When a recent dust storm gusted down from the barren plains of northern China and deposited more than 300,000 tons of yellow sand and dust on Beijing and its inhabitants, meteorologists at the Beijing Weather Modification Office did what they have been doing for decades — they made their own rain. The storm, reportedly the worst of its kind to hit the region in five years, caused health officials to advise children and people suffering from respiratory ailments to stay indoors. However, in a matter of hours after the rainmaking, the dust had cleared, the sky began to reappear above Beijing, and it was once again safe to venture outside.

How is it possible for Chinese meteorologists to make their own rain? Even though most people would probably guess that the process is highly complex, if not impossible, in fact, it is relatively simple. Meteorologists inject clouds with chemicals in a process called 'cloud-seeding', or simply 'seeding'. How do they inject the clouds? They use rockets. From the rockets, they launch hundreds of sticks of silver iodide, each the size of a cigarette, which begin to draw together the scattered water molecules in the air. Eventually, the water molecules that have gathered around the sticks of silver iodide become too heavy to remain suspended in the air and fall to ground as rain.

For decades, China has relied on cloud-seeding, not only to end droughts, alleviate dust storms and clear away dust, but also to fight forest fires. In fact, in the past five years, it has conducted nearly 3,000 rainmaking missions, producing 210 billion cubic metres of water over an area of 3,000,000 square kilometres. However, the potential and even the validity of the artificial rainmaking technology have yet to be recognised by most other countries around the world. Critics in the scientific community, who remain sceptical of China's rainmaking success, insist on referring to cloud-seeding as an 'unclear' and 'questionable' science. In response, weather specialists in China cite the figures and invite the critics to visit Beijing in the wake of a dust storm, wait for the cloud-seeding to take effect and then go outside and look at the resulting clear sky.

However, not everyone in China is in agreement about how cloud-seeding is being used to make rain. There was a case in recent years where several cities in the drought-stricken province of Henan argued over the clouds being seeded. Despite the fact that the cities of Pingdingshan, Zhumadian, Luohe, Xuchabg and Zhoukou all received much needed rain as a result of cloud-seeding, the amounts that rained down in each city caused disagreement. Pingdingshan received more than 100 millimetres of rain, which helped to alleviate the drought that had been plaguing the city. Neighbouring Zhoukou, on the other hand, received less than 30 millimetres — not enough for the city to fully recover from its dry spell. In protest, officials in Zhoukou accused those in Pingdingshan of 'stealing' rain from clouds that would probably have drifted to other cities, saying: 'They were still launching rockets to make rain when they already had rain falling.' In an effort to resolve the argument, meteorologists pointed out that although cloud-seeding is effective in producing rain, its yields are inexact.

Even though the sometimes unpredictable results of cloud-seeding have become a source of contention within China and the technology remains a debatable topic among scientists around the world, Chinese meteorologists maintain that the results from cloud-seeding speak for themselves. For the 3,000-plus people employed in the rainmaking field throughout China, the technology is not 'unclear' or 'questionable'. To them, the only thing that is unclear or questionable is why the rest of the world is not embracing the technology and making their own rain.

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