How weather conditions affect a golf shot

• I
• Fisic
In summary, atmospheric conditions such as temperature, pressure, and dewpoint can greatly affect the performance of a golf ball. The drag force on the ball, which is affected by air density, can vary by 11.2% between winter and summer conditions. The temperature of the ball's interior can also impact its elasticity and overall performance. This is why golfers may see a difference in distance and roll when playing in different weather conditions.
Fisic
Please correct me if I'm well off the fairway with the following theory.

We all know that atmospheric conditions (temperature, pressure, dewpoint, etc.) can affect many different bodies in motion, from aeroplanes to cars to golf balls. But in the case of a golf ball, exactly how big is the effect? How much more club do you need in the winter versus the summer?

Let's assume wind is calm and we're playing a golf course at sea level. Round 1 is played on a dull winter morning, temperature 0 °C, relative humidity 80%, while Round 2 is on a sunny afternoon in mid-July, temperature 28 °C, relative humidity 70%. Assume in both cases atmospheric pressure is the standard 1013 hPa.

The only differences in conditions are therefore the air temperature, specific humidity (as measured by dewpoint) and ground temperature (which greatly affects the temperature of the ball and hence the compressibility of its elastomeric core). In summer, the grassy surface can get several degrees warmer than the overlying air, so assume it's 35 °C in this case. In winter, assume it's the same as the air (or else there would be ground frost and the course would be closed).

The density of the air is the primary factor affecting the aerodynamic performance of the golf ball and is calculated for both scenarios below (using the Density Altitude tool in the Aviation Pocketknife app). The density of 1.290 kg/m³ in winter is 11.2% higher than in summer (1.160 kg/m³).

 Air Relative humidity Dewpoint Air density [kg/m³] Ground temperature Round 1 0 °C 80% -3 °C 1.290 0 °C Round 2 28 °C 70% 22 °C 1.160 35 °C

The drag force (air-resistance), FD, felt by the ball is given by the expression

FD = ½ρCD2

where CD is the Coefficient of Drag of the ball and A its area facing the air, both the same in the two scenarios and therefore constant, and ν is its speed. The only difference is therefore the air density, ρ. In summer, the drag force is 11.2% lower than in winter, therefore the ball will travel that much further, all other things being equal. If you get 140 yards from your 9-iron in the winter scenario you're talking around 155 yards in summer (i.e about a 1-club difference). A 250-yard winter carry becomes near 280 yards in summer (and the numbers get crazy for DeChambeau and Bubba...)

In reality, all other things are not equal and other factors are at play, primarily the ground (ball) temperature. As the golf ball is lying on the ground for the vast majority of the time, the temperature of its elastomeric core will adjust towards the ground temperature during the round. I read somewhere that the ideal core temperature is 27 °C (though I'm sure it varies for different balls brands), therefore in the winter scenario we can expect the core to cool down towards 0 °C as the round progresses. This will reduce the compression and spring off the clubface and therefore take distance off the shot, but exactly how much I'm not sure. Anyone? I always store my golf balls indoors overnight before I play winter golf here in Ireland and keep a spare ball in each pocket, switching balls between holes. It does keep the balls warmer than if they were in my bag and I do see and feel a difference, but I'm just not a good enough golfer to be able to quantify this accurately.

In summer, the core is closer to the optimum temperature and therefore distance is maximised. Also, the ground will most likely be harder, adding more rollout to the shot. I said above that the only difference in the drag equation is the air density, however the launch speed of the ball will probably differ too, being faster with the warmer core in the summer.

Overall, we have around 11% lower air-resistance, a faster ball speed and longer roll in summer. The optimum conditions are on a warm, humid day with low atmospheric pressure, while the worst are on a cold, dry day in a winter anticyclone. If the winter and summer pressures are changed to 1030 and 990 hPa, respectively, the air densities and therefore drag forces change by even more, by around 15.6%. That's 15 extra yards for every 100, or 45 yards on a 300-yard drive. No wonder these guys regularly hit it 330+ on the PGA Tour.

If anyone has any more detailed info on the important factor of ball temperature and its effect on impact dynamics I would love to hear it.

jrmichler
You did a good job of identifying the effect of air resistance. The effect of temperature on the rubber ball interior is a little more complicated. The rubber inside golf balls is an elastomer, and elastomers have properties that vary with temperature. There are two different properties that are most significant:

1) The modulus of elasticity
and
2) Hysteresis, also known as damping

Modulus of elasticity is stretchiness - how much it stretches under a given stress. The modulus of elasticity of elastomers is nonlinear because it is a function of the stress. Hysteresis is energy absorbed and turned into heat during the act of stretching. Both of these properties are a function of temperature. I did not find a plot of material properties for the rubber used in golf balls, but did find on for some random elastomers:

Note that both the elastic modulus (spring rate), and the hysteresis (damping factor) in the above plots vary significantly over the range of temperatures that you mention. The rubber used in golf balls will be different, and there are other elastomers where the properties vary at higher and lower temperatures. Do not use this figure for golf balls.

