Cloud seeding.

Saudi Arabia has launched a cloud seeding project over three areas to boost rainfall. The country has begun the first phase of a cloud seeding operation using chemicals. To do this, small particles of silver iodide are injected into existing clouds, around which drops of water then collect. Colliding with each other, the drops increase in size - and this, in turn, increases the likelihood of rain. With its help, the country expects to increase the amount of annual precipitation by 10-20%.