Physics and Football: How Denver's Altitude Affects Field Goals

It's a fine afternoon in the Mile High City. Behind quarterback Peyton Manning's explosive offense, the Denver Broncos have amassed a 10-2 record. Today they're hosting the Tennessee Titans, a squad that's lost three of its past four games.

The Titans have put up a good fight over the first half-hour of gameplay. Three seconds before halftime, the score is Tennessee 21, Denver 17. Enter Broncos kicker Matt Prater. Trotting out to the Denver 46-yard line, he readies himself for the play of his life. A mighty kick sends the ball soaring end-over-end across the field as a nervous crowd holds its breath.

And then the place erupts. With ease, the ball sails through the yellow crossbar in Tennessee's endzone. It's the longest completed field goal in NFL history, a perfectly made 64-yard (58.5-meter) drill. Perhaps emboldened by Prater's heroics, the Broncos go on to crush the Titans in the second half, thus clinching a playoff berth.

Elevated Play

The game we've just described took place on Dec. 8, 2013. Five years later, Prater's 64-yarder still holds the all-time distance record. Although his accomplishment has never been bested, jaw-dropping football kicks are nothing new in the Rocky Mountains.

Three of the five longest field goals that the NFL has ever seen were made in Denver's Mile High Stadium. Broncos great Jason Elam nailed a 63-yarder (57.6-meter) there in 1998, a feat that was matched by Sebastian Janikowski when his Oakland Raiders came to town 13 years later.

But to hear some sports fans tell it, those three kicks should have asterisks attached. The official elevation of Colorado's capital is exactly 1 mile (1,609 meters) above sea level. No other NFL city sits anywhere close to that altitude; the runner-up is Glendale, Arizona, which looms a little over 1,000 feet (304 meters) above sea level.

Denver's elevation affects the sporting events up there. When a football is kicked at a Broncos home game, it's apt to cover more distance than it would in lower elevations like San Diego. This doesn't just affect three-point field goals; kickoffs tend to go farther as well.

For his book "Football Physics, the Science of the Game," University of Nebraska professor Timothy Gay ran the numbers on eight different teams from cities that (basically) sit at sea level — like the Miami Dolphins and New England Patriots — that played at least one road game in Denver during the 2001 or 2002 seasons.

He found that in those two years, the visiting kickers from low-elevation towns enjoyed some great numbers when they went to Denver. Up in Colorado, their kickoffs traveled 70.1 yards (64 meters) on average. Back in their respective home fields, that average kickoff distance dropped to 62.8 yards (57.4 meters).

Low Pressure, High Performance?

To understand those crazy numbers, we'll need to talk about air density. Pretend you've got a jet pack. If you were to take off at sea level and travel through Earth's atmosphere in a straight vertical line, the density of the air around you would get lower as your altitude increased. This is due to a universal law: As the distance between two objects grows, the gravitational pull that they exert on each other lessens.

Air molecules are not exempt. The pull of Earth's gravity is more strongly felt by those that are closer to the planet's center. At or below sea level, gravitational attraction packs the molecules tightly together. And the weight of all the molecules sitting higher up in the atmosphere really bears down on the ones occupying low elevations. In consequence, the air itself grows denser.

Way up in the Mile High City, the air's only about 82 percent as dense as it is at sea level. A ball kicked skyward in Denver will therefore encounter fewer air molecules than it would in Miami. That's important to note because air molecules create drag.

Drag is a force that pushes against solid bodies as they travel through fluids or gasses. A punted or kicked football will run headlong into a steady barrage of air molecules. Their combined drag will slow it down, sometimes dramatically. But remember, in low density air, molecules are fewer and farther between. Therefore, footballs can — and often do — encounter less drag in Denver.

Yet kicking on the Broncos' home turf won't guarantee success for kickers or punters. Altitude reduces air density (and by extension, drag), but cold weather increases it. And boy, can Colorado get chilly.

A 2011 survey of NFL statistical records found that in outdoor games played at temperatures of 39.2 degrees Fahrenheit (4 degrees Celsius) or lower, field goal accuracy drops by 1.7 percent, while the average punt length is about 1 yard (0.91 meters) shorter than normal. (These findings hold true throughout the league.)

So it's to Matt Prater's credit that his record-breaking field goal split the uprights from 64 yards (58.5 meters) out even though Denver's temperature had fallen to 14 degrees Fahrenheit (-10 degrees Celsius) at the time.

Whatever the weather, kicking specialists need to be on guard against complacency. Denver's reputation as the mecca of ultra-long field goals is well-established across the league. According to Patriots great Stephen Gostkowski, that Mile High mystique can trick visiting kickers into overestimating their abilities.

When in doubt, always "air" on the side of caution.