Air Density @ Sea Level vs. Air Density @ 5,280 feet (Meteorology vs. Football)

[Hannah.Taylor]

So,

A few weeks ago, Matt Prater kicked a 64 yard field goal in Denver against the Titans. Obviously, Denver is 5,280 feet above sea level.

http://www.nfl.com/news/story/0ap20...-prater-breaks-fieldgoal-record-with-64yarder
Watch video >

The Broncos first became a team in 1960.
They played 14 regular season games from 1960-1977.
7 games each season were played at home in the regular season, for a total of 126 regular season home games.

in 1978 the NFL went to a 16 game format. Meaning all teams played 8 home games and 8 away games.

From 1978-2013
The Broncos played 8 regular home games each season for a total of 280 home games.

Grand total of 406 regular season home games from 1960-2013. For the sake of this argument, this won't include post-season play, so no playoff games included.


So, lately I hear a lot of fans saying, the record isn't valid because Prater did it in Denver where the air is thinner and that gives him an advantage over other kickers.

in 1970, Tom Dempsey kicked a then NFL record 63 yard FG in New Orleans. However, Tom Dempsey had a foot with a birth defect, and he did it at/below sea level.

Dempsey also was a straight-on kicker, whereas Matt Prater is a soccer style kicker. Prater doesn't have any birth defects on his feet or toes, so he wears a normal/traditional style of football cleat (like seen on Dempsey's non-kicking/left foot).

Now here is an article that lists everyone who attempted to break the record.
http://www.nfl.com/news/story/0ap20...ed-tries-to-break-the-63yard-fieldgoal-record

This is an article that was posted shortly after Matt Prater's 59 YD FG to take the Bears to overtime in 2011 that talks about if kicking field goals in Denver is easier?
http://www.wired.com/wiredscience/2011/12/are-field-goals-easier-in-denver/

Only Sebastian Janikowski and Jason Elam have been able to tie the record. David Akers also tied the record but the kick was not in Denver, the kick was in Green Bay. in fact, 3 of the 5 kicks at 63 or 64 yards have been in Denver.

The original 63 yard FG record was by Tom Dempsey in New Orleans
http://www.youtube.com/watch?v=zrxTjgFYoU8

Now, according to this article and Dempsey's recollection, the weather was cool and humid on November 8th, 1970 (perhaps one of you weather geniuses can find the weather recordings for that day). Game was outdoors at Tulane Stadium.
http://sports.espn.go.com/nfl/columns/story?id=5648473

in the comment on the Failed Attempts to Break the Record, I saw some comments here

Cold weather increases relative humidity which increases air density which negates the effect of lower air density at high altitude. Therefore kick is legit. Physics ftw

and then there is a BUNCH of arguing and bickering back and forth.

so, since you weather guru's are all knowledgeable and stuff, I figured I'd ask you guys to dig through this and present the truth.


Question #1: So, if people are saying the kick is easier in Denver, and Denver has played 406 regular season homes games in Mile High and Sports Authority Field @ Mile High, then by the same logic that the kick is in fact "easier" because the air is thinner, then why is it in 406 games, no other kicker has been able to "break" the record?

December 8th, 2013
Prater's kick came at 5,280 feet above sea level
Temperature was 6ºF at the time of the kick (I was there at the game so I know how cold it was)
The ball was also cold and like kicking a brick or a lead weight at that temperature
Barometric Pressure was 29.95" Hg


November 8th, 1970
Dempsey's kick came on a "cool" day in New Orleans at sea level (or close to it) but a humid day.
No idea what the temp was.
Dempsey had a defective foot with a cube/block style shoe on with cloth stuffed in the front of it.


Question #2: Would the relative humidity in Denver on December 8th, 2013 and the colder temperatures increase the density of the air, therefore negating the effects of the thinner air on the ball?


Question #3: If Dempsey's kick in NOLA was so great, why did he never shatter his own record in Denver following that kick?

 

[Bob Schafer]

My goodness, Hannah, you put a lot of time and effort into this post. I can't pretend to be a scientist who is able to conjure and calculate the equations to solve your questions, but I do think there are some common-sense answers that have been overlooked. I did not look at any of the vids/links you posted, not because I am uninterested, but because I am tired. I drove for 13 hours today.

(Question) 1: Because Dempsey's feat was, in fact, that extraordinary. I mean, he accomplished that many years before Jason Elam was even able to tie his record, and Jason had two advantages in his favor. Big advantages, and I say that as a long time Broncos fan. Jason had the thin air of Mile-High, plus he had years of sports/physio technology behind him that was garnered in the intervening years.

