Skip to main content

Play stops rain: could 'cloud seeding' deliver perfect Wimbledon weather?

Image credit: Carine06, Wikimedia Commons
Wimbledon, 2026. Bright blue skies and a wonderful late afternoon sun lights up the lush green grass of centre court. Out strides the British number one and four-time winner, Andy Henman, to the cheers of the excitable, partisan crowd.

Somewhere nearby, at the headquarters of WeatherMod Inc, a group of technicians are busily checking data, confident that their efforts have worked. They have been in contact with two pilots who have just completed their spray sorties and are returning to land at Heathrow’s new third runway. Thanks to the delivery of 4kg of, in its pure form, a yellowish powder known as Silver Iodide (AgI) into clouds upwind of London, it is now raining over the Salisbury Plain, 100 miles away, and the rain predicted for later in SW19 is now 92% less likely.

This scenario probably sounds a little far-fetched, and not least the bit about the repeatedly successful home-grown tennis player. However, weather modification occurs more often than most people are aware. For example, as I wrote that first paragraph I genuinely didn’t realise that a Weather Modification Incorporated actually already exists in Fargo, North Dakota. They, and other companies like them have sprung up over the past few years promising to manage water for crops, clear fog and even protect wedding days from ill-timed hail.

But two questions need further investigation to consider the likelihood of the above scenario at Wimbledon: can we do it (that is, does it work) and should we do it? Neither, it turns out, are particularly easy to answer.

Changing the weather


In order to make rain several processes need to occur. First, small particles known as cloud condensation nuclei (CCN) are required onto which water can condense. Then these droplets need to grow to a size where they precipitate out of the cloud, finally falling where and when required.

In our hypothetical scenario we would therefore need to be able to either control or at least predict accurately the concentration of CCN, the rate at which droplets form, and the evaporation rates within the clouds. We’d also also need to have some handle on the rate and direction in which rain would fall.

Silver iodine dumped into a cloud attracts water, which turns into rain. Smcnab386 / wiki, CC BY-SA

In reality, cloud seeding with AgI – the current default option – only really tackles the first of these processes, forming the condensation nuclei. Even if clouds are seeded, it is still a matter of debate as to whether they actually create much additional rain. While companies claim success, some scientists are more wary. Although other seeding agents (and methodologies) exist, it is worth noting that, in the case of AgI, the nature of the clouds into which the particles are injected will govern the outcome.

Seeding works best in clouds which have a pre-existing mixture of water droplets and ice, as this type of nucleation requires ice-crystals to form. Following the production of CCN we’d then need to be able to predict, through computer modelling, how small droplets will form into rain and eventually fall.

One of the major drawbacks of cloud seeding is a lack of proof that it works: given weather forecasting remains imperfect, how would you know what would have happened without intervention? The second part of the question is arguably even harder to approach. What are the ethics of removing water from one part of the world, even on a small scale, and moving it somewhere else? Is this “messing with nature” or “playing God”? Water is, after all, the most precious commodity on Earth.

Let’s assume for now that it is possible to alter local weather patterns and to prevent or cause rain. This could be used for both good and evil, and the potential for abuse is worth considering. While manipulating the weather as a weapon is now explicitly outlawed by the UN’s ENMOD treaty, there have been efforts to alter the outcome of conflict using cloud seeding.

‘Operation Popeye’: the US used cloud-seeding to extend the monsoon season during the Vietnam war, causing delays on the waterlogged Ho Chi Minh Trail. manhhai, CC BY

Deliberate and accidental effects from commercial activity also seem possible. That dreamy, rain-free wedding ordered up by an anxious billionaire could easily ruin a school sports day in a nearby town.

The question of attribution is possibly the most challenging. Without any alternative outcomes to analyse, how can you really know what are the impacts from your actions. Some even say, quite incorrectly, that cloud seeding experiments caused floods, such as those that killed 35 people in the English village of Lynmouth in 1952. Expert opinion leans strongly against that idea being correct. Nonetheless, conspiracy theories persist. If, in our hypothetical Wimbledon scenario, bits of Wiltshire flooded, who would foot the bill?

It’s certainly possible in theory to prevent rain in one place by using cloud seeding to induce it in another, upwind. But there are huge challenges and the jury is still out about whether such efforts really work.

There are some very good causes, such as inducing rainfall in Sub-Saharan Africa during drought, where I would sanction intervention. For something as frivolous as a sporting event I feel differently. Just last weekend I played cricket for four hours in unrelenting drizzle (thanks Skip). While not a massively enjoyable experience it was at least familiar, and is part of the essence of both cricket and tennis. There’s some comfort in that.

----------------------------------------------------
The Conversation
This blog is by Matthew Watson, Reader in Natural Hazards at the University of Bristol.
This article was originally published on The Conversation. Read the original article.
Matthew Watson

Comments

Popular posts from this blog

The Diamond Battery – your ideas for future energy generation

On Friday 25th November, at the Cabot Institute Annual Lecture, a new energy technology was unveiled that uses diamonds to generate electricity from nuclear waste. Researchers at the University of Bristol, led by Prof. Tom Scott, have created a prototype battery that incorporates radioactive Nickel-63 into a diamond, which is then able to generate a small electrical current.
Details of this technology can be found in our official press release here: http://www.bristol.ac.uk/news/2016/november/diamond-power.html.
Despite the low power of the batteries (relative to current technologies), they could have an exceptionally long lifespan, taking 5730 years to reach 50% battery power. Because of this, Professor Tom Scott explains:
“We envision these batteries to be used in situations where it is not feasible to charge or replace conventional batteries. Obvious applications would be in low-power electrical devices where long life of the energy source is needed, such as pacemakers, satellite…

Dadaism in Disaster Risk Reduction: Reflections against method

Reflections and introductions: A volta The volta is a poetic device, closely but not solely, associated with the Shakespearean sonnet, used to enact a dramatic change in thought or emotion. Concomitant with this theme is that March is a month with symbolic links to change and new life. The Romans famously preferred to initiate the most significant socio-political manoeuvres of the empire during the first month of their calendar, mensis Martius. A month that marked the oncoming of spring, the weakening of winter’s grip on the land and a time for new life.
The need for change Having very recently attended the March UKADR conference, organised by the Cabot Institute here in Bristol, I did so with some hope and anticipation. Hope and anticipation for displays and discussions that conscientiously touched upon this volta, this need for change in how we study the dynamics of natural hazards. The conference itself was very agreeable, it had great sandwiches, with much stimulating discussion …

Localising the Sustainable Development Goals for Bristol

In 2015 the 17 UN Sustainable Development Goals (SDGs) were ratified by 193 of the UN member nations. These goals set ambitious targets to address worldwide issues of sustainable development, such as social inequality, responsible and inclusive economic development and environmental protection. They were created for everyone, everywhere and have been described as ‘the closest thing the world has to a strategy’.

Who will be responsible for ensuring we achieve these goals and how will they be achieved?
In the realm of international agreements, national governments have traditionally been responsible for local implementation. But a combination of profound global demographic shifts and a sense that national governments are increasingly incapable of tackling complex global challenges due to domestic political wrangling has given rise to a global movement to place cities at the heart of efforts to tackle both local and global challenges.  This movement, which is coalescing around a constel…