"Bengaluru witnesses the driest April since 1983".
"Dubai floods in April 2024 take the lives of 4 people."
I came across these headlines a few weeks back. Though contrasting and bewildering these sound, the anomalies, sadly, are the truth of the times. However, with rain finally coming in Bengaluru this month, the city again witnessed water deluge in several areas. It reminded me of the 2022 floods in the Indian Silicon valley. But yes, it brought much respite from the hot weather.
Ironically, people prayed for rain to keep at bay during the much anticipated and climactic CSK v/s RCB match on 18th May. And the GODS didn’t disappoint the devout at all. The epic clash will be remembered for time to come, for the reasons known to one and all. The very next day, it rained cats and dogs; washing out our society cricket tournament (thankfully, we have a reserve day ahead!!). Never ever since my childhood, I had ever wished rain to stop, and with that fervour last Sunday.
Back to the Headline on Dubai flood: It was really harsh. People were locked to their homes for a couple of days. There were floods in the other Middle East nations- Oman, Saudi Arabia, as well. While initially, the deluge was attributed to 'Cloud seeding', the researchers cohort from the US, the UK, France, KSA, Canada, etc. negated the perception and in fact put the ownership on El Nino. Cloud seeding, was in fact, not done in these areas and the rainfall was pretty much anticipated days in advance, unlike the case where seeded clouds make an immediate downpour. But what exactly is Cloud seeding, how is it done and is it really effective? Read on to know more.
What is Cloud seeding?
In simple language, introducing chemicals in clouds to increase the chance of rain/snow (called precipitation) is called Cloud seeding. The chemicals used in the process primarily are Iodides of Silver(AgI) or Potassium (KI), Dry ice (CO2), Sodium Chloride (NaCl), Sulfur Dioxide (SO2) and Propane (C3H8), Calcium Chloride (CaCl2).
Going a bit technical: Cloud seeding helps enhance the cloud precipitation efficiency by modifying the weather. Cloud precipitation efficiency is defined as the ratio of amount of rain reaching the ground to the amount of water vapor entering the cloud base; the ratio which the chemicals introduced in clouds tries to elevate beyond 1.
The chemicals are introduced in the clouds through aircraft or shot up from the ground through ground-based generators, or rockets, targeting clouds with the potential to generate rains. Once into the atmosphere, the seeding agents facilitate the aggregation of water vapor or supercooled water particles, leading to the development of larger precipitation particles and ultimately increasing rainfall or snowfall rates.
Types of Cloud Seeding
Primarily, there are two cloud seeding techniques: Hygroscopic and Glaciogenic.
Hygroscopic means absorbing moisture from the air. This method is used in warmer clouds using Calcium Chloride (CaCl2) compound for seeding. The chemical, when sprayed on the clouds, leads to coalescence (or accumulation) in water droplets, forming larger droplets which then come down as rain.
Glaciogenic, meaning giving rise to glaciers, is a seeding technique used in cooler clouds. AgI or Silver Iodide is mainly used in this process to form ice crystals in clouds, which then grow and fall as precipitation.
How effective is Cloud Seeding?
Effectiveness of cloud seeding is a much debated topic. Certain factors, like cloud type, temperature, humidity, and wind conditions define the precipitation level and hence the benefits of the process. While the critics and the proponents put forward their arguments on the efficacy, several governments across the world are using it to bring showers to arid regions or to fight wildlife fires. An example is the impact in Solapur, Maharashtra, where cloud seeding increased rainfall by 18%, as per Bulletin of the American Meteorological Society (BAMS) study. But we can’t solely rely on Cloud seeding to be our saviour always. In a recent hearing on the Uttarakhand forest fires, the Supreme Court of India stated to the State Government: 'Rain gods and cloud-seeding are not the answers to forest fires. You have to take preventive measures'.
The remark from the Honourable Court perfectly summarizes the need of the hour and rightly puts the onus on all of us to combat climate change and global warming. Whether cloud seeding is effective or not, we have to protect the Earth's green cover and save water. Reduce, Reuse and Recycle. ♻️
Nerd Notes:
- Not all types of clouds are good for seeding. Clouds must be deep enough and of a suitable temperature to be seeded effectively.
- Glaciogenic cloud seeding is usually applied to convective clouds, or winter orographic clouds.
- The first instance of cloud seeding experiment dates back to 1946; conducted by American chemist and meteorologist Vincent J. Schaefer.
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Good job Prakhar
ReplyDeleteVery informative prakhar
ReplyDeleteNice, put in simple words, easy to understand and very informative
ReplyDeleteHeard about cloud seeding but the simple and detailed description about the chemical engineering in the seeding made it easy for us to understand. Great job Prakhar.
ReplyDelete