# Cold weather does indeed reduce ball pressure

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I’ve dusted off today a long-lost engineering degree from what seems like five lifetimes ago to explain how air pressure drops when the temperature does.

The concept is known as the ideal gas law.  PV equals nRT.  The “P” is pressure.  The “T” is temperature.  If the “V” (volume) the “n” (amount of gas, in “moles”) and the “R” (the “ideal gas constant,” which is sort of like pi) remain the same, a drop in temperature necessarily results in a drop in pressure.

The folks at SportsScience addressed this issue in 2010.  A ball exposed to 10-degree temperatures for an hour, the pressure drops from 13.5 PSI to 11 PSI.

Of course, that doesn’t fully account for a drop from 12.5 PSI to 10.5 PSI in 51-degree weather for 90 minutes or so.  But it proves that, when it’s cold, the pressure inside a football drops.

In this specific situation, it could be that some pressure was removed from the balls, and that the 51-degree temperature did the rest.  Regardless, when the mercury drops, footballs naturally deflate, at least a little.

## 139 responses to “Cold weather does indeed reduce ball pressure”

1. wydok says:

Assuming 68 degree room temperature to 51 degree playing temperature, you are looking at a decrease of .4psi.

2. As a chemist, I thoroughly enjoy freshman general chemistry being taught on PFT.

3. commenter says:

Not by two pounds, ladies and gents.

4. What about when they’re subjected to the bodily forces of football players acting on it and interacting with it (in addition to the temperature drop)? I don’t know. I’m just asking…

5. any idiot should know this…..

hence why some tires loose air pressure when the tempt drops soo many °

6. Don Shula was spot on.

7. I’m starting to wonder if the Patriots inflate the balls at a high temperature knowing that the air pressure will drop.
That would be a classic example of the Patriots knowing the rulebook and not breaking the rule, since they wouldn’t do anything to the ball after the official inspection, and they would be following the letter of the law.

8. Also, when the temp is hot the pressure will go up and increase the the circumference. Which really only helps the kicker.
But also has the temp is lower and will decrease pressure, the ball is easier to grip but a cold ball weights more.

9. sort of like pi multiplied bt ten to the 23rd power.

10. juice08 says:

11. What does this article have to do with anything? As stated, the temperature was in the 50s. That means that any natural deflation would be minimal. Also, wouldn’t it affect both sets of balls? No, someone on New England’s side is guilty. The question is, “Will anyone ever admit it?”

12. hairpie2 says:

Haters aren’t gonna like this….

13. > Assuming 68 degree room temperature to 51 degree playing temperature, you are looking at a decrease of .4psi.

The temperature dropped 20 degrees during the game, which started just after sunset.

14. it was not even cold on Sunday.. It was raining not snowing

15. RomoIsGod says:

Common sense tells you that cold weather reduces PSI, just look at your car tires in the winter. That being said, 51 degrees is not cold and could not impact the PSI of a football that much, if at all. Stop trying to make excuses, the Patriots cheated.

Now I don’t get the thumbs down for simply stating the truth. I’m not debating how good the Patriots are, just that they cheat. I compare them to Barry Bonds. They’d do just fine without cheating yet they still do.

16. commenter says:

It wasn’t even cold in Foxboro.

17. Volume being constant, (along with n and R) the change in pressure is proportional to the change in temp, so P2=P1(T2/T1). A 12.5 psi ball at 70F would be roughly 8.9 psi at 50f. Will the league replicate the pre-game process and conditions? I suspect the problem exists in the very cold games as well, (Ravens-Pats) but the ball is so cold the outside is stiff and hard, masking some of the pressure loss.

Would be interesting to see if the Colts’ balls had the same drop.

Personally, I think this is a bunch of Horse sh*t fabricated just to mess with the Pats as they enter the SB.

18. willycents says:

Soooooo. the one ball that was properly inflated violated the ideal gas law? I just read where all balls, Colts and Patriots, were checked at halftime, hence the delay at halftime, all the Colts balls and one Patriots ball were within specs, . Why were these other 13 balls not deflated?

19. cmr73 says:

I’m no physicist, but what if someone filled each football with hot air to the minimum 12.5 psi prior to inspection so the Patriots were in compliance. Is it safe to assume the PSI could drop to 10 or 10.5 considering the more extreme drop in air temperature from the time of inflation to game time?

20. questionableprovenance says:

Some things have to be clarified before applying the gas laws.

a) when the balls were measured as being deflated, where and when were the measurements taken? If they were taken after the suspect balls had been indoors, in a warm environment for some time, the pressure should have returned to “normal”. If they were measured outdoors, or immediately after being brought indoors, the cold would be a factor.

b) temperature is not the only factor. A wet ball [it was quite wet during the game] on a windy day would be far colder than a simple thermometer reading would indicate. This is where wind-chill factor comes from.

c) what was the temperature at halftime when the issue was noticed – the temperature was dropping during the late afternoon.

A drop from indoors 70 F to outdoors 51 F would lead to a pressure drop of about 4% or about 0.5 psi.

Lower air temperature, moisture, and wind would result in a far greater drop.

21. mattwalshvideo says:

But the Colts footballs were not deflated so this trial balloon just popped.

