WEATHER-SWING CORELATION

No such thing as fair weather for swing

by Garfield Robinson • Published on

India's batting implosion on Day 1 of Lord's Test was put down to the overheads. © Getty

Arthritis sufferers feel more pain in cold weather. This is something almost everyone knows. This knowledge, according to Michael Lewis in The Undoing Project "could be traced back to Hippocrates, who wrote, in 400 BC, about the effect of wind and rain on disease." Doctors regularly recommended that arthritis patients move to warmer climates and I have met many Jamaicans who lived in England for a long time who claimed that one reason they moved back was because of arthritis.

Only, researchers have long proven that there is no connection between arthritis pain and the weather. It is simply not true that patients stricken with the disease feel more pain when the temperature drops, though many of them are convinced of this. Even after showing patients proof, as researchers Don Redelmeier and Amos Tversky did, the vast majority of them still clung to the belief that their level of pain had something to do with the weather.

Reporting on Redelmeier's and Tversky's research, Lewis writes that patients used a few random moments to underpin their belief. "For arthritis," wrote Tversky and Redelmeier, "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."

In cricket, there is a strongly held belief that the ball's tendency to deviate through the air is affected by the weather. The ball swings more, it is believed, in moist conditions under cloudy skies.

Only, this is not true either. Aerodynamics experts, such as Dr. Rabi Mehta, NASA scientist and former new-ball partner of cricket legend and current Pakistan Prime Minister, Imran Khan, have long established that overcast conditions do not accentuate swing. And despite years of studies, publications, and interviews on the matter, his findings have fallen overwhelmingly on deaf ears.

Fans and pundits alike, some of whom who Dr. Mehta has had conversations with personally, remain convinced that there is a connection between swing elicited 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 truck-loads of evidence to the contrary.

Like many arthritis sufferers, we engage in selective matching. Those who argue that there is a correlation between swing and weather, have tended to latch on to instances that confirm the theory while ignoring instances that seem to contradict it. We are quick to recall the occasions when the ball swung under cloud-laden skies in Headingley or Lord's, but forget the days when it went through gun-barrel straight in similarly dank conditions. Or, we remember James Anderson swinging it on a muggy morning at Lord's against the hapless Indians, and forget that Jason Holder recently swung it probably just as much, recently, on a bright afternoon in Barbados.

Dr. Mehta is of the view that swing on a cloudy day could be fostered by some kind of self-fulfilling prophecy. The bowler who thinks it swings more on a cloudy day will focus more on swing once there is cloud cover overhead. He might, for example, try to deliver the seam in an upright position, or choose to bowl a fuller length to offer the ball more time to swing.

Australian fast bowler Bob Massie swung the ball expertly at Lord's in 1972 to capture 16 wickets for 137 runs. The game is often referred to as Massie's match and it was a clinical exhibition by a skilled craftsman. 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 might not have known -- though there are studies dating back to the 1950s -- that there is no real connection between swing and the weather. But, the cricket community nowadays ought to know better.

How many times during the recent Lord's Test did we witness TV analysts, print journalists and fans on twitter refer to the damp conditions that prevailed when India batted as facilitating the considerable swing generated by Anderson and his comrades? Many of them have come across the science that totally contradicts this notion yet choose to reject or ignore it.

Numerous studies have been done on the subject of what causes a cricket ball to swing, many of them done in wind tunnels featuring myriad weather conditions. The result? It matters not one jot whether it is cloudy or clear or humid or dry. A cricket ball's tendency to swing has nothing to do with the weather.

Dr. Mehta, in a piece for a special physics edition of Teacher Plus magazine dated May-June 2015 titled 'Is cricket ball swing affected by weather?' writes 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. Well, the fact is that humid air is actually less dense than dry air..."

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." Here is Dr Mehta again: "The air density is higher on a cold day compared to that on a hot day. However, the dependence is not very strong with the air density being only about 4% higher at 15 degree Celsius compared to that at 25 degree Celsius. This means that a ball which swings about 2 feet at 25 degree Celsius will deviate about another inch at 15 degree Celsius. This is obviously not enough to explain what is observed on a cricket ground..."

The fact that dry air is denser should have been more than enough to debunk the idea that humid air aids swing. But that has not been the case. Like the flat earthers, many of us continue to spout erroneous ideas even though there is empirical data widely available that says otherwise. There is, admittedly, some mystery concerning the rudiments of swing bowling, but we should at least believe in science.

© Cricbuzz

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