Air Pressure and Golf Ball Distance

[limoric]

Originally Posted by Golfingdad

Umm, this is a forum.  Everybody does that on every thread.  If you want to have a private conversation with David in Florida then start a PM with him.  Several people read these and comment when they feel they have something to add.

And since I'm here, I agree with Sacm and David regarding how you calculate percentages, and furthermore, agree with David regarding his hoofbeats parable.  I think you might be waaaaay overthinking this.

You're telling me that everyone thread jacks on every thread. Listen, only A$$ holes posts stupid comments just to pad their thread count or start arguments just to argue; the glass is always half empty with you guys. With 1,800 posts in less than a year, I can see that you've been busy posting a lot about nothing. Where do you find the time to golf, let alone look after your family...my God man!

Now as to your comment about calculating percentages; it has nothing to do with the expression of change in air pressure or drag. Clearly you have not read the entire thread; a 10% change in Air pressure as Sacm is calculating is not physically possible outside of a hurricane, yet he does not dispute the effects of a 10% change on the flight of a golf ball. LOL, I'm glad you agree with him...

Now before you reply, I'm fairly certain the thread jacking rules have not changed in the 5 years I've been a member here, kindly buzz off so that I don't have to get moderators involved. I won't $hit on your threads either...

[limoric]

Originally Posted by sacm3bill

I understood what you were saying. That doesn't mean I agreed with it. So I pointed out you were wrong. You then re-explained your thought process, which I understood the first time, hence the "I understood the first time". That was meant to convey that the reason I disagreed with you was not because of a misunderstanding, or because I needed clarification. I disagreed with you because I think you're wrong.

Clear now?

Wrong about what? So you are not agreeing with me that it is not possible for barometric pressure to fall from 101.34 (standard) to 91.2, 10% as you would calculate percentages. You are not agreeing with me, even though the lowest non hurricane barometric pressure recorded in the lower 48 is 95.6.

OK, thanks for the arguement.

[luu5]

Originally Posted by limoric

Now as to your comment about calculating percentages; it has nothing to do with the expression of change in air pressure or drag. Clearly you have not read the entire thread; a 10% change in Air pressure as Sacm is calculating is not physically possible outside of a hurricane, yet he does not dispute the effects of a 10% change on the flight of a golf ball. LOL, I'm glad you agree with him...

People are arguing that you do not do percentage calculation like you did. If I read correctly the original article you linked, there was no mention how the 10% was calculated. Could be like you explained, could be not.

But as your HC is 5.6, you must be correct

[David in FL]

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...

I didn't find anything in the link you provided to indicate that a percentage change in barometric pressure is calculated, or expressed any differently than anything else. Regardless though, if you feel that it affects your game so much that you want to factor it into your club selection, have at it. Personally I have more than enough factors to consider already, so unless I'm traveling to someplace with a significant change in altitude or average relative humidity, I'm going to leave the barometric pressure alone. If you are interested in getting a more accurate feel for how the local conditions will affect the carry of your ball though, you might want to consider calculating the density altitude for your course and daily conditions. That will factor in humidity and temperature to give you an idea of how your course will play compared to standard conditions. Pilots use it to determine aircraft performance, primarily in calculating takeoff and landing requirements. Here's a link. http://www.flyingmag.com/technique/tip-week/calculating-density-altitude-pencil

[Bananarama]

I saw this the other day: http://www.srixon.com/index.php?alias=srixonuniversity - goto the environment part.

I also googled it and got some golf WRX thread from 2009.

[iacas]

Originally Posted by limoric

You're telling me that everyone thread jacks on every thread. Listen, only A$$ holes posts stupid comments just to pad their thread count or start arguments just to argue; the glass is always half empty with you guys. With 1,800 posts in less than a year, I can see that you've been busy posting a lot about nothing. Where do you find the time to golf, let alone look after your family...my God man!

Now before you reply, I'm fairly certain the thread jacking rules have not changed in the 5 years I've been a member here, kindly buzz off so that I don't have to get moderators involved. I won't $hit on your threads either...

I'm one of the owners of this site, and as such, a moderator. The topic of this thread is "air pressure and golf ball distance" so discussing golf ball distance as a result of properly measuring or calculating "air pressure" (and density) is on topic.

If anyone is to receive a warning (or more), it's you for the bold part and in fact the rest of that first paragraph.