Nice try, Belicheat is a serial cheater, end of story.

22. neilpountney says:

Why are you using the top of the limit as your starting point??? How about the bottom limit!

23. vdogg says:

Is anyone else struggling to stay interested in this story? The Pats could have used a medicine ball and whooped the Colts on Sunday.

24. wydok says:

>The temperature dropped 20 degrees during the game, which started just after sunset.

If a 17 degree drop between inflation and game start causes a .4psi drop, another 20 degree drop between start and end of game wouldn’t cause a drop of another 1.6psi.

25. were the pressure gauges calibrated and certified?

26. weepingjebus says:

There’s a NY Times article from November 23, 2013 making the rounds. It’s all about how Eli Manning’s game footballs are “months in the making” and that they are subject to extensive soaking in water, warping, and conditioning before they get to the point where he will agree to use them in games — well in excess of the 45 minutes the refs permit teams to “officially” prep balls before the games start. That the NY Times pitches this as evidence of the brilliance of the Giants and their attention to detail shows you just how the Patriots are held to a completely different standard than any other team.

Remember, the Giants also were caught on tape engaging in synchronized cramping to slow down opposing offenses, and their starting QB gamed the draft system and daddy’s NFL connections to avoid playing on a team he thought would be awful. People admired this.

27. Spiking the ball 6 times a game in a 45-7 win could impact the PSI as well.

But the suggestion that it influenced a 45-7 game is ridiculous.

We of course don’t need science to explain how Aaron Rodgers was able to use over-inflated balls to give him a competitive advantage – he admitted it — which of course results in no articles, no fines etc.

28. sooo if this is the case, when playing in Lambeau the balls essentially become frisbees? lol. And has ANY other team had 11 of their 12 balls deflated by TWO full pounds per square inch? No.

29. rcali says:

Ha ha! Chea tri ots rise again! Now even multiple media people who they have in their back pockets coming up with excuses!

30. I have a question about all of this. Are there rules about exactly what “gas” is to be used for inflating footballs? Does it have to be “air”? Is that specified? Could a team use nitrogen (air is 78% nitrogen, or something in that ball park)? Or could they use something like argon, etc? And my next question is, how does temp affect psi of those other gasses?

For the sake of argument, lets say temp affects argon more than it affects air. What if the pats filled the balls to 11 psi with argon, and then 1.5 psi with air (12.5 psi) at a room temp of 72*. Lets also say they added hot air.

4 hours later (2 hours and 15 minutes before game, plus an hour and a half of game play) it wouldnt be absurd to think the psi of the balls had dropped significantly. Maybe even 2 lbs.

With that being said, it is reasonable to think the Pats complied with the rules, provided balls that were legal weights/measurements, and over the course of the game they fell out of spec without anyone doing anything illegal to the ball. Is that devious? Sure it is. Is it brilliant? Sure it is. Is it cheating and should it be punished? I dont know.

I also have a really hard time giving the Colts a free pass on this. There are “unwritten rules” and “gentlemans agreements” in all sports. From what I am reading, many view this as business as usual. “You dont mess with what I’m doing, I wont mess with what you are doing, wink wink”. Clearly the footballs are very important to the QB, and many QBs are very very very specific about what they want. Dont mess with what my QB wants, and I wont mess with what your QB wants. And the Colts, now appear to have decided that they may lose the battle (AFCCG), but they are going to win the war and tarnish the Pats/Belichick because they cant hang.

I want to know how many other teams out there, and their QBs, that are pissed about what the Colts did, because now they have to stop their manipulation of the balls

31. Are we taking away the Broncos titles in the late 90s also?!

32. jbl429 says:

It just so happens that the laws of physics only work this way on the Deflatriots sideline.

33. mrlaloosh says:

People, get a life. The Super Bowl is on February 1st. The day before Groundhogs Day. Some things just repeat themselves over and over.

34. If this is the counter-argument, everyone is ignoring the “magic” football that miraculously kept its pressure.

35. frotoon2 says:

Now explain why the 12th ball tested normal.

36. OK…but why then would the Patriots balls be deflated to an air pressure not similar to those of the Colts? If this argument had any relevance, both team’s balls would reflect the variance in temp-vs-air pressure ratios.

This article appears to be more of the Brady/Belichick “man love” reporting from the media. Why not say what is obvious to everyone that is not a fan of that team, they are cheaters! They have now been CAUGHT twice. Makes ya wonder how many times they get away with cheating between the times they get caught?!!

37. So the weather was the culprit, but it also decided to skip the 12th ball? Because science sometimes just gets lazy and doesn’t finish the job or something?

38. bobby2478 says:

Good point.

Now what are they going to do in order to ensure game balls maintain consistent temperature through the entire game, even in cold weather? Are they going to weigh and re-inspect them after each quarter, adjusting the air pressure in each ball so that they confine to the standards?

This just opens a can of worms if the ball has to always stay in constant temperature, when the study proves in cold weather a ball could start the game off properly inflated and subsequently lose 2+ PSI by the time the 4th quarter comes around making the balls no longer in compliance.

39. demons87 says:

Why doesn’t the league test the balls outside so the pressure is consistent regardless of temperature? So basically, the balls were consistent with the pressure of balls played in a game at roughly 0 degrees? Sounds like a non story to me.

