Artificial rain is used in an effort to reduce pollution levels in Lahore, Pakistan.
The capital of the eastern province of Punjab (Punjab), near the border with India, has the world's worst air quality, which is extremely polluted due to its growing population of more than 13 million people.
By early December, air quality in the city had deteriorated so much that schools, markets and parks were closed for four days. By last weekend, the city's air quality index (AQI) had reached levels considered extremely hazardous to health.
To try to reduce dangerous levels, on Saturday the Punjab government used cloud seeding to generate rain at 10 locations around the city using a small Cessna plane.
In order for the clouds to form, there had to already be enough moisture in the clouds that were in the lower atmosphere.
So in the summer, common table salt mixed with water is sprayed over cloud trails by airplanes.
After a few hours, the mixture becomes embedded in the clouds and begins to produce rain.
In winter, clouds are sprayed using flakes of silver iodide, which can be launched from a vehicle or an airplane. This practice, also known as "blueskying", has been used to induce rainfall in many Middle Eastern countries, as well as in China and India.
