The heat and flatness of the landscape allow soil moisture patterns to trigger ground winds that favor the development of convective cumulus clouds—the cardinal engine that brings water vapor into the air, forming clouds, and resulting in rainfall. At a regional scale, these artificial patterns of soil moisture not only efficiently use the water vapor from the croplands’ evapotranspiration but also capture the moisture brought by southwest winds from the southern tropical forests. Clouds become an environmental transformational tool fostering forest growth on the endangered fringe between the Sahel region and the Sahara Desert.

Top: Elevation of the convective cloud formation stages, a water circulation system that traverses the ground and the atmosphere. A water droplet can take several hours to several days to complete a full cycle.

Bottom: Plan of the convective cloud formation stages.