Mitsubishi Heavy Industries is preparing to prime nature’s pump with a 50-square-kilometer oasis on Saudi Arabia’s Red Sea Coast. A large volume of moist air flows through the atmosphere over the region. Computer simulations suggest that verdure on the ground could promote cloud formation and rainfall. That could be the beginning of a self-sustaining cycle of greening and precipitation.
   Project planners at Mitsubishi Heavy Industry are working out the outlines of their vision with the Saudi government. They hope to begin building a desalination plant in three years to supply water for the initial plantings. Meanwhile, they are refining pertinent technologies in cooperation with Japanese government agencies and universities in an ongoing water resources program.
   The planning under way for the Saudi project is drawing a great deal of attention internationally. Government agencies in China and in other nations that contend with chronic water shortages have expressed interest in undertaking similar projects. Bring an umbrella.