2: Humidity makes air thinner. Think about it. Water is H2O. Hydrogen molecules have a molecular weight of 1, and each Oxygen molecule has a molecular weight of 16, so a water molecule has a molecular weight of 18. By contrast, each N2 molecule has a molecular weight of 28, and each O2 molecule is 32, so H2O thins it out (N2 and O2 are the majority of the air). The real key, though, is that the air is so much thinner at 5280 feet that the humidity is relatively immaterial. 100% humidity, 0% humidity, either way it makes little difference in the big picture when you're talking about sea level vs 5280. Errr, I should say it this way: 5280 with 0% humidity is still going to be wayyyy thinner than sea level with fog. I don't have any data to back that up, but I'm SURE that's true.

3: It takes a very rare set of circumstances to create a scenario whereby a team even gets into a situation where they are even attempting a record-setting field goal. It's very very unlikely that Dempsey ever got into that scenario while in Denver.

I just want to add one more thing. I don't believe that Dempsey's birth defect gave him any significant advantage. Other than to possibly give him a slight accuracy advantage, that defect would have given him no extra power that would have been transferred into the ball. One more thing, v.2: I saw Elam kick field goals in pre-game warmup that would have easily been good from 73 yards.

 

[Hannah.Taylor]

nice job Bob.

I'll throw this in as I just found it.

http://www.nhregister.com/sports/20...-praters-nfl-record-boot-is-a-thing-of-beauty

The Denver part of that equation will draw scrutiny. Elam’s and Janikowski’s 63-yarders also were kicked at the city’s altitude of 5,183 feet above sea level. “64 yds minus 20% discount for elevation equals yawn,” one of my Twitter followers wrote. The 20 percent refers to this: Air density decreases by about 20 percent for every mile of elevation. The less dense the air, the less drag on an object, the farther the object flies. But a 20 percent drop in density doesn’t mean kicks travel 20 percent farther. In his book The Physics of Football, Timothy Gay examined kickoffs in Denver and in eight sea-level stadiums in the 2001 and 2002 seasons. The kickoffs in Denver traveled about seven yards farther, or an average gain of about 10 percent. But, he said, the effect of altitude is less pronounced for field goals, which don’t sail as far as kickoffs and, for long ones, have flatter trajectories than kickoffs or punts. “I don’t think altitude is a super big effect” on field goals, Gay once told me.


Whatever the impact of Prater’s altitude boost yesterday, it was certainly mitigated by the weather. Temperature affects drag, regardless of altitude. “The ball will go farther in warm air at a given barometric pressure than it will in colder air at the same pressure,” Gay writes. The temperature at Sports Authority Field at the time of Prater’s 64-yarder was 14 degrees. “It’s a lot worse,” Prater said after the game about kicking in the cold. “But by that that time my foot was numb so I couldn’t really tell.”

 

[MClarkson]

Neglecting humidity, which is a secondary effect(even for a dolphins home game in September):

Density=Pressure/(R*Temp), where R=287.

Thus for Denver(~840mb) at the time of the game:
Density=84000/287/260=1.13

And for a typical sea level game:
Density=101000/287/285=1.24

The Denver air was ~10% less dense for that kick than a typical sea level game. Even Miami on a 30/23 Temp/Dewpoint day has a density of about 1.16.

 

[Jeff Duda]

I think there are a number of factors that interact to result in a record field goal kick. Bob and MClarkson already covered the science and some other aspects.

Air drag is proportional to air density (or maybe the sqrt of it...not sure for a football), so the reduced density in Denver results in less air drag on flying footballs. Wind also has a lot to do with it. Even with the same air density, there can be a dramatic difference in the effective maximum field goal distance caused by wind direction and speed (check out this video for a humorous example of how bad it can get: http://www.youtube.com/watch?v=ZIvQSXRQJtM). I don't know what the wind conditions were like at Invesco Field that day, but if Prater was kicking towards the south end zone with even a 5 mph north wind, that could add a few yards to any kicker's maximum range. All stadiums interact with the large-scale wind differently. Some stadiums allow more wind to get down towards field level, whereas others block it more.

Another factor, like Bob mentioned, is teams making a decision to kick such a long field goal. It is indeed rare for a team to decide to attempt a > 60 yd field goal because a miss will give the other team the ball on the wrong side of the field, a move most would consider foolhardy. Coaches get fired and kickers get traded or released for less nowadays, so there is a lot of pressure not to screw up in the special teams game. About the only time you'll ever see such field goals even attempted is at the end of a half when time is about to run out and it really doesn't matter if you miss. I believe that was the situation when Elam tied the record back in 1998 (+/- a few years...I can't remember the exact year). It was the situation with Prater here, too.