40. That’s fine. But how do you explain that the only balls to lose air were being used by the Patriots?

41. The NFL is reassembling the Warren Commission as we speak to give a full report. I am sure this “magic ball” theory will be a part of it, right along side the newly found faulty pressure gauge that the Patriots will readily produce that was conveniently left behind by the un-named ball attendant who has mysteriously left town, whereabouts unknown.

42. theandy59 says:

@Kyatropic:
Some excellent points. That’s why in baseball you’ll almost never see a team challenge an opponents pitcher with regard to doctoring the ball cause they don’t want their own guy challenged.

43. If you’re starting with a fixed amount of gas (n) in the football inserted at a certain temperature (T) and filling a fixed volume (V), then the pressure (P) is going to change based upon two outside forces:

First, the temperature changed from inside the field house (say 70 degrees or so) to 51 at the start of the game to as low as 40-45 by halftime. That’s as much as a 35 degree swing.

Second, a cold front moved through. The outside pressure drops as this goes through.

These change in pressure is going to also have an impact out the pressure inside the ball.

I don’t blame the refs, Bill Belichick, Aaron Rodgers, or Brad Johnson with the TPMS light in my truck goes on (or off) or for when I have to spend \$1 for the crummy air machine at the gas station.

Why should this make any difference now if the Patriots filled their footballs with hot air to 12.5 psis and then let nature take its course?

44. Was the 2 pound reduction from 13.5 or 12.5?

45. joeconnorjr says:

This is why a crucial element of this investigation will be whether the League also tested the game balls that were in the custody of the Colts and, if so, whether they were properly inflated.

If the Colts’ game balls were properly inflated, this would tend to rule out weather as the cause of the under-inflated Patriot game balls. If the Colts’ game balls were not tested, however, it will be much more difficult for the League to establish that the Patriots purposely under-inflated their game balls to gain a competitive advantage.

Hopefully, the League officials who got involved with this issue last Sunday were on the ball (pun fully intended) and knew what they were doing. Otherwise, the League may have to sort through scientific formulas, scientific possibilities and other esoterica. We shall see.

46. What was the actual game temp? Did they measure them again at room temp?

47. Don’t let the facts get in the way of a good witch hunt! This is fueling the Pats!!

48. This is the best thing that could have happened to the pats.

They are coming out amped up with attitude.

49. mogogo1 says:

It also doesn’t explain why one of the balls was normal in pressure. It would have needed to have been over-inflated to start with if the temperature was the whole issue.

50. bobby2478 says:

By the time the NFL inspected each Pats ball, it was likely yesterday. If so, that means you need to clearly demonstrate chain of posession of each one of those balls from the time they were no longer in the Pats control to the time the investigation got them.

If you can’t prove who did (and who did not) come into contact with those balls, you don’t know who could have tampered with them letting pressure out. They didn’t do this during the game, it was well afterwards, and who knows who all had an opportunity to tamper with them.

You need to prove that the pressure discrepancy was a direct result of the Pats tampering with the balls, and that no one else had any opportunity to tamper with them.

Also, what temp were the balls when they were measured again? Were they exposed to cold air in the mean time? If so, the pressure could have dropped from the time the game was played to the time the investigation finally got around to measuring PSI.

51. OMG ppl, how many teams does this happen to? If this is the case, balls at Lambeau would be pancakes by the end. The patriots cheated, its pretty obvious. Nothing will be done, pat’s fans will keep thinking they are a “dynasty” after being caught with two major cheating scandals. The fact is- the only ppl that cheat are the ppl who expect to lose and cant win honestly.

52. wydok says:

>Was the 2 pound reduction from 13.5 or 12.5?

The balls were measured to be 10.5psi. So if they started at 13.5, it’s a 3psi reduction…

53. How many times are we going to let him get away with this?

He loses a draft pic? Big Deal..
He needs to go and patriots sanctioned for 4 years, NO PLAYOFFS.

54. So was it substantially warmer on the Colts sideline?

55. The league should find themselves about this. The balls, attendants and edge cases like these should be handled by league representative and not left to any club.

Also – what anyone is not looking at is the air in the football doesn’t remain inside forever! It does deflate or change pressure. Otherwise – we wont ever have to inflate a football or bike tire ever again!!

56. Pretty obvious
The pats started with properly inflated balls and those cheating colts started with over inflated balls

Super Bowl here we come

57. Someone then needs to explain to me, why then cart tires don’t need to have air adjusted daily. Even in the summer time, the temperature from early morning to mid afternoon is likely to be at least 20 degree difference. A tire containing 32 psi, would then drop in pressure 4 or more pounds based the assumption that a 12.5 psi football will drop 2 lbs with a temperature change of 20 degrees. Sorry but something is missing. Cars have warning lights for tire pressure, and yes it can happen that a tire can lose pressure on a cold day, but that is only likely when it is a much bigger drop temperature, and I usually only see about a 2 lb change from the normal 32 psi.

58. “oldtrix says:
Jan 21, 2015 11:21 AM
Volume being constant, (along with n and R) the change in pressure is proportional to the change in temp, so P2=P1(T2/T1). A 12.5 psi ball at 70F would be roughly 8.9 psi at 50f.”
——————————————————–

Units are wrong. You have to convert PSI to Pascal’s, and F to K.