Fisic
I thinkit far too evident to most golfers that the effect of spin-induced lift is non-trivial. I have hit some drives that have sliced nearly as far as they have travelled. I think these are essentially Magnus Effect forces mediated by the dimples on the spinning ball. Probably they will mitigate some of the negative effects of the thicker air by providing lift...(??) Not negligible for this I think.

Fisic and berkeman
Magnus effect is certainly relevant for distance travelled. But the dimples are as far as I know for the reduction of resistance by reducing the wake:

By the way, temperature affects viscosity. And viscosity together with density affect the Reynolds number. And since the drag of a golf ball is dependent on the Reynolds number this will also have some effect, But I think not that big for this case. This is from wikipedia (smooth: no dimples, rough: with dimples, so according to this graph Cd only gets smaller by the dimples in a very specific region of Reynolds numbers... I don't know what's true):

jrmichler said:
You did a good job of identifying the effect of air resistance. The effect of temperature on the rubber ball interior is a little more complicated. The rubber inside golf balls is an elastomer, and elastomers have properties that vary with temperature. There are two different properties that are most significant:

1) The modulus of elasticity
and
2) Hysteresis, also known as damping

Modulus of elasticity is stretchiness - how much it stretches under a given stress. The modulus of elasticity of elastomers is nonlinear because it is a function of the stress. Hysteresis is energy absorbed and turned into heat during the act of stretching. Both of these properties are a function of temperature. I did not find a plot of material properties for the rubber used in golf balls, but did find on for some random elastomers:
View attachment 294170
Note that both the elastic modulus (spring rate), and the hysteresis (damping factor) in the above plots vary significantly over the range of temperatures that you mention. The rubber used in golf balls will be different, and there are other elastomers where the properties vary at higher and lower temperatures. Do not use this figure for golf balls.
Yes, and the Coefficient of Restitution seems to be the parameter measured to cover both of these properties. The core of most balls is made of various cis-grades of Polybutadiene, but I haven't found much more detail than that. I feel an experiment coming on...dropping balls from different heights (h) at different temperatures and measuring the rebound heights hR.

CoR = e = √(hR/h)

Values of e generally seem to be around 0.9 on Google.

jrmichler
Arjan82 said:
Magnus effect is certainly relevant for distance travelled. But the dimples are as far as I know for the reduction of resistance by reducing the wake:
My point is that the lift from the Magnus force is also proportional to the air density. Therefore the lift/drag ratio for the golf ball will not depend upon air density. How much of its range is due to aerodynamic lift ? I would suppose folks have done studies using various backspin to answer this question.

1. How does wind affect a golf shot?

Wind can significantly affect a golf shot by altering the trajectory and distance of the ball. A strong headwind will cause the ball to travel shorter distances, while a tailwind will help the ball travel further. Crosswinds can also cause the ball to drift off course, making it important for golfers to adjust their aim and club selection accordingly.

2. Does humidity affect a golf shot?

Yes, humidity can affect a golf shot by making the air denser. This can cause the ball to travel shorter distances due to increased air resistance. Additionally, high humidity can also make the grass and ground more damp, which can affect the roll of the ball on the green.

3. How does temperature affect a golf shot?

Temperature can affect a golf shot in several ways. In colder temperatures, the ball will not travel as far due to the air being denser. On the other hand, in hotter temperatures, the ball may travel further due to the air being less dense. Extreme temperatures can also affect the ball's compression, which can impact its distance and trajectory.

4. What impact does rain have on a golf shot?

Rain can have a significant impact on a golf shot. Wet conditions can cause the ball to not roll as far on the green and can also make it more difficult to control the spin and trajectory of the ball. Additionally, heavy rain can also affect a golfer's grip on the club, making it more challenging to hit accurate shots.

5. How do different types of weather conditions affect club selection?

Different weather conditions can require golfers to adjust their club selection. For example, in windy conditions, a golfer may need to use a lower lofted club to keep the ball from being affected by the wind. In wet conditions, a golfer may need to use a longer club to compensate for the reduced roll. Additionally, in extreme temperatures, golfers may need to use a different type of ball that is better suited for the conditions.

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