Delhi AQI: Can man-made precipitation purge Delhi's noxious air?

 Delhi AQI: Can man-made precipitation purge Delhi's noxious air?

Could clouds hold the key to solving Delhi's pollution issue?

The environment minister for the Indian capital said last week that his administration was thinking of using cloud seeding, a method of creating rain, to reduce pollution levels as the city struggled with days of unhealthy air.

The permission of many federal ministries and the Supreme Court of India are necessary for the proposal to be implemented. In that case, the plan may be put into action later this month, depending on the weather.

Cloud seeding has been mentioned before as a potential remedy for Delhi's air pollution. However, other experts argue that it is an intricate and costly endeavor whose effectiveness in combating pollution has not been fully shown, and that more study is necessary to fully comprehend its long-term environmental effects.

Nevertheless, political leaders are frantic for a solution as Delhi's pollution continues to choke its citizens and make headlines across the world.

The city's Air Quality Index (AQI), which gauges the concentration of PM 2.5, or small particulate matter, in the air, has continuously above the 450 threshold for the last two weeks, which is over ten times the allowable limit. And although a short period of (natural) rain reduced pollution over the weekend, Monday's air quality deteriorated once again due to people setting off firecrackers in celebration of the Diwali holiday.

Delhi has year-round pollution because to a number of reasons, such as significant industrial and traffic emissions and dust. However, in the winter, low wind speeds and burning agricultural residues by farmers in neighboring states cause the city's air to become particularly poisonous.

The Delhi government has prohibited building and early declared the winter vacations for schools. Additionally, it anticipates receiving approval for cloud seeding from the Supreme Court, which is now considering cases pertaining to Delhi's polluted air.

Is cloud seeding a thing?

A method called "cloud seeding" accelerates the process of moisture condensing in clouds to produce rain.

Using aircraft or ground-based dispersion equipment, salt particles such as silver iodide or chloride are sprayed onto clouds.

The ice crystals in the clouds are made possible by the salt granules, which function as ice-nucleating particles. After adhering to these ice crystals, the cloud moisture turns into rain.

However, the method isn't always effective.

No play, no school, as Delhi's air pollution chokes

Delhi's poor air reduces life expectancy by ten years, according to a research

According to Polash Mukerjee, an independent researcher on the relationship between air quality and health, the atmospheric conditions must be ideal.

"Clouds should have the proper moisture and humidity content to allow ice nuclei to form," he adds, emphasizing the importance of other variables like wind speeds, which may be particularly strong in Delhi at this time of year.

In addition, according to weather expert JR Kulkarni, the salt particles must be blown into a particular kind of cloud that develops vertically rather than horizontally, as reported by Down to Earth magazine in 2018.

There have been decades of this rain-making process. Indeed, it was tested in 1952 by climatologist SK Banerji, the nation's first Indian director general of meteorology.

The US military used the controversial tactic in the 1960s to prolong the monsoon over certain regions of Vietnam in an effort to obstruct Vietnamese military supplies throughout the conflict.

Several Indian states, as well as nations like China and the United Arab Emirates, have tried using the technique to increase rainfall or address drought-like conditions.

What is the goal of the government in Delhi?

Researchers from the prestigious engineering institution Indian Institute of Technology (IIT) Kanpur have submitted the project's proposal.

The project is scheduled to be completed in two stages, the first of which would include around 300 square kilometers (116 square miles). The project should be carried out on November 20 and 21, according to experts, since those days would have the best weather.

The project's principal scientist, Manindra Agrawal, told Reuters that while they didn't anticipate enough clouds to completely cover Delhi on certain days, "a few hundred kilometers would be good."

Does it really have any effect on pollution?

The reasoning for this is that precipitation might aid in clearing the atmosphere of particle matter, improving air quality and breathableness.

Last week, Delhi saw this firsthand as short bursts of rain on Friday and Saturday reduced the amount of smog.

However, many question if artificial rain would really be beneficial.

According to Mr. Mukerjee, cloud seeding has proven "episodic at best" in other nations for controlling air quality and suppressing dust.

When it comes to rainfall's effect on air quality, it lowers pollution levels right away, but within 48 to 72 hours, those levels stabilize and rise again. According to him, cloud seeding is costly and using limited resources on something that won't have a long-term or definitive impact is just a temporary fix.

He continues by saying that it has to be a topic of well considered policy. "An impromptu choice is not acceptable. You need to put in place a number of procedures and have a multidisciplinary team that includes epidemiologists, meteorologists, and specialists in air quality policy to create them."

Concerns over the process's unknowns are shared by certain specialists.

"As of now, there is a lack of significant empirical data regarding the extent to which cloud seeding will lower the AQI," notes climate change and sustainability specialist Abinash Mohanty.

"We also don't know what its [cloud seeding] effects are as through the end you're trying to alter natural processes and who is bound to have limitations," he continues.

He claims that relying just on "meteorological variables like rainfall and windspeed" is insufficient to address pollution.

"We need to make greater cooperation to curb air pollution than piecemeal trial-and-error experiments."