12.5 PSI equals 86184 Pa
70F equals 294.3K
51F equals 283.7K

86184(283.7/294.3) = 83079 Pa = 12 PSI

59. A conspiracy theorists field day will become a great motivational tool for the Patriot’s come game day. Can’t wait!

60. RegisHawk says:

Lot of armchair GMs got their armchair law degrees today.

61. It was NOT 51 degrees by the time Brady threw the INT at 9:51 of the second quarter, and since the second measurements came later than that, the temperature fell even more. It was not even close to 51 degrees.

And to the people asking about the Colts’ balls, if they started at 13.5 PSI, theirs would be higher, but no one from the NFL has said their balls were tested too.

This is on the refs, not the Pats.

62. Wind Chill is only relevent with exposed skin. So, it wouldn’t cause the ball (or any other object) to be colder.
BTW, I wish the TV weathermen would stop telling us about the wind chill. What moron goes out in cold weather with lots of exposed skin? Just tell me the temperature, not this man-made concept of “wind chill”. Of course, they do it so the weather seems worse, which makes it more dramatic, which they believe will make their weather report more compelling.

63. Indoor-to-outdoor Temperature Variation. Significant differences between the conditions tire pressures are set (the warmth of an attached garage, heated garage or service shop) and in which the vehicle will be driven (winter’s subfreezing temperatures) requires inflating tires 1 psi higher than recommended on the placard for every 10° F difference in temperature between interior and exterior temperatures.

Also, add the moisture with the wind on the balls, that further reduces surface temperature. Evaporation cooling. Standout side in the cold dry, standout side in the cold wet, add wind. You are really cold.

THE SAME APPLIES TO FOOTBALLS

64. Did the NFL inspect the footballs at halftime on the Colts sideline? Compare the drop in pressure and move forward. If the pressure drop is inconsistent then it’s obvious some tampering took place otherwise call it a wrap. Or did the NFL fumbled another investigation and not check the Colts footballs????

65. truckinmack says:

Mr. Engineer, as a fun test, soak your foot in 72 degree water and notice how cold that feels, while 72 degree air is quite comfy.

Water conducts temperature more effectively than air. Run water cooled to 50 degrees over a football for 60 minutes and monitor it’s air pressure.

66. skocpol2015 says:

Mike, could you check the temperature trajectory for several hours before the game. I believe it was in thirties before rising to 51. One hope the league is asking when the balls were checked, at what room temperature, and when they went to the sidelines, what temp it was then. Also, did they do a control by checking Colts balls at half time?

It is not hard for me to imagine Pats having the balls at lowest possible pressure, 12.5′ and then their going below that. It is really hard to imagine a Pats staffer deliberately deflating 11 of 12.

Theda S.

Theda S.

67. The #1 question should be:
What is the average drop in air presure during every NFL football game?
If that average falls anywhere close to 2 lbs, then everyone needs to shut up and let it go.
This is the dumbest “scandal” i’ve ever seen.
brought up by Patriot haters and talked ad nauseam by every radio/tv/newspaper/internet/blogger for time filler.
#givemeafregginbreak

