Humidity/Air Quality and distance.

[David in FL]

Ok, I gotcha now. I guess altitude has more of an effect than anything.

Not to worry.....like I said, it's completely counter intuitive!

[Chas]

Not to worry.....like I said, it's completely counter intuitive!

Indeed it is and well said. Stumps a lot of pilots in the test.

[prutkows]

In a couple of words -- not really. There might be a real technical answer, but I don't know what it would be. I have found that I hit the ball a little further in the middle of summer when it is hot, then in the spring when it is still cool out. I have always attributed it to the warm air, mid-season form, loose muscles, etc. and the humidity doesn't have much to do with it. Although, I have not played in warm and dry conditions either, so I don't have much to compare it to.

Yea i've noticed it is pretty humid in Missouri. The wind here (in hawaii) is a bit stronger so it's nice to play in missouri where i don't have to focus on keeping my ball low all the time.

The molecular weight of water (H2O) is about 18. Of oxygen, it's around 32. At standard temperature and pressure, one mol of a gas occupies the same amount of space (22.4 liters, IIRC), but a mol of oxygen (or nitrogen, molecular weight of about 28) WEIGHS MORE than a mol of water vapor.

Thanks, the science makes sense to me now. Maybe i made the same mistake on my MCAT.. got a 31 lol.

[Chas]

Yea i've noticed it is pretty humid in Missouri. The wind here (in hawaii) is a bit stronger so it's nice to play in missouri where i don't have to focus on keeping my ball low all the time.

LOL.

Yes, the one time I played in Hawaii (Big Island, up a slope a bit on the W side) I almost got blown off the course and shot over 100 as I recall. Great fun tho'. The two locals I played with (big hitters) weren't at all bothered.

[prutkows]

LOL.

Yea growing up playing here really gets you accustomed to all the wind :)

[Mitch C]

Not to add another element to the conversation, but you all are forgetting about one thing: lift. Objects traveling through the air under rotational forces create lift, golf balls included. Slices and draws are evidence of rotational forces creating lift on a ball. Hit a ball with the right spin into a stiff wind and watch it balloon up because of the extra lift created.

So, it is a well known fact that humid air is less dense and therefore, creates less lift. As mentioned in this thread, pilots, particularly helicopter pilots, have known about this for a long time. Therefore, it must be concluded that golf balls generate less lift on humid days as well.

How much does lift affect the distance a golf ball goes? I don't know. I'm no expert. But it does stand to reason that on certain shots, if the spin is just right to generate lift in the proper direction, distance will be affected by the lesser amount of lift generated.

And my experience backs up what the guy from west Texas noted. I get a good deal more carry when it is hot and dry as opposed to hot and humid. When it is June and the temperature is 95 and the humidity above 50% the ball seems somewhat dead. When it is August and the temperature is 102 but the humidity 30%, then it really flies. Does the extra 7 degrees make it fly farther or is it that on the best struck balls they gain a little extra air time by generating just a bit more lift?

[PowerPutter]

Not to add another element to the conversation, but you all are forgetting about one thing: lift. Objects traveling through the air under rotational forces create lift, golf balls included. Slices and draws are evidence of rotational forces creating lift on a ball. Hit a ball with the right spin into a stiff wind and watch it balloon up because of the extra lift created.

Interesting insight about lift.

Here's an interesting link: it talks about baseballs but the discussion about air is still relevant. http://www.exploratorium.edu/baseball/howfar3.html

[Chas]

Mitch,
That is a truly fascinating post, and you introduce an important undiscussed element.

* yawn, sound of computers switching to another thread ....*

Yes, just as in aeronautics, both lift and resistance (so-called "parasitic drag") are affected by air density. As density falls (increasing elevation, increasing temp., increasing humidity), both drag and lift are reduced. So to the extent that the distance a golf ball flies is a function of lift, produced by its spinning in the air (pressure differential top-to-bottom), the effect of decreasing density would be decreased lift and thus to some extent decreased carry, other things held constant (which they would not be of course).

I would suppose that the effect of lift on ball carry would be a function of which club is used and how the ball is struck, i.e. how much spin is imparted. Clearly, a ball struck by driver will have relatively little rotation and will generate less lift than a ball struck firmly with with a PW into the wind say, when the blasted thing can seem like it's sprouted wings.

hmmm, this would suggest that if a player is prone to severe slices for example (noone on this thread of course .. ), then said player would do better playing his home course on a hot, humid day when the ball will not be so greatly affected by sidespin. I can think of a better solution to that problem tho'.

So the answer is not so simple. It depends on precisely how the ball is struck. Anyone care to come up with an equation relating golf ball carry to humidity, taking into account all known factors?


Thought not

[RC]

The high humidity, high altitude statements are spot on. The ball goes further because of lower air density. Where some get fooled is they play inland at higher elevations, then travel to a coastal area with high humidity and assume the humidity is the cause of shorter distance, when it is typically the seal level elevation that is holding them back. Science wins. The molecular weights previously stated are critical to the correct answer, as is the temperature. Heck, on a foggy day at Torrey Pines, I can hit my drive out of sight... and some of my putts.

[Mitch C]

I don't know that science is all that clear cut.

What do we know? Humid air is less dense. Less air density equals less resistance on the ball. Less resistance means a ball hit a certain speed can maintain that speed longer and go farther in a given period of time traveling at that same speed. Therefore, it would seem clear that balls travel farther in humid air that is less dense.

