BS: Swinging delivery under cloud

Subject: BS: Swinging delivery under cloud
From: Penny S.
Date: 31 Jul 11 - 04:52 PM

I've just been watching the show "The Great British Weather" in which Freddie Flintoff the cricketer explained how cricketers believe that it is easier for bowlers to swing the ball when the weather is overcast, though there is no scientific evidence for this.

Is there any evidence from pitchers in baseball for a similar effect? The cricket swing occurs in the air, before the bounce, so would be similar to a baseball delivery. I remember an article in Scientific American about curve balls, but can't remember the weather beig cited.

Penny

Subject: RE: BS: Swinging delivery under cloud
From: gnu
Date: 31 Jul 11 - 07:13 PM

Easier to see the ball and any spin when it's cloudy?

Subject: RE: BS: Swinging delivery under cloud
From: Jim Dixon
Date: 31 Jul 11 - 07:21 PM

I don't follow baseball enough to know about this one, but I know this much about human nature:

In any situation where nobody fully understands the factors that determine success or failure—if nobody really knows why players have some good days and some bad days—people will invent superstitious explanations.

Subject: RE: BS: Swinging delivery under cloud
From: Micca
Date: 31 Jul 11 - 10:22 PM

Penny, the effects of weather is mentioned here

Subject: RE: BS: Swinging delivery under cloud
From: GUEST,Jon
Date: 01 Aug 11 - 04:02 AM

Fwiw, wikipedia says:

All other things being equal, cold and humid weather enhances swing, due to the lift force increasing with the density of the air. Colder air is more dense than warm air. The humidity is a measure of the water content in the air, and although water vapour does not increase the mean density of the air since water molecules weigh less than nitrogen or oxygen molecules, tiny suspended droplets of condensed liquid water will certainly do so since water is a fluid one-thousand times more dense than air.

Otoh, I have also heard it said that there is no scientific explanation so I'm unsure as to whether this is a generally accepted theory.

With this one I would doubt Jim's "people will invent superstitious explanations" though.

Subject: RE: BS: Swinging delivery under cloud
From: Musket
Date: 01 Aug 11 - 04:59 AM

In cricket, the ball trajectory has a more parabolic profile than in baseball and takes longer to reach target, especially with spin bowlers and slower seam bowlers.

I would take it on the chin there has been no scientific research into this, but would offer up the suggestion that simple physics dictates that the friction is different, hence the power behind the throw and the opposing gravitational resistance (taken as a constant relationship?) is affected by a variable, (air friction to give it a title) and so may be different, all other aspects remaining unchanged.

But comparing to baseball, the trajectory is, as I said, so different with cricket that if Freddie Flintoff is right, (and he is in an excellent position to relate experience) it still does not mean the same would apply with baseball.

I have always accepted that you can get the ball swinging better on overcast humid days, and it appears to be an observable reality. A bit surprised this has not been a viable research topic.

Subject: RE: BS: Swinging delivery under cloud
From: GUEST
Date: 01 Aug 11 - 05:04 AM

Swing in a cricket ball is also helped by polishing one side of the ball and roughing up the opposite side. Something to do with friction as the ball moves through the air.

Subject: RE: BS: Swinging delivery under cloud
From: Richard Bridge
Date: 01 Aug 11 - 05:17 AM

The conventional wisdom seems to be different between swing bowling and a slice service in tennis. This makes me suspicious.

Subject: RE: BS: Swinging delivery under cloud
From: GUEST,Jon
Date: 01 Aug 11 - 05:18 AM

Oh gnu,

Easier to see the ball and any spin when it's cloudy?

We are talking about swing. That is the path of the ball curving to the left or right in the air.

Subject: RE: BS: Swinging delivery under cloud
From: Musket
Date: 01 Aug 11 - 06:40 AM

Certainly roughing up one side and smoothing the other has an effect, as this makes it a less concentric mass point source.

The issue I suppose is determining whether or not this has an observable relationship with the air friction. In itself, perhaps not enough to notice, but perhaps enough to set off an eccentricity of movement that gathers pace as the moment of the force changes. Although if this were the case, it would be enough for a change of pace in the bowler's arm movement to increase or decrease spin to the same amount.

It is, in my opinion, (for what it is worth), difficult to state that all bowlers are capable of getting to the point where you need just that little bit extra air density increase to accentuate the effect of the eccentricity of the ball. I can't see that somehow. People are different enough so that surely, many could get it swinging as well on a sunny day and others need more than a cloudy day, yet ever all, most at the professional level get it swinging, hence there must be another variable at play I am not thinking of?

Sorry, getting a bit fascinated about this and have already looked up a few textbook references on bullet trajectory, as this is about as close a comparison I can think of, and there is a wealth of information out there on that topic.

Just out of interest, as I don't know. Do you shine and rough a baseball?

Subject: RE: BS: Swinging delivery under cloud
From: A Wandering Minstrel
Date: 01 Aug 11 - 08:19 AM

Atmopheric pressure is certainly a factor in trajectory. As an archer I notice that arrows fly lower on overcast days. In my playing days I always got more turn when spin bowling under grey skies.

Subject: RE: BS: Swinging delivery under cloud
From: Musket
Date: 01 Aug 11 - 08:35 AM

Ah! Wandering minstrel. Thanks for that. An arrow is designed to be concentric but manufacturing tolerance may not be to the nth degree.

Would you say that the effect is more prominent with some arrows rather than others? I am trying to understand whether the atmospheric variable is a large or small influence in general when it comes to objects powered by inertia (initial force, now just affected by friction / gravity.)

Ruddy thread.. I have work to get on with and have spent all day thinking about this bugger.....

Subject: RE: BS: Swinging delivery under cloud
From: Penny S.
Date: 01 Aug 11 - 04:05 PM

The program did include work done by a NASA scientist over a number of years, using a wind tunnel. (He was Indian, which could explain the interest.) He had found no effect. The cricketers remained convinced that there was one.

I wonder if it's not the ball at all, but the grass affecting the bowler's movement.

Penny

Subject: RE: BS: Swinging delivery under cloud
From: GUEST,Jon
Date: 01 Aug 11 - 04:31 PM

The behaviour changes as the ball wears Penny. Eventually the ball can start to reverse swing.

Subject: RE: BS: Swinging delivery under cloud
From: Musket
Date: 02 Aug 11 - 10:41 AM

The camera too shows there is one. Slow motion camera means every cricket fan watching it on Murdochvision can see when the ball starts to swing.

A ball that wears loses shape and becomes less concentric, hence accentuating whatever effect there is. We can see that it happens, hence the only thing missing is an empirical formula for predicting it. As I said earlier, there are ordnance calculations that take air humidity into account for bullet trajectory, but they are based on the premise that a bullet hasn't been roughed and smoothed.....

Subject: RE: BS: Swinging delivery under cloud
From: GUEST,Jon
Date: 02 Aug 11 - 11:14 AM

A short clip of Waqar Younis bowling.

---
btw I wonder what conditions accounted for this bowling

Subject: RE: BS: Swinging delivery under cloud
From: Musket
Date: 02 Aug 11 - 11:35 AM

The conditions started when his parents must have realised they had a genius for a son...

Subject: RE: BS: Swinging delivery under cloud
From: A Wandering Minstrel
Date: 02 Aug 11 - 11:50 AM

Ian, no it seems to be about the same for most arrows. It is something to do with lift generation being damped by heavier pressures. It might equally have a lateral effect in nonlinear objects such as a seamed cricket ball.