68. FinFan68 says:

cmr73 says:
Jan 21, 2015 11:23 AM
I’m no physicist, but what if someone filled each football with hot air to the minimum 12.5 psi prior to inspection so the Patriots were in compliance. Is it safe to assume the PSI could drop to 10 or 10.5 considering the more extreme drop in air temperature from the time of inflation to game time?
~~~~~~~~~
This is a point I have tried to make on other articles. I seriously doubt the balls were doctored during the game. I believe they were at the minimum allowable psi when initially tested and various conditions allowed the pressure to drop.

I suspect many teams fiddle with the numbers a bit pre-game and at least one team (Vikings?) said they put the balls in an oven which is exactly the type of effect you describe. This is a big deal for two simple reasons. It’s the Patriots and the Super Bowl is in 2 weeks.

69. Bringing the ball in to a warmer room to measure it would raise the pressure accordingly, no?

70. If this is so common then why hasnt it been talked about before? If it is common then the NFL would have made a statement that this is common and its over with. Im pretty sure the NFL has more of an idea of how a balls reacts in games than any of us do. And if the ball can drop THAT much in the second quarter, then by 4th quarter it would have dropped 4lbs of pressure and they would be playing with a flat ball. If balls last at Lambeau, then im sure a 90 min game in NE at 51 degrees wont deflate a ball that much.

71. spreth1 says:

I’m fascinated with how the same scientific data leads people to draw completely different conclusions when none of us know the “truth”.

This is like Science v. Religion revisited.

72. I think the whole “Story” is BS… in a 45 to 7 game.. Common man.. BUT the question by some is why not the Colts balls… MAYBE .. and this was never discussed. WHERE were the balls kept during the game

Or the Colts needed a “warm and dry ball” for Luck to have better feel it is possible it was kept covered on the heated benches.

If anyone watched the Youtube video references in the article on how less pressure affects performance of a football you realize less is worse…

We dont know.. and frankly with a blowout score like that it makes little to no difference on the outcome. Luck played badly with the Colts OWN balls.. and most of the Patriots points were in the second half AFTER the balls were checked and corrected.

For those that think I am a Pats fan.. think again…. I am and always will be a Philly native and Eagles fan.

73. zvikes says:
Jan 21, 2015 11:31 AM
So the weather was the culprit, but it also decided to skip the 12th ball? Because science sometimes just gets lazy and doesn’t finish the job or something?
**********************************
Under inflated balls help the QB grip the ball. Higher inflated balls benefit the kicker…Science isn’t lazy, the kicker needed a properly inflated ball.

That said, the Pats may or may not have doctored the balls before they realized they didn’t need to. If the refs checked at halftime then the second half should have been equal ground for both teams. As one poster stated, it was 28-0 in the second half and 17-7 in the first half. Looks to me that this whole discussion should be moot. The Pats won. Let’s move on.

74. Happens to the tires in our many trucks every winter. As soon as it turns cold all of the under-inflated alarms go off and the tires have to be inflated.

75. As a control group, did they also test the 12 Colt’s balls?

76. I’m not a pats fan, admittedly. But i dont agree with the whole “well the second half we beat them too” thing. You cheated and got a lead over them, which means their spirits were low and now they are playing from behind and making decisions they wouldnt make if they were up in the game. Start evenly and they finished the first half tied, then their strategy and spirits are completely different.

77. This just in: water is wet. Since we seem to be reporting on the fairly obvious.

78. dlk47823 says:

There’s one issue with this…..All Indy balls tested at the perfect weight, must have ben allot colder on the NE sideline.

79. gator2006 says:

Does not*

80. redsoxu571 says:

This lends itself to an interesting potential tactic: couldn’t teams store their balls pre-inspection in a somewhat heated area at the proper minimum pressure, hand them over for inspection, and then see the balls lose even more pressure due to the temperature change? Hmmmmmm. But don’t tell Belichick!

81. how long before the game are the balls filled ? are they inflated on the field or in a warm equipment room ?

82. jmac1013 says:

Why did the balls used by the colts not deflate? They were measured in spec.

As I posted in another story…once a cheater, always a cheater.

Makes me wonder in what other areas are the patriots cheating. Zero integrity.

83. weepingjebus says:

If balls lose inflation when they get spiked for touchdowns, that explains why none of the Colts balls were deflated.

84. PV=nRT only applies to 11 out of every 12 footballs. You learn that in freshman physics.

85. cometkazie says:

balsagna says: Jan 21, 2015 11:14 AM

As a chemist, I thoroughly enjoy freshman general chemistry being taught on PFT.
+-+-+

But this is physics. High school physics.

Signed: Another Chemist
+-+-+
madmax80 says: Jan 21, 2015 11:17 AM

sort of like pi multiplied bt ten to the 23rd power.
+-+-+

That would be close to Avogadro’s number, 6.2 x 10^23

You need to use absolute temperatures here to ratio. Absolute zero in F is -460, or there abouts, so the ratio of 70° and 50° is not 50/70=0.71, but
510/530=0.962, or a little less than 4%. 4% of 13.5psig is 0.54

Yes, gas laws apply to all gases within the ranges we are discussing.

I wonder how long a football holds its pressure?

I wonder how the refs check the pressure or if they just check the weights? 2 liters of nitrogen weigh about 2.5g at 32F and one atmosphere. Assuming the football is pressurized to 13psig, there would be about 4.5g, not much, about what a 25¢ piece weighs.

Checking the pressure will allow a bit of air to escape so you have that, too.

A lot more here than meets the eye.

86. Were the Colts footballs tested? If so and they were found to be fine then how does one try and use the cold weather as the excuse for this Patriots story?

87. start inflating all game balls with nitrogen. it doesn’t expand and contract like “normal air” does.