In other words, I see no thread jacking going on, but I do see someone being a bit of a jerk, and unfortunately, it's you. Chill out. Respond to the criticisms to your math, as it seems to me perfectly on topic.

[sacm3bill]

Originally Posted by limoric

Quote:

Originally Posted by sacm3bill

I understood what you were saying. That doesn't mean I agreed with it. So I pointed out you were wrong. You then re-explained your thought process, which I understood the first time, hence the "I understood the first time". That was meant to convey that the reason I disagreed with you was not because of a misunderstanding, or because I needed clarification. I disagreed with you because I think you're wrong.

Clear now?

Wrong about what? So you are not agreeing with me that it is not possible for barometric pressure to fall from 101.34 (standard) to 91.2, 10% as you would calculate percentages. You are not agreeing with me, even though the lowest non hurricane barometric pressure recorded in the lower 48 is 95.6.

OK, thanks for the arguement.

It's irrelevant how much change is "possible".   What you're wrong about is when you speculate that a 2 or 3 Pa change in pressure can result in a 10% change in carry distance, as you did in your first post.  David pointed out that the pressure change from say, 101 to 102 was only 1%. You claimed it was more like 14%. That is where you're wrong.  Please believe me when I tell you that in no scientific community is the "normal range" of a value taken into account when measuring the percentage change of that value.

Originally Posted by David in FL

...Regardless though, if you feel that it affects your game so much that you want to factor it into your club selection, have at it.

Exactly. If your beliefs help your game, more power to you.

[Bananarama]

Just to nit pick about normal range, but loads of people use temperature in degC rather than in K, so a rise by 1 degree at 1degC = a 100% rise in temperature but in K the same % temperature rise is (1/274.15)*100

I dont think scale is the issue here though, if it only takes 1 or 0.5Pa change in pressure for a significantly different result then thats would be fine and it would be interesting to find a quantitative measure.

[Golfingdad]

Originally Posted by limoric

You're telling me that everyone thread jacks on every thread. Listen, only A$$ holes posts stupid comments just to pad their thread count or start arguments just to argue; the glass is always half empty with you guys. With 1,800 posts in less than a year, I can see that you've been busy posting a lot about nothing. Where do you find the time to golf, let alone look after your family...my God man!

Now as to your comment about calculating percentages; it has nothing to do with the expression of change in air pressure or drag. Clearly you have not read the entire thread; a 10% change in Air pressure as Sacm is calculating is not physically possible outside of a hurricane, yet he does not dispute the effects of a 10% change on the flight of a golf ball. LOL, I'm glad you agree with him...

Now before you reply, I'm fairly certain the thread jacking rules have not changed in the 5 years I've been a member here, kindly buzz off so that I don't have to get moderators involved. I won't $hit on your threads either...

No, not everybody thread jacks, but he wasn't thread jacking.  Every post of his (and Davids) was precisely on topic.  Furthermore, Sacm was the FIRST PERSON to respond to your thread, yet you implied that he popped into a conversation that wasn't his just to start an argument.  Every last post on this thread is dead on topic - other than this one - so just relax and discuss.

(I'm choosing to ignore the rest of your first paragragh)

[sacm3bill]

Originally Posted by Bananarama

Just to nit pick about normal range, but loads of people use temperature in degC rather than in K, so a rise by 1 degree at 1degC = a 100% rise in temperature but in K the same % temperature rise is (1/274.15)*100

I dont think scale is the issue here though, if it only takes 1 or 0.5Pa change in pressure for a significantly different result then thats would be fine and it would be interesting to find a quantitative measure.

Agreed, the units matter, especially when the systems define different points as zero, and the percentages will change depending on that. I'm just saying that the observed normal range ("from 98 to 105... for 98% of the inhabited areas of the planet", as limoric put it), does not come into play when figuring percentage change.

For the reasons you point out though, "percentage change" is probably not a good way of describing a change in pressure. So we're left wondering what is meant by a "10%" change.

[boogielicious]

It is sad how all these promising threads always down grade into bickering.  I don't know why.  Maybe people just misread the OP or the responses and it just does a death spiral from there.  In the spirit of the holidays (any holiday), let's all try to be a bit more civil.

Back to the original subject.  We are discussing three factors that affect air density, temperature, humidity and barometric pressure.  It is a bit of a complicated calculation.  But I will try to put some numbers up for digestion of the nerdy crowd like me.

