CLOUD SEEDING
WHY IN NEWS ?
- Recently, Delhi government had announced earlier this week that it was considering cloud seeding or ‘artificial rain’ to wash away pollutants in the air.
WHAT IS CLOUD SEEDING?
- Water vapour condenses around small particles to form the droplets that make up a cloud.
- These droplets collide and grow; as they get heavy and the cloud gets saturated, it rains.
- With cloud seeding, clouds are usually injected with salts like silver iodide, potassium iodide, or sodium chloride, which is the ‘seed’.
- These salts are expected to provide additional nuclei around which more cloud droplets can form.
- They are dispersed into the cloud either using aircraft or through generators on the ground.
- Seeding accelerates cloud microphysical processes.
- You need sufficiently large droplets that can reach the surface of the earth and not evaporate on the way.
CONDITIONS REQUIRED FOR CLOUD SEEDING:
- Firstly, cloud cover and clouds of a certain type are necessary.
- Cloud seeding can only happen if there is a sufficient number of clouds and a particular depth to these clouds.
- Inside, there needs to be an adequate number of cloud droplets.
- Cloud seeding is done to increase the radius of the cloud droplets so that they will grow bigger and because of gravity, they will come down as rainfall.
- But with a clear sky, you can’t do it.
- With a stable atmosphere in winter, clouds are expected to form when a western disturbance disturbs this stability of the atmosphere.
- While the possibility of cloud formation can be determined in advance through radars, other conditions will have to be studied on the day seeding is likely to be done.
NEGATIVES OF CLOUD SEEDING:
- The chemicals used in cloud seeding might be potentially harmful to plants, animals, and people, or the environment.
- As artificial rain falls, seeding agents like silver iodide, dry ice or salt will also fall.
- Residual silver discovered in places near cloud-seeding projects is considered toxic.
- The chemicals used in cloud seeding might be potentially harmful to plants, animals, and people, or the environment.
SYLLABUS: PRELIMS, ENVIRONMENT
