With the Middle East and North Africa drying up, countries in the region have embarked on a race to develop the chemicals and techniques that they hope will enable them to squeeze rain drops out of clouds that would otherwise float fruitlessly overhead.
Key highlights
- The United Arab Emirates (UAE) has been leading the effort to seed clouds and increase precipitation, which remains at less than 100 millimetres (3.9 inches) a year on average.
- The UAE uses two seeding substances: the traditional material made of silver iodide and a newly patented substance developed at Khalifa University in Abu Dhabi that uses nanotechnology that researchers there say is better adapted to the hot, dry conditions in the Persian Gulf.
- Scientists in Abu Dhabi combine shooting hygroscopic, or water-attracting, salt flares with releasing salt nanoparticles, a newer technology, into the clouds to stimulate and accelerate the condensation process and hopefully produce droplets big enough to then fall as rain.
- Other countries in the region, including Saudi Arabia and Iran, have announced similar plans as they face historic droughts.
What is Cloud Seeding?
- In the 1940s, atmospheric scientist Bernard Vonnegut found that particles of silver iodide can cause supercool clouds of water vapor to freeze into snow in the lab.
- Cloud seeding is a weather modification technique that improves a cloud’s ability to produce rain or snow by introducing tiny ice nuclei into certain types of subfreezing clouds.
- These nuclei provide a base for snowflakes to form. Most cloud seeding operations use a compound called silver iodide (AgI) to aid in the formation of ice crystals.
- Silver iodide exists naturally in the environment at low concentrations, and is not known to be harmful to humans or wildlife.
- Upon reaching the cloud, the silver iodide acts as a condensation nuclei to aid in the formation of snowflakes.
- Cloud seeding is used all over the world as a method for enhancing winter snowfall and increasing mountain snowpack, supplementing the natural water supply available to communities of the surrounding area.