I think a final factor is the individual player - their psyche and physical build. I don't know how athletic or how strong of legs these kickers have. The small muscles around the hip and knee also probably play a role in how far they can kick. Even the strongest legged kicker can fail to make kicks from 30 yards if their head is messed up. Denver has this mystique as being the place to kick long field goals. This probably gets in the head of many kickers attempting long kicks away from Denver ("ohh...I can't make this kick...I'm not in Denver!").

By the way, it is possible for other kickers to make really long kicks at other locations. The Ravens' Justin Tucker kicked a 61-yarder in Detroit this past Monday night to beat the Lions. In the post-game interview he said he didn't feel like he got all of it. So there's that aspect, too, of getting the "sweet spot" of the ball on some of these kicks.

 

[Hannah.Taylor]

Prater's kick was to the north end zone, had a very slight wind, but not directly to his back, more like a diagonal.

 

[Mike Johnston]

Regarding your question #3, remember that Dempsey played most his career in the NFC, while Denver was an AFC team. The way the inter-conference schedules are set up, any given team played a given team from the other conference about once every 3 or 4 years. Moreover, they would rotate between which team was visiting and home teams. So, during his NFL/NFC career from 1969-1976, chances are Dempsey played in Denver only once, maybe twice. Then, he might have played there 1 or 2 times during the final 3 years of his career in the AFC, as the teams he played for were in different divisions from the AFC West Broncos. Add to this the aforementioned rare circumstances in which an extremely long field goal is even attempted, it's doubtful he even had a record attempt in Denver.

Whether his handicap and squared off shoe was an advantage or not has been somewhat controversial.

Probably the most famous sporting record set "at altitude" was Bob Beamon's long jump of 29 ft. 2 1/2 inches, which broke the previous record by almost 2 feet. This was set at the 1968 summer Olympics at Mexico City and the record stood for a remarkable 23 years.

The only modification of sports records for atmospheric conditions I am aware of are when certain sprint and jumping events are "wind aided."

P.S. You mentioned the Denver team started in 1960. Do you remember those ugly yellow and brown uniforms they wore back then, with those ridiculous vertical stripes on their socks? Bronco fans actually gathered and burned those uniforms a few years later.

 

[James Gustina]

I think air drag is directly proportional if memory serves me correctly, but don't quote me on that. This is just a personal observation but soccer-style kickers seem to have a better time of it without the aid of the environment (e.g. the lower air density in Denver as opposed to, say, Tampa Bay). If you've ever watched a soccer game, the keepers are able to absolutely blast the ball up the pitch just because of the style they use. Regardless of where Prater did it, his feat is pretty extraordinary in my book. I am a bit skeptical on the effects of the birth defect on Dempsey's kicking ability though. The shape of the cleat wouldn't be as important I don't think when it comes to hitting the sweetspot on an oblong shape, mainly because you can get more force per area on the ball with a square shaped cleat like he has above. I never played a down of football so I wouldn't know, but I know the shape of the cleat doesn't make a difference for a soccer ball.

 

[Hannah.Taylor]

2: Humidity makes air thinner. Think about it. Water is H2O. Hydrogen molecules have a molecular weight of 1, and each Oxygen molecule has a molecular weight of 16, so a water molecule has a molecular weight of 18. By contrast, each N2 molecule has a molecular weight of 28, and each O2 molecule is 32, so H2O thins it out (N2 and O2 are the majority of the air). The real key, though, is that the air is so much thinner at 5280 feet that the humidity is relatively immaterial. 100% humidity, 0% humidity, either way it makes little difference in the big picture when you're talking about sea level vs 5280. Errr, I should say it this way: 5280 with 0% humidity is still going to be wayyyy thinner than sea level with fog. I don't have any data to back that up, but I'm SURE that's true.

Bob isnt there a difference between humidity and relative humidity?

also see the link and post where I quoted from the nhregister.com link.

humidity itself might not reduce the air drag coefficient but wouldnt the temperature reduce it as stated in the link?

Whether his handicap and squared off shoe was an advantage or not has been somewhat controversial.

P.S. You mentioned the Denver team started in 1960. Do you remember those ugly yellow and brown uniforms they wore back then, with those ridiculous vertical stripes on their socks? Bronco fans actually gathered and burned those uniforms a few years later.

ugh i remember those uniforms...hideous!

well...i would think a squared off cleat like Dempseys would give you a bigger area of impact to power ratio on the surface of the football as opposed to a smaller rounded cleat.

in summation, Dempseys kicking foot and squared off cleat could hit the ball with more margin for error than Praters rounded toe which would require less margin for error to hit that sweet spot.