Mexico City uses technology to make its own wind and rain. But the sceptics are not impressed
mexico City, the most polluted city on the planet, is considering radical methods to clean up its act. Travellers to Mexico's capital city often fail to see it from air as it is usually shrouded by smog throughout the year. This has cost the city dearly, with many of its people suffering from pollution-related diseases. And after decades of living under a perpetual haze, the city authorities are planning to control its weather in an attempt to clean the city up. They are testing an antenna system designed to bring about changes in the local rainfall and wind patterns. The sceptics, however, are not very impressed.
The antenna ionises the atmosphere, creating nuclei on which water vapour can condense. Physicists Lev Pokhmelnykh of the Mexican firm Electrificacin Artificial de la Atmosfera and Gianfranco Bisiacchi of the National Autonomous University of Mexico are now testing the antenna. According to the Latin American media, the researchers believe that air currents will change their directions and intensity once the heat released during condensation warms the air.
Using an array of antennae to either create or neutralise ions, they hope to influence local rainfall and wind patterns. Since most of the city lies within a valley, wind and rain can help disperse air contaminants that frequently attain high concentrations within the confines of the surrounding mountains. However, Sherwood Roland of the University of California at Irvine, usa , who won a Nobel prize for his work on atmospheric chemistry, says natural radioactive materials decay and ionise the air continuously. Within a cubic centimetre of atmosphere, some 3,000 free electrons are generated every second. So any attempt to alter the natural level of ionisation would need to add or remove an enormous number of electrons.
Donisio Moreno, a physicist in Mexico's environment department and a member of the government committee that is currently evaluating the project, is sceptical. He says they are still unable to see any clear, perceptible change in the intensity or the direction of the winds produced with the help of the antennae. Preliminary results are insufficient, he says. The latest results, presented by Pokhmelnykh and Bisiacchi on January 15 this year, are still to be analysed.
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