Barometric pressure - a quick calculation of a 994 mbar BP shows this would be equivalent to only 150 meters altitude gain.  994mbar/1.333 = 745.6mmHg  (1mmHg = 1.33322368 mBar ) .  From the linked chart we get about 150 meters altitude.

source:  http://www.engineeringtoolbox.com/air-altitude-density-volume-d_195.html

Humidity - we are stating that humidity is not varying much, but for information, the density can be calculated.

source: http://www.engineeringtoolbox.com/density-air-d_680.html

Lastly temperature:  We all know cold air is more dense.

http://www.engineeringtoolbox.com/air-temperature-pressure-density-d_771.html

Putting it all together:  I found this calculator on line;

http://www.denysschen.com/catalogue/density.aspx

Air density for 46F, 80% humidity normal BP of 760 (sea level) would be 0.0778 lbs-m/ft3

Air density for 46F, 80%, 994mbar (or 150 meters - 492 feet) would be 0.0764 lbs-m/ft3 or about 2% difference.

The effect of density on distance is a bit more complicated.  From this source. http://www.golf-simulators.com/physics.htm, and the equations below, it looks like there is a linear relationship.

where p is the density of air at sea level.  But drag coefficients will also vary with temperature and therefor density.  I couldn't find anything on that.  Both the X and Y components are affected the same.  So we have to make an educated assumption that the distance affect, all things being equal except barometric pressure, would only account for 2% change in distance.

None of the equations above have been verified, so we will have to accept them as is.  Feel free to find errors in my assumptions.

Unless we are missing a factor, on a 125 yard shot you would only gain about 2.5 yards.  But that may be enough to overshoot the green.

BTW, in New England this time of year, if the BP was down at 994, it would be blowing like crazy!  We rarely get low BP and calm weather unless we are in the eye of a N'or Easter.

[limoric]

Since my last post, some people have added to the actual theme of the thread; it was my intention to draw these smart people in. Yes, it's said it went the way it did.

I did not start this thread to Argue, I made it very clear I was no expert from the beginning. Some have also pointed out the rudeness of just a few posters, (they are not referring to me). Please re-read this thread and consider who was actually being the jerk. If the "owner" and "moderator" of this board will not defend those who would try to have civil conversation, then they have no choice but to defend themselves in whatever fashion they feel effective. I'll admit ignored the moronic behavior might have been more effective...these guys are still auguring moot points which have nothing to do with the subject matter.

Mod Edit: Parts where you call other people "jackasses" have been removed. Behave maturely.

[limoric]

Originally Posted by sacm3bill

It's irrelevant how much change is "possible".   What you're wrong about is when you speculate that a 2 or 3 Pa change in pressure can result in a 10% change in carry distance, as you did in your first post.  David pointed out that the pressure change from say, 101 to 102 was only 1%. You claimed it was more like 14%. That is where you're wrong.  Please believe me when I tell you that in no scientific community is the "normal range" of a value taken into account when measuring the percentage change of that value.

Please prove this. Your stock example was an attempt to make me understand how to calculate percentage, but clearly, even in your example, the math would not be possible. Air Pressure can change 5-10%, the professor of physics I linked to said as much, but if I apply your math to this change, you get a number that isn't even possible. So where my math is clearly not correct and I said it wasn't from the start, your math is absurd and your posts have done absolutely nothing to explain the effects of Air Pressure on golf ball flight.

I fully expect to get an arguement from you without a single attempt to prove your possition...

[limoric]

Originally Posted by boogielicious

It is sad how all these promising threads always down grade into bickering.  I don't know why.  Maybe people just misread the OP or the responses and it just does a death spiral from there.  In the spirit of the holidays (any holiday), let's all try to be a bit more civil.

Back to the original subject.  We are discussing three factors that affect air density, temperature, humidity and barometric pressure.  It is a bit of a complicated calculation.  But I will try to put some numbers up for digestion of the nerdy crowd like me.

