Air Pressure and Golf Ball Distance

I've read a lot about the effects of cold and warm weather on the effects of golf ball distance, as well as elevation. Really elevation can correlate to air pressure since the higher the elevation, typically the lower the air pressure.

Yesterday I was playing a round of golf in the PNW (Vancouver specifically). Temperature was around 46F (8C) and of course humidity was around 90%. I did not know what the air pressure was at the time.

On the second hole, I'm lying 126 to the pin and I've got around 7 yards from pin to back of green. I hit a PW, which would normally travel 120 yards at 46F (summer distance is near 130). I walk to the green to discover I flew the green. My ball mark was on the very back; that's about 132 yards carry. I'm shocked, so I jump on the iPhone to look at the air pressure; it's 99.4Pa (994mb for you Americans). This is super low air pressure for the PNW and especially at sea level. Standard air pressure is 101.5Pa or 1015mb. The air pressure in the PNW is typically around 102Pa or 1020, slightly high air pressure. We all know we have to adjust for distance at sea level, unless you are playing in Florida, the temp offsets the air pressure I believe.

Hole 9, I have 136 to the pin and around 10 yards to the back. I take out a 9 iron and choke down 1/2 an inch and swing 3/4. I airmail the green. Drives were going around 270 (which is respectable in summer at sea level); the tour average at last years RBC Canadian Open (2011), was around 270. I was driving this distance in soft conditions and at 46F. Had it been summer, I would have been driving 300 all day, which I've never done at sea level.

I've read quite a bit that temperature has greater effect on ball distance than elevation. I'm not sure this is the case. I think whichever measure is more extreme, might be the more significant factor. If they are both at the extreme end, it could mean a 2 club difference.

My golf buddy's think its funny that I check the air pressure before a round. Most of the time it's irrelevant, but for those times when the air pressure is extremely abnormal, I know it's made a big difference; 5 yards could make the difference between birdie and boggie.

Quote:

Originally Posted by sacm3bill 

 

Lower pressure does make the ball travel farther. But higher humidity will do the same thing, due to the resulting decrease in air density. Probably a combination of those factors.

Humidity averages 90% in the winter months in Vancouver, this factor is constant.

Quote:

Originally Posted by iacas 

Colder air is denser. Humid air is less dense. The denser the air the shorter the ball goes and vice versa. The two factors interplay with each other, along with altitude (higher = less dense air).

 

So what's your question exactly?

Well that is the general principle; however, yesterday's cold air was not denser, the air pressure was 99.4 (994 or 29.35). I play at least 40 rounds of golf from Nov to Feb and can tell you that the air is typically a lot more dense. Not only am I at sea level, the air is cold in the Pacific Northwest. The air pressure is normally around 102 (1020, 30.62). I normally have to club up all winter. Yesterday the ball traveled as though I was playing in 75F weather, not 47F. So although cold air is typically more dense, it was not yesterday as a result of a low pressure system.

I don't have a question, just more of an observation. Days like yesterday don't happen often. Sometimes I experience the opposite, it may be 70F outside, but the barometric pressure is over 103, the ball flies as though I'm playing in the winter. I play as an amateur on the Vancouver Golf Tour (Like the Pepsi Tour). If I had a tourney yesterday and did not check the a barometric pressure, the 3 greens I airmailed would have resulted in 5 extra strokes.

Some parts of the U.S. and Canada have little variance in air pressure, others have wild swings, Alaska and South Carolina are examples. In much of the continent, it probably does not matter, but where there are wild swings (yesterday for example), it obviously can have a major impact; that is if you're stock PW usually lands within a 10 foot circle...

I've only lived in the PNW for 4 years, I've scratched my head on many shots until I started to correlate air pressure and ball flight.

Quote:

Originally Posted by David in FL 

There's an old saying..... When you hear hoofbeats, think horses, not zebras. In other words, look to the most likely cause, not an unlikely one.
Rather than considering the atmospheric pressure and humidity as the cause of your extra distance yesterday, is it possible that you were simply striking the ball well....?

So you're saying the barometric pressure is unlikely?

I'm a pretty good ball striker, but there's no way that a 105-107 mph driver swing speed nets 270 yards consistently at 47F in the Pacific Northwest. The PGA tour average at the 2011 RBC Canadian open (my neighborhood), was in the 270's, in summer. The only plausible explanation was the significant difference in Air Pressure from normal for this region of the golfing world...

http://www.madsci.org/posts/archives/2000-07/962413045.Ph.r.html

"Finally let's consider air pressure which has probably the biggest effect of the three. Simple stated, less air pressure means less aerodynamic drag (air resistance). Viscosity (drag through a fluid) is inversely proportional to air pressure (or density, really). Since the golf ball does not depend on air pressure (or density) for thrust (like a jet engine), it will fly farther. The effects of air pressure (density) are usually approximated as linear. This is not a great approximation all the time, but it pretty close. Therefore, a 10% drop in air pressure will turn a 240 yard drive into about 267 yards."

Quote:

Originally Posted by iacas 

 

You do realize that humidity plays a role in the density of the air, as I already said, right?