On the other hand, less air density means less lift generated by the ball. Lift slows the rate of descent of a ball and by so doing, allow it to stay in the air longer. Staying in the air longer, means it travels a greater distance forward before hitting the ground, all else being equal.

So, clearly it all revolves around whether less resistance that allows a ball to travel farther in a given period of time means more distance than greater lift that allows a ball to stay in the air for a greater period of time means more distance.

It is more complicated for golf balls where the rpms measure into the thousands than it is for baseballs as that the the lift could be significantly higher on a ball hit just right.

And one more thing. Air resistance has nothing to do with the rate of drop on a golf ball. That is purely a function of gravity. Less resistance allows a ball to travel farther in a given period of time. On the other hand, lift can actually slow the rate of drop on a golf ball.

[Uber$winG]

This is both an interesting and informative thread…

I’ve been wondering about this kind of phenomenon on ball flight because recently it has been humid here in Colorado, and the guy with whom I play during the weekdays maintains that because of the abnormally humid conditions he is not hitting the ball as far as he is used to. I too have been a bit shorter on my shots and I think I can attribute it to the effect the humidity has on the player’s physical fitness rather than the physics of the golf ball’s flight.

[Mitch C]

Look at bullets. Rifle bullets don't generate that much lift because they turn clockwise or counterclockwise very fast. The lift they generate is stabilizing and doesn't provide extra air time. So, here is an amazing fact. A bullet fired from the barrel of a gun, provided the barrel is exactly level, and a bullet dropped from the exact same height will hit the ground at the exact same instant. The one fired from the gun may hit the ground 3,000 feet down range, but it will hit at exactly the same instant as the one dropped from your hand. Distance is merely determined by how far that bullet can travel before it hits the ground. If the air is dense, it may only go 2,800 feet before it hits the ground as opposed to 3,000. If the air is thin, it may go 3,100 feet before it hits the ground.

Now, imagine an F-15 traveling as fast as a bullet. Imagine that the F-15 passes a point in the sky and at the instant it passes, a bullet traveling at the exact same speed is fired from a gun. And at the exact same instant as the F-15 passes that point and the bullet is fired, the F-15's engines are shut down. Clearly, the F-15 being much larger and less aerodynamic will slow down quicker than the bullet and given what we discussed above, it would stand to reason that it would not travel as far as the bullet before it hit the ground. But, introduce the element of air passing over the wings of the F-15 and creating lift and things change. Sure, the F-15 will be going slower but lift will also slow its rate of descent allowing it to stay in the air longer and go farther than the bullet even though drag is affecting it much more than it did the bullet.

So, the question is does a golf ball generate enough lift in certain circumstances in heavy dry air to slow its rate of descent enough to counteract the effects that less dense humid air would normally have on an object moving through air.

[iacas]

Mitch, since the ball basically always flies farther at higher altitude, I think it's fairly clear that the loss of lift doesn't begin to offset the additional distance that reduced density allows.

Dry and high beats wet and low.

[PowerPutter]

Is there a certain angle that is optimal for roll? I remember from physics that an object with a trajectory of 45 degrees maximizes distance, but obviously you would not get a good roll with a shot that high, and spin on golf balls and common knowledge says that this angle wouldn't maximize distance (before roll) either. What loft do long drivers use? Edit: looks like wikipedia says 4-5 but hit the ball on an upswing. http://en.wikipedia.org/wiki/Long_drive#Equipment

[Mitch C]

Mitch, since the ball basically always flies farther at higher altitude, I think it's fairly clear that the loss of lift doesn't begin to offset the additional distance that reduced density allows.

I think in general that is true. But what about wet and low versus dry and low? All of my golf is played at about 400 ft above sea level and in my experience, the ball flies better when it is hot and dry than it does when it is hot and wet. The point is that increased humidity and less air density, does not always equal greater distance and that there are lots of factors at work.

[iacas]

But what about wet and low versus dry and low?

If wet means humid, then for the same reasons that altitude matters, and for the same reasons already discussed, humid beats dry for distance. Your experience seems different than mine (again, "wet" is humid, not literally rainy weather), and different than what's commonly accepted as the truth for golf ball distance.

[Mitch C]

If wet means humid, then for the same reasons that altitude matters, and for the same reasons already discussed, humid beats dry for distance. Your experience seems different than mine (again, "wet" is humid, not literally rainy weather), and different than what's commonly accepted as the truth for golf ball distance.

As I said, I'm talking about when it is hot and wet verses hot and dry. I'm talking 95 degrees and up.

How much experience do you have playing in those kinds of temperatures? In Pennsylvania? Probably not much.

[iacas]

As I said, I'm talking about when it is hot and wet verses hot and dry. I'm talking 95 degrees and up.

And again, I think it's widely accepted that decreased air density increases distance - that the small drop in lift is more than made up for by the decrease in resistance.

It was super-hot and super-humid at the PGA at Southern Hills, and all the players were talking about was how far the ball was going. There was your 95 degrees and up type of weather.

How much experience do you have playing in those kinds of temperatures? In Pennsylvania?

Yes, because a person can't possibly have ever lived anywhere but where they currently live...

I've got a fair amount of experience playing in super-hot, humid conditions. I lived in Florida for quite awhile. And we get our fair share of freakishly hot, humid days here in PA - I live right on Lake Erie.