Barometric pressure - a quick calculation of a 994 mbar BP shows this would be equivalent to only 150 meters altitude gain.  994mbar/1.333 = 745.6mmHg  (1mmHg = 1.33322368 mBar).  From the linked chart we get about 150 meters altitude.

source:  http://www.engineeringtoolbox.com/air-altitude-density-volume-d_195.html

Humidity - we are stating that humidity is not varying much, but for information, the density can be calculated.

source: http://www.engineeringtoolbox.com/density-air-d_680.html

Lastly temperature:  We all know cold air is more dense.

http://www.engineeringtoolbox.com/air-temperature-pressure-density-d_771.html

Putting it all together:  I found this calculator on line;

http://www.denysschen.com/catalogue/density.aspx

Air density for 46F, 80% humidity normal BP of 760 (sea level) would be 0.0778 lbs-m/ft3

Air density for 46F, 80%, 994mbar (or 150 meters - 492 feet) would be 0.0764 lbs-m/ft3 or about 2% difference.

The effect of density on distance is a bit more complicated.  From this source. http://www.golf-simulators.com/physics.htm, and the equations below, it looks like there is a linear relationship.

where p is the density of air at sea level.  But drag coefficients will also vary with temperature and therefor density.  I couldn't find anything on that.  Both the X and Y components are affected the same.  So we have to make an educated assumption that the distance affect, all things being equal except barometric pressure, would only account for 2% change in distance.

None of the equations above have been verified, so we will have to accept them as is.  Feel free to find errors in my assumptions.

Unless we are missing a factor, on a 125 yard shot you would only gain about 2.5 yards.  But that may be enough to overshoot the green.

BTW, in New England this time of year, if the BP was down at 994, it would be blowing like crazy!  We rarely get low BP and calm weather unless we are in the eye of a N'or Easter.

Wow, awesome info...thanks.

[Paradox]

all I know is that a pressure change from 101 to 102 would result in a percentage change of .9%

(new value - old value)/ old value = n x 100 = % change.

[limoric]

So I played in an event today at Swan-E-Set Golf course just north of Pitt Meadows BC, this is about 30 minutes north east of Vancouver. Even though the course is around a 1 hour drive from the nearest coastline, the area is below sea level. It's a place where golfers now their ball is not going to fly as far, the same goes for Golden Eagle golf course which is 10 minutes from it. I played with 7 cap, an 8 cap and of course I'm a 6 for this course.

Where I was hitting wedge 135 just 2 days ago (10 minutes from the coastline, but a few feet above sea level), today I was lucky to hit a wedge 115 and my playing partners were no different, we were all talking about loss of distance. 160 approach shots required 5 iron; even in the winter, 5 iron goes about 170-175 for me at most Vancouver courses.

The temperature was exactly the same today as Sunday. The humidity was roughly the same, 93% in the nearest town, 10 minutes away. Sunday it was 88-90% in North Vancouver. I don't know what the barometric pressure was, since I was not carrying a barometer, but in the nearest town it was 100.2 today, which is lower than normal, we are in the middle of a low pressure system which started Sunday. Since the course is below sea level and sea level pressure in 101.34, I can only imagine the pressure was higher, perhaps 2 points higher than Sunday's 99.4.

For those who have participated in this thread, and those who will. It's a fact that air pressure fluctuate greatly in some areas of the planet and very little in others. If you don't see a significant change in golf ball distance from one week to the next, it's very likely the air pressure in your area does not change much. If on the other hand, you wonder why the ball just doesn't fly sometimes, it may be the air pressure, but as others have already said, temperature and humidity can be influencers. I'm more interested in ball flight distance changes when the temp and humidity are constant

[limoric]

Originally Posted by Paradox

all I know is that a pressure change from 101 to 102 would result in a percentage change of .9%

(new value - old value)/ old value = n x 100 = % change.

It might very well, but I would be very surprised if the effect on air density was just 0.9% and that's what this thread is about.

The physics professor in the link I posted previously made reference to a 10% change in air pressure and the influence on golf ball distance (a 240 yard drive would be 267). He also made references to change in air pressure not being more than 5-10% usually. Since it is impossible for the air pressure to drop 10% by the way you are calculating it, he must be talking about a different unit of measure. The lowest recorded non-hurricane barometric pressure in the lower 48 is 95.6 and it most certainly did not get to that value overnight.

[limoric]

Originally Posted by sacm3bill

Agreed, the units matter, especially when the systems define different points as zero, and the percentages will change depending on that. I'm just saying that the observed normal range ("from 98 to 105... for 98% of the inhabited areas of the planet", as limoric put it), does not come into play when figuring percentage change.

The percentage change doesn't matter and I don't care what it is. I'm after the percentage change in air density or the percentage change that an object is affected by when passing through that air density. It's the point of the whole thread, you could have chosen to look at it a different way, despite how you understood my description..