El Niño needed a little help making it rain
This year’s El Niño has been something of a bust in Southern California so far, but the rain over the weekend brought a small bit of relief to the ongoing drought conditions in California. But Mother Nature didn’t soak LA County all by herself. As reported in the LA Times, officials from the Department of Public Works “seeded” clouds in the area, cajoling precipitation out of the clouds that otherwise might have remained in the atmosphere.
The process of seeding involves spraying clouds with silver iodide, which creates crystals of ice within the cloud. Water droplets then form around these crystals and fall as condensation. This may sound like mad science, but it’s technology that has been around a long time—according to the Times, the method has been used since the 1950s, and was most recently employed in 2002. During the 2008 Olympics, Beijing used the technology to disperse rainfall away from the opening ceremony.
In LA, clouds were seeded using generators located along the foothills of the San Gabriel Mountains. Though there is some debate about the effectiveness of this technique, the Department of Public Works estimates that seeding increases rainfall by 10 15 percent, producing an additional 4,500 acre-feet of salvageable stormwater if used over the course of a year. Seeding, however, is only used in specific conditions to avoid accidental flooding.