‘Artificial rain via cloud-seeding will wash away pollutants, just like normal rain does’

What is cloud-seeding and how it helps in curbing air pollution?

Cloud-seeding is the process of spraying salt mixtures in clouds that would result in condensation of the cloud and eventually cause rainfall. The artifical rain will then wash away pollutants that are suspended in the atmosphere, the same way how rainfall carries out the process of natural cleansing of the environment.

How effective is this process ? Can this be a permanent solution when it comes to tackling air pollution ?

The efficacy of cloud-seeding is equal to the results produced by natural rainfall. We have seen recently in both Delhi and Mumbai how the overall air quality deteriorated. However, following unseasonal rains, the air quality of both cities improved significantly for sometime. In a similar way, artifical rain will bring temporary relief from pollutants in the air, but it can get worse if the sources of pollution aren’t controlled…A permanent solution would be to keep a check on the activities that increase pollution levels.

How do you identify the clouds and how does the process start?

The entire process depends on the availability of clouds. We need to look at the weather radar system, where we get details about cloud presence over a particular geographical area. Also, information given to us by the India Meteorological Department (IMD) helps us get an estimate of moisture content in the cloud. Besides this, the wind direction also needs to be monitored because this factor affects the moisture presence. We also check the density of clouds and calculate the area in landmass that artificial rainfall can cover.

How will this process be effective in Mumbai?

The entire process depends on the clouds’ characteristics and depth above a particular area. We don’t create rain out of thin air. The process involves clouds to shower rain through artificial intervention. The quantum of water depends on the size of the clouds and moisture present in them. If there is good density of clouds, the result will be good.

What are some of the logistical requirement for this process ? And what is the cost ?

The entire process requires a slew of permissions from the government and administration. For example, the Airport Authority of India (AAI) issues a flight pass that allows us uninterrupted take off and landing from a particular spot. In cities like Delhi, which houses a large number of VIPs, we would require an additional permission from the Ministry of Home Affairs (MHA). Also, clearances from local governing agencies could also be required in some places.

For this kind of project, we need to use small carrier aircraft as the particles are needed to be spread in the clouds from a very slow speed. The cost of cloud seeding is around Rs 1,00,000 for every square kilometre of clouds seeded.