88. So this means the Bills actually WON 4 straight Super Bowls?

89. I live in New England and our weather was similar to what was going on in MA on Sunday. Indeed, once the sun set the temperature dropped quickly and the change was pretty large, 20-25 degrees by the time the game ended.

90. I think it’s time for ball warmers!! That sounds nice.

91. SeenThisB4 says:

I guess it was only cold on the Patriots side of the field.

92. thelastwordyaheard says:

the Patriots could’ve played with a greased pig & still stomped all over the pathetic Colts

93. PFT’s Most Censored says:
Jan 21, 2015 11:42 AM
He loses a draft pic? Big Deal..
He needs to go and patriots sanctioned for 4 years, NO PLAYOFFS.

agreed, and the vikings & bucs got caught this year. Also rodgers already admitted to doctoring balls also so ban him too and no playoffs for GB for 4 years also!

94. Say what you want. But I don’t always believe this Sports Science bull.

Units are wrong. You have to convert PSI to Pascal’s, and F to K.

12.5 PSI equals 86184 Pa
70F equals 294.3K
51F equals 283.7K

86184(283.7/294.3) = 83079 Pa = 12 PSI

Actually, you don’t need to convert Pascals. Using P1/T1 = P1/T2 just make sure P is in psi and T is in Rankine (add 460 to the Fahrenheit number).

Balls filled at 68 F (room temperature) to 12.5 psig would drop to 12.1 psig at 58 F

96. What about the special ball? 11 out of 12 were deflated. If you wanna blame it on weather then his did the magic ball stay inflated?

97. zen609 says:

This blog post kinda makes it sound the pressure change due to temperature variance is permanent, and that’s not true – it’s value changes with temperature. The pressure will be slightly lower (not 2 psi, though) due to the lower temperature on the field, but increases to it’s original value when the balls are warmed again.

If, in the investigation, the balls were checked at room temperature, and the pressure of these 11 balls was lower than spec, the field temp at game time isn’t the cause.

The other 13 balls (1 Pat ball, 12 Colt balls) were also on the field. If you would have tested the pressure of those balls on the field, they would have had a slightly lower pressure due to the lower temp, but when they warmed again to room temp, the pressure increased to it’s original room temp value.

The pressure of the 11 underinflated balls should be within spec at room temperature – the temperature on the field at game time doesn’t effect the pressure as measured at room temp days later.

98. Along with the Temperature drop, inside a warm locker room it could be more like 75 degrees then taken outside and been in 50 degree weather.

Also, what about the barometric pressure of the storm that was passing over, could that drop air pressure in a ball? I’m just curious…I have no favor in the argument.

Lastly…
If this had happened under another team/coach this probably would not be talked about but the Patriots under Belicheat has to cause some suspicions.

Thanks everybody!

99. Not only would all 12 be impacted the same, why weren’t the Colts 12 balls impacted the same

100. cobrala2 says:

Oh, so the footballs are in a controlled environment with a constant temperature of X and humidity level of Y and then at the precise moment of kickoff they’re all simultaneously exposed to the elements of the game?

IDK why you even mention 90 minutes.

So many freaking variables here with negligible oversight or monitoring… I can’t stand the Pats, I think they cheated with Spygate but this is a crock.

If someone puts a deflated ball on field pre-punt/fg/kickoff then I see cheating.

Otherwise, one word: WHATEVER

101. Dave Fouchey says:

I have to say I am loving the Mr. Wizard segment of PFT this afternoon. As for the difference in pressures between the Colts and the Pats an earlier article mentioned that the Colts chose to inflate their balls to the max and the Patriots to the minimum. Which given the number of variables in handling, temperature, usage, game time etc could account for a fair amount of difference. Also this article mentioned that BOTH the Colts and Pats balls were checked at halftime. It did NOT give the pressure readings from the Colts balls only that they remained in spec. And with all of that said does anyone REALLY think that 2 psi made that much difference in the butt whuppin New England put on Indianapolis?

102. The NFL should learn from NASCAR and use nitrogen to inflate the footballs. Nascar uses it because it doesn’t respond to temp changes as radically (i.e. a cold tire goes through a greater temp change than any football), and even a qtr lb off could make a good day suck. The NFL should use the nitrogen; let each team decide what psi they like (in rule specs), and then lock them up until game time.

103. xpensivewinos says:

So it was cold on only one sideline?

Now that’s some crazy New England weather…..

104. Someone mentioned wind chill factor which is very valid. Another mentioned why Colt’s balls didn’t exhibit this pressure drop which is also very valid. Any mention as to how the balls were stored? Maybe Colts have their balls under a tarp to keep them dry near the heaters while Pats balls were left exposed to the cold/rain/wind. I believe that in itself isn’t illegal, but it would definitely be attention to detail in stacking the deck that Pats would try to pull off.

105. Guys,
A couple of things you are doing is not correct. Yes, PV=nRT, that is Pressure times volume is equal to the number of moles times a constant times the temperature. Note the temperature is in elvin not Fahrenheit or Celsius. This will make a difference and its not a difference but an actual temperature. So with the equation solving for P and T we get P/T=nR/V. nR/V will be a constant in this case so P/T at measuring time is equal to p/t at game time or later (Lower case used only to differentiate time of measurement). so P/T=p/t or P*t/T=p. the balls were measured at say 68 degrees Fahrenheit is 293.15 kelvin. The ball is inflated to 12.5 psi. And lets say the temperature at game time is 51 degrees F is 283.70 K so the ball would be at 12.09 psi.
So let’s reverse engineer this to drop from 12.5 psi to 10.5 psi we get this: t= pT/P so t= 246.25 K or -16.42 Fahrenheit. It was not that cold.
So how hot must the ball have been to measure 10.5 psi if it was 31 degrees F so solve for T. You get T=Pt/p. 31 F=272.59 K. it works out to be 324.51 K or 124.45 F. pretty hot. How hot is a sauna?

