Those of us who follow cricket have heard, countless times, that the ball swings more under overcast skies.
This is common knowledge that has been around for a very long time. Almost everyone involved in the game is aware of the phenomenon and cites it frequently, especially when the action is taking place in England where bad weather is a frequent threat.
Swing bowlers smile and lick their lips at the thought of bowling under cloud-laden skies; batters worry about playing and missing and searching and not finding balls that seem to swerve at the last moment. So yes, the relationship between overcast conditions and swing is established cricket knowledge. It has been for a long time.
Except, it’s not true. There is no relationship between cloud cover and a cricket ball’s inclination to deviate in the air.
Aerodynamics experts such as Dr. Rabi Mehta, for example, former NASA scientist and former new-ball partner of cricket legend Imran Khan have carried out studies that have long established that overcast conditions do not accentuate swing.
And despite years of publications and interviews on the matter, his findings have fallen overwhelmingly on deaf ears.
Many fans and pundits, including some who are aware of Dr Mehta’s work, remain convinced that there is a connection between swing and the weather.
On this topic, many of us in cricket are like members of the modern flat earth societies, who hold that the earth is flat and not a sphere despite mountains of evidence to the contrary.
Many of us refuse to accept science when it collides with our long-held beliefs or when it contradicts some view we are invested in and have espoused over a long time.
Take, for instance, the long-held idea that arthritis sufferers feel more pain in cold weather. It is not true and researchers have long proven that there is no connection between arthritis pain and temperature.
But many arthritis patients, even those who are aware of the research, remain convinced there is some correlation. Even when renowned researchers, Don Redelmeier and Amos Tversky showed patients the evidence, the vast majority of them still clung to their old belief.
Citing Redelmeier’s and Tversky’s research, Michael Lewis, of Moneyball fame, writes in his book, The Undoing Project, that patients used a few random moments to underpin their belief.
“For arthritis, selective matching leads people to look for changes in the weather when they experienced increase pain, and pay little attention to the weather when their pain is stable... [A] single day of severe pain and extreme weather might sustain a lifetime of belief in a relation between them,” Lewis wrote.
Selective matching is also what many of us in cricket do. We remember it swinging on a murky morning in Leeds, but forget it swinging just as much on a sunny afternoon in Barbados.
The 1972 Lord’s Ashes Test is recorded in history as Massie’s Match. Why? Because the Australian seam bowler, in a masterful exhibition of swing bowling, totally dismantled the home side with match figures of 16 for 137.
Waking up that morning, the bowler was happy to see “greyness” outside his window, “I knew it was going to be a day that if I, you know, bowled fairly well, I should get wickets because it was one of those tailor-made days for swing bowling,” Massie said.
Though there are studies dating back to the 1950s contradicting the swing/weather association, Massie might not have known about them. But, cricket pundits nowadays ought to know better, especially since many of them are well aware of the studies that have been done on the matter and have had conversations with researchers like Mehta.
Additionally, no less an expert than former England fast bowler Jimmy Anderson, taker of 704 Test wickets and the man who was the game’s foremost practitioner of the art, had this to say on the matter in an ECB video from 2015.
“There have been days when the sun is out and the ball swings and some days when it is freezing cold at the end of April and it swings. I couldn’t tell you when it is going to swing, NO!” he said.
Studies done on the question of what causes a cricket ball to swing have all yielded the same result: it matters not one jot whether it is cloudy or clear or humid or dry. The swing generated has nothing to do with the weather.
Dr. Mehta, in an article for a special physics edition of Teacher Plus magazine, wrote this.
“How many times have you heard cricket commentators refer to humid or damp conditions as constituting a ‘heavy’ atmosphere? This implies an increased air density and it turns out that the side force on a cricket ball is directly proportional to the air density,” he wrote.
“Well, the fact is that humid air is actually less dense than dry air.”
This should have been more than enough to debunk the idea that humid air aids swing, and yet the idea lives.
It turns out, however, that there is a slight relationship between swing and temperature. Cold air is denser than hot air and so we should ignore cricketers and pundits whenever they say “it is too cold to swing.”
“The air density is higher on a cold day compared to that on a hot day,” Dr Mehta wrote.
“However, the dependence is not very strong with the air density being only about 4% higher at 15 degrees Celsius compared to that at 25 degrees Celsius.
“This means that a ball which swings about 2 feet at 25 degrees Celsius will deviate about another inch at 15 degrees Celsius. This is obviously not enough to explain what is observed on a cricket ground.”
Swing is indeed a troublesome subject and the misapprehensions about what causes a cricket ball to swing are many.
But the evidence suggests that the weather conditions so often mentioned by commentators and cricketers have little or no meaningful effect on the cricket ball’s tendency to swing.
The overcast conditions that make fast bowlers smile and batters nervous may therefore have more to do with psychology or cricket mythology than aerodynamics.