 

I believe a standard barometric pressure of about 30 assumes 20°C, 1.25 kg/m^3 and 20% humidity at sea level. So colder air is simply denser than warmer air all other things equal. You weren't at sea level, you weren't at 20% relative humidity.

Of course I do, but when the humidity is a constant, it's irrelevant. You can have high humidity and denser air than you would for the same level of humidity in a different region of the world and vise verse. Standard barometric pressure is 29.92 at 15C.

I don't pretend to be an expert on barometric pressure. All I know is that in the winter, in Vancouver the Barometric pressure is usually between 101.5 and 102 (30.11) and the humidity averages 80%, 90% in my part of the lower mainland as I live at the bottom of the North shore mountains, we get twice the rain of Richmond which is only 20 miles south. The Humidity is currently 86%. When the humidity reaches 100% I often see the barometric pressure near 101, but I have never seen it at 99.4 (not that I've noticed). Yesterday the Humidity was 90% and the barometric pressure was an abnormally low 99.4 (29.35); the ball was consistently a full club length longer than what I've come to expect playing the exact same course (and same ball) once a week during the winter. Today the Barometric pressure reached 101.5, which is a significant swing.

I was playing at 5-10 feet above sea level. Standard Barometric pressure at sea level and at 15C is 101.34 (29.92)

The only thing that could explain the extreme difference in ball flight was barometric pressure, as the humidity is typically the same during the 4 rainy months of the year. If anything, I struggle to get all the way to the pin on approach shots in the winter, I'm not expecting to airmail greens and usually don't.

Quote:

Originally Posted by David in FL 


The difference between your average barometric pressure and yesterday's "abnormally low" is only about 2%. To use the correlation you referenced previously, that would maybe account for a 5 yard increase in distance.
Maybe some wind. A bit of a flyer lie. A slight miscalculation in yardage.
Horses......

2%? You are not even close in your thinking, though I can understand how you did the math. I think a lot of people would make the same mistake. Normal barometric pressure ranges from 98 to 105 (the siberian high) (or 29 to 31) for 98% of the inhabited areas of the planet; so in order to calculate the change in pressure, one would have to calculate the percentage between these values. For example, should the Barometric pressure be 101 on monday and change to 102 on tuesday, the value would have changed by about 14%. My math isn't perfect, but I'm in the ball park. Now when the barometric pressure changes, air temperature and humidity usually also change, so the air density may not change as much. All this said, should the temp and humidity remain constant, then you have a significant difference in air pressure. As I understand it, significant drops in air pressure usually signal a storm. You could hit a golf ball 500 yards in the eye of a tropical storm...

If you followed my link, which was written by a Professor of physics, you would have seen the example whereby a golf ball would travel 10% further, given 10% lower air pressure.

Most areas of the planet do not see fluctuations of more than 5-10%, but some regions do have significantly greater swings.

Again, I'm no expert at this stuff. Yesterday was an anomaly and from time to time, I notice significant differences in ball distance, but it's usually the other way, way short. I'm talking about less than 5% of the time. I do know that since I've been following the barometric pressure, I have noticed I hit the ball further and shorter on extreme ends of the spectrum; a club lenght is extreme from monday to tuesday of the same week, it just doesn't happen often...

If it was a gust of wind following me all day, I'm going to church tomorrow for the first time in 20 years...

Quote:

Originally Posted by sacm3bill 

 

You're way off base here.  You do not calculate percentages based on an observed "normal" range. You calculate them based on the intrinsic numbers.  If a stock has traded between $95 and $105 since its IPO, and on a particular day it goes from 101 to 102, then by your logic it went up 10% that day. That's simply not the case. 

 

That was not disputed. But you'll note that nowhere in that article does the author support your incorrect definition of percentages.

For the air pressure to drop 10% from standard (101.34) as you calculate it, you'd have a barometric pressure of 91.2. The lowest ever recorded non hurricane barometric pressure in the lower 48 is 95.6. It's not possible to have a 10% change in atmospheric pressure the way you are calculating it and expressing it, it's not even possible to have a 5% change. Further, your stock can fall 25% as you calculate it, atmospheric pressure cannot (well actually it can, but you'd have to be on the wing of a plane). If on the planet earth, you would most certainly die from decompression sickness, even 10% as you calculate it would make you sick, if not kill you. So when a professor of physics or a meteorologist is describing the air pressure as changing 5 or 10%, they are not likely calculating it the way you are, since it has never happened in modern human civilization. They may also not be calculating it as I was, I already stated my math was not perfect, I'm not a meteorologist.

So it's also unlikely that a change of air pressure from 102 to 101 will only have an effect of 2% drag on an object passing through it. I'm of course not a scientist, so I can't give you definitive proof.

Get my picture now?

Maybe someone who actually knows what they are talking about can fill in the blanks...

Quote:

Originally Posted by sacm3bill 

 

I understood everything you were saying the first time. 

LOL! I just realized you're not David in FL. So you replied just to make an argument and then you say you undertood me from the start.

Do that in many threads??