Cloud Seeding

What do you understand by cloud seeding? Explain the science behind it, its applications and its usefulness for India. (200 Words)

Cloud seeding is an artificial technique of inducing the clouds to yield rainfall.
SCIENCE INVOLVED
It is based on the scientific principle that moisture, to convert into rainfall, needs two things:
  1. A hygroscopic nuclei and
  2. A critical size of water droplet so that it reaches earth surface without being evaporated.
This is done by spewing hygroscopic nuclei like Silver iodide, Common salt and moisture in the clouds to facilitate and speed up the accretion of water droplets or ice crystals to achieve sufficient droplet size that can fall on the earth.
Cloud seeding is done by two process:
  1. Hygroscopic Seeding: To get rainfall.
  2. Glaciogenic Seeding: To get snowfall or hail.
APPLICATIONS
  1. Agriculture: Inducing cloud to precipitate and break dry spell helps manage sowing and prevent crop wilting. Glaciogenic techniques can be used to reduce size of hail stones and check crop loss.
  2. Water management: Getting rainfall at places with adequate water harvesting and storage capacities can prevent both droughts and floods.
  3. Event management: Uses like one done during London Olympics by seeding cloud before they reach stadium, can prevent washing of events by rainfall.
  4. Glacier restoration: Glaciogenic techniques can help restore the mass of depleting glaciers.
USEFULNESS TO INDIA
Indian socio-economic setup is vitally linked with Monsoon which is highly erratic causing agrarian and economic crises. Cloud seeding can manage this uncertainty of rainfall. Crop loss in Vidharbha due to hail storms can be mitigated. Moreover It can augment Namami Ganga program by restoring the mass of Gangotri glacier. Floods and drought can also be mitigated.