Context: Delhi is planning to induce artificial rains to tackle the rising air pollution.
Brief about cloud formation
- Clouds are made up of tiny water droplets or ice crystals that form when water vapor in the atmosphere cools and condenses around a tiny particle of dust or salt floating in the atmosphere.
- Without these particles, known as condensation or ice nuclei, raindrops or snowflakes cannot form, and precipitation will not occur.
- Cloud seeding is an artificial method used to increase rainfall by introducing certain substances into clouds.
- During cloud seeding, chemicals like silver iodide, potassium iodide, and dry ice are released into the sky using airplanes and helicopters.
- These chemicals attract water vapour, leading to the formation of rain clouds.
- It usually takes about half an hour for this method to make it rain.
Techniques of cloud Seeding
According to the ScienceDirect, cloud seeding techniques can be divided into two categories:
1. Hygroscopic cloud seeding aims to accelerate the coalescence of droplets in liquid clouds, resulting in the formation of larger droplets that lead to precipitation.
- The seeding agents used in hygroscopic cloud seeding serve as efficient cloud condensation nuclei (CCN) or GCCN and play a crucial role in strengthening the condensation and collision–coalescence process, thereby widening the droplet size distribution (DSD) and increasing the precipitation efficiency.
2. Glaciogenic cloud seeding, focuses on inducing ice production in supercooled clouds, leading to precipitation.
- Glaciogenic cloud seeding involves dispersing efficient ice nuclei, such as silver iodide particles or dry ice, into the cloud, which enhances ice particle production and increases rain.
Utility of Cloud Seeding
That serves various purposes, including:
- Reducing the impact of droughts
- Preventing forest fires
- Increasing precipitation
- Enhancing air quality.
Success story of cloud seeding
A cloud seeding experiment carried out in Solapur city, which falls on the leeward side of the Western Ghats and hence gets low rainfall, was able to achieve 18% relative enhancement in rainfall.