106. This is why kicking FGs in 20 degree weather is so much more difficult. Balls should be inflated and measured at field temperature for all games.

107. cometkazie says:

drewser43 says: Jan 21, 2015 12:58 PM

start inflating all game balls with nitrogen. it doesn’t expand and contract like “normal air” does.
+-+-+

Not true.

The relationship is for all gases.

108. And then when they’re warmed up they return to their regular pressure.

109. “Is anyone else struggling to stay interested in this story? The Pats could have used a medicine ball and whooped the Colts on Sunday.”
======================================
And it still would have been against the rules. Whether they won or lost is immaterial. It’s how they played the game. No one cares if you won if there is the stigma of cheating. The Patriots should know this.

110. weepingjebus says:
Jan 21, 2015 11:25 AM
There’s a NY Times article from November 23, 2013 making the rounds. It’s all about how Eli Manning’s game footballs are “months in the making” and that they are subject to extensive soaking in water, warping, and conditioning before they get to the point where he will agree to use them in games — well in excess of the 45 minutes the refs permit teams to “officially” prep balls before the games start. That the NY Times pitches this as evidence of the brilliance of the Giants and their attention to detail shows you just how the Patriots are held to a completely different standard than any other team.

Remember, the Giants also were caught on tape engaging in synchronized cramping to slow down opposing offenses, and their starting QB gamed the draft system and daddy’s NFL connections to avoid playing on a team he thought would be awful. People admired this.
__________

The mandated “45 minutes to prep balls” is only in regards to the kicking balls (a/k/a K-balls; a/k/a the balls specifically meant for ST plays). 8 brand new balls are sealed in a special box by the manufacturer, are sent from the manufacturer directly to the Ref, and are opened 2 hours and 15 minutes before gametime. They’re specially marked by the Refs as K-balls to be exclusively for kicking, and teams may only prep them 45 minutes in advance of the game.

The cramping thing is certainly unsportsmanlike conduct.

I’ve never heard anyone “admire” Eli’s draft day hissy fit. In fact, I’ve seen his entitled, pissy attitude derided openly, or simply purposely ignored/averted (in the case of Giants fans that know they can’t condone the behavior, but prefer Eli as their QB, so want to remain in denial about how much of a whiny little brat he was being), but never “admired”. The only thing I’ve seen “admired” about that situation is the Chargers, despite everyone knowing they wanted Rivers, knew the Giants wanted Eli, and actually had the gumption to take Eli hostage and come away with Rivers, a 3rd rounder that year, and a 1st and 5th rounder the next year. That was one heck of a coup. But again, Giants and their fans may have been and may currently be happy that they got the QB they wanted, but I’ve never heard anyone admire Eli for his hissy fit.

111. To the people saying that spiking the ball after a TD would take air out of the ball: They had 12 balls and scored 6 TDs. Do the math.

112. Would be so amazing if it comes out the Colts ballboy went rogue messing with the balls trying to screw up the Patriots.

113. shawkfan51 says:

@mikefreemanNFL: Gerry Austin, longtime referee, says halftime Pats-Colts footballs brought in, checked at half. Colts footballs still legal. Pats were not.

114. ecppeaters says: Jan 21, 2015 11:46 AM

Someone then needs to explain to me, why then cart tires don’t need to have air adjusted daily. Even in the summer time, the temperature from early morning to mid afternoon is likely to be at least 20 degree difference. A tire containing 32 psi, would then drop in pressure 4 or more pounds based the assumption that a 12.5 psi football will drop 2 lbs with a temperature change of 20 degrees. Sorry but something is missing. Cars have warning lights for tire pressure, and yes it can happen that a tire can lose pressure on a cold day, but that is only likely when it is a much bigger drop temperature, and I usually only see about a 2 lb change from the normal 32 psi.

———————————————————-

TPMS usually alert when the pressure of one tire is x psi different than the average of the other three, not when all four tires lose pressure at a steady rate.

Also, do you routinely check the pressure of your tires several times throughout the day and add/remove air as necessary? Neither does anyone else.

115. tigerlilac says:

Finally, a climate denier (just a joke, don’t take offense) allows for scientific facts to be included in the discussion (a place I don’t believe in just froze over). Now, can we have some real scientists chime in (see today’s Boston.com). Also, maybe, just maybe, the NFL approved balls that were less than 12.5 psi and the combination of those two factors lead to the discrepancies noted by the NFL. Are you ready to concede that yet, Mike, so we can get back to talking football and the world class athletes that will play in the Super Bowl?

116. “Maybe Colts have their balls under a tarp to keep them dry near the heaters while Pats balls were left exposed to the cold/rain/wind. ”

This whole event is going to supply comedians for years :)!

117. misterpasta says:

Can any of you geniuses please explain to this high school graduate how the ball pressure dropped ONLY in the Patriots ball bag? Were the Colts holding their footballs on Bora Bora?

118. Once again, wind chill is a non-factor. No amount of wind can make an objects’ temperature go below the ambient temperature. The wind can cause an object (football) that has been brought outside to cool down to ambient quicker, due to more rapid heat loss, but it will not become colder than the ambient temperature. If it’s 30 degrees outside, than the coldest the football will become is 30 degrees, no matter the wind.
Wind chill is relevant for human flesh only. The wind causes exposed flesh to lose heat more quickly. We sense that as “more cold” but that’s because we’re alive and can “feel” it. It’s simply to quantify how much colder the air feels to exposed flesh in the wind compared to no wind. The footballs are not alive, thus can’t “feel” anything.
Weathermen need to be shot for ever bringing up wind chill. Who in their right mind goes outside unclothed when it’s very cold?
Don’t even get me started on the “hot water freezes first” myth. SMH…

119. cometkazie says:

juvat308-Evaporative cooling can cool objects below ambient.

120. Bora Bora is a plausible explanation.

121. Note to all who attempted to do the calculation, both Pressure and Temperature need to be in absolute terms. The 12.5 psi value quoted is in “gage” pressure, that is

P_gage = P_football – P_atmosphere = 12.5 psi

Atmospheric pressure is typically 14.7 psi, so the pressure inside the football at the minimum pressure is 27.2 psi. So the math for a change from 72F (22.2C) to 51F (10.6C) comes out to:

P_gage_cold = 27.2 psi *(10.6+273.15)K/(22.2+273.15)K – 14.7 psi = 11.4 psi

So 51F could cause about a 1.1 psi drop. If the temperature dropped to 41F, the pressure would be 10.9 psi, close to the 2 psi difference reported. If the temperature dropped to 32F, the pressure would be a full 2 psi below the 12.5 psi limit.

122. cometkazie says:

Excellent point, Dr. Curt. I rarely dealt in gauge pressure being a scientist and not an engineer.

That’s my excuse.

😉

123. ocgunslinger says:

I love the fascination here about the Patriots Cheating as if that is the reason they have been winning the past 12 years.

It’s time for the Patriots to admit they have been taking unfair advantage of the rest of the league….. they outsmart them from schemes, half tiem adjustments to well coached versatile players and have everyone so paranoid and so much into the cheating claims that meanwhile they are being outcoached, outsmarted and yes… outplayed. Billichick is brilliant. I wonder what will be the next cheating episode to distract (only happens when they win) allowing the Pats another mental advantage for the upcoming game.

124. smasonsmith says:

To dovetail onto what drcurt says…

If the balls were hot and within the legal range when they were measured pre game, they would have had farther to fall in temperature to reach ambient. That means greater pressure loss, since the change in temp is proportional to change in pressure.

125. I live 60 miles north of Foxboro and we were getting freezing rain. I would put the temperature of the ball not much higher than 32 F. Also barometric pressure was falling through the entire day. Average temperature of conditioned space is 70 degrees.
These balls are like gold , so reason says that before the game they were indoor. When tested at halftime did they take into account the original temperature? As for the 1 mystery ball. You have 12 balls in a bag, will they all be exposed or could one in the middle only be touching the other balls there for insulated from the rain temperature and only subject to air temperature changes?
I’m sure that they are well aware of this.
But cheating….then every time a team plays in Denver that team is cheating.

I see it like this , a great way to not have the year called the year which they commissioner endorsed beating your wife when you can have the year the patriots were caught cheating again. After it is a multi million dollar business 1st.

126. We all know Bill Belichik is a rule skater…so what if he had the temperature turned up like say to 80 degrees in the equip room where they were inflated to 12.5 psi and then go out to 50 degree weather…wouldn’t that knock off like 2 or 3 psi? He knows what impact room temp will have on the balls without touching them. By the end of the game the outdoor temp dropped even further.

127. chuckellis2015 says:

Yes dram931…80 degrees would hardly be unusual indoors in a closed heated room in the winter. The National Weather Service had the temperature in nearby Taunton at 44 degrees at 8:52 PM – halftime – so that would be a 36 degree drop from 80 degrees, would account for just over 1.5 psi drop

128. Dram931 & Chuckellis2015 Yes that might do it or even take it into the sauna for a bit. All of this could be done so that the Balls deflate with no ones help after they are measured by the officials.

129. This is so funny, so the Pats won by cheating in the second half. The Colts footballs did not change in the second half, but they did not score either. Tom Brady threw his only interception in the second half, when their footballs were under inflated. Ok we take away all scoring that the Patriots had in the second half and that is the final score. We have the same winner because, the Patriots did not just blow the Colts away on offense, their defense shut down the Colts offense that was going to score over 24 points easily with Luck at quarterback. All this is in the news and the NFL has done nothing because, who really cares about the pro bowl? The players get a free trip to Hawaii and do not play anywhere close to their potential because it’s just a bull crap game. The NFL wants its name out there till the Super Bowl. Plus the fine for tampering with the footballs in the rule book is \$25,000. So that is what the Patriots should pay. Not sure if that is per ball or per occurrence but that’s in the rule book. Like it or not!!!

130. I am a pats fan so I know i’m not an objective 3rd party. I dont know if the Patriots truely cheated or not, but wanted to bring one thing up. I am sorry if this has already been brought up, but I didnt want to read 600 posts. I am one that does think that the pressure dropped the psi. My understanding is that each team is allowed to pick their 12 game balls (to practice and scuff up). This also allows the team to determine where they want the pressure to be within the legal limits. So when people say why were the pats game balls underinflated and the colts were within limits; what if Andrew luck preferred the game ball at a higher psi, which in turn would keep it legal even when deflated? They said the pats put it at 12.5 which is legal and dropped 1 psi or 2. What if Luck just preferred it at 13.5 and it went down to 12.5 staying legal. Ive heard conflicting reports whether it was 1 psi or 2 Below limit. This is all just rediculous either way.

131. the text messages between the two NE clubhouse attendants clearly show that Brady instructed them to deflate the balls. come up with whatever theories you want, but that is the smoking gun.

132. I thought most visiting teams kept there balls warm for the qb to have a better grip . I thought that was the ball boys job . But a real qb like brady just grabbed em cold