The 30-second takeaway message is wind at the surface of the green matters once your pants legs are flapping, and the golfer should learn the effects of strong winds by discriminating among headwinds, tailwinds, and crosswinds, as well as strength or wind speed perception and steadiness and its effect on long and short putts on slow and fast surfaces in terms of line and distance and how to play breaking putts. Surface wind is similar to slope and grain, with headwinds having the most pronounced effect on putts when the ball is rolling slowly. When the wind is strong enough to challenge balance, the golfer can "take in sail" by setting up in a low and compact posture with wider stance and a lower and tighter grip, and use a more decisive stroke.
Sorts of winds. There are many sorts of winds, such as the jet stream, the trades and Westerlies, sea breezes and land breezes, mountain downslope winds, cyclones, tornadoes, hurricanes, gales, squalls, gusts, and more. What matters in golf is a mid-range of ground winds and certain prevailing regional patterns. Once the wind is strong enough to make
the material on your pants legs flap like flags on
a sailboat (about 10-15 mph), beware of putting upwind
or downwind and allow for crosswind to influence the
break or line of lengthy putts.
When the wind blows on your face, that doesn't necessarily matter, since green slope and fringe mounding may be blocking ground-level wind from influencing the ball -- so check the pants legs. Also, you can putt out of calm areas into windy areas and vice versa, so watch that also. In general, wind speed increases with clearance above the retarding influence of ground, vegetation, and terrain, because wind is a "mass" of air in motion, and motion nearest the surface is slowed and stirred and blocked by ground-level interference. Wind high at the tops of the trees is likely blowing substantially stronger and steadier than wind low across the green surface, and this is why today's wind turbine's are built atop towers extending 100+ feet high and located on hilltop terrain unblocked from the prevailing winds (see the wind power profile law).
NASA wind smoke test showing stronger wind at upper blade.
The properties of wind are direction, force, density and steadiness. The ready-to-hand indicator, just like an airport runway "wind sock", is the flag in the hole. The direction the flag extends in the wind shows which way the wind blows, the degree to which the flag flutters or flap and how straight it extends indicates the force or wind speed, and the steadiness can be seen in the steadiness of the rhythm of the flag's waving. Density is partly temperature and partly humidity and partly altitude. Other ready-to-hand indicators include the bottom fabric of your trousers, fallen leaves blowing across the green or fairway nearby, greenside trees, nearby grasses (especially tall tufts), soaring birds, long hair, and of course the toss of loose grass blades.
Wind speed is expressd often in knots, miles per hour, meter per second, or kilometer per hour. This wind speed converter calculator from the National Weather Service comes in handy.
Physics of Wind-ball Interaction. Wind is a mass of air in motion, and the movement is caused by pressure differences in the atmosphere such that air mass in high pressure moves towards areas of low pressure. Local effects of air mass in motion include eddies and swirls as the air mass collides with terrain and objects and other air masses. As any sailor knows, the force any wind exerts on an object depends upon the cross-sectional area the objects presents to the wind's direction (bigger sails move the boat faster with greater power). As every cyclist and Formula 1 racer knows, reducing the profile for better "aerodynamics" reduces the opposing force of the wind and makes the power of cycling or driving go faster with less energy wasted fighting the wind. But the ball cross-sectional area is fixed.
The aerodynamics of a golf ball opposed by the wind or aided by a tailwind depends upon the the wind speed and direction relative to the ball speed and direction, the cross-sectional area of the ball, and the density of the air mass. The formula is:
Fd = -0.5ρv^2ACd
where;
Fd = the force of drag,
ρ = the density of the fluid [at sea level, dry air is 1.2 kg/m3 at 20°C and 1.29 kg/m3 at 0°C],
v = the speed of the object relative to the air (squared = ^2) [e.g., a 10-foot putt on a Stimp 10' green has a ball speeds starting out around 80 inches/sec. or 2 meters/sec., slowing progressively to zero, with the more telling effect being as the ball speed slows to zero late in the putt; the "relative" ball wind speed will be the resulting difference of the ball's speed and direction vector and the wind's speed and direction vector integrated over the entire path]
A = the cross sectional area of the object [all golf balls have diameter 1.68" or 0.0426 meter and area 0.134 m^2],
Cd = the drag coefficient [for smooth spheres like a golf ball, Cd ~ 0.5].
The main factor is relative speed, which is squared as a factor of drag. The ball mass and size and cross-sectional area are fixed, the co-efficient of drag doesn't change at all due to dimples at speeds less than 55 mph (some longer putts go that fast only briefly at the beginning but usually jusy ignore this effect), and the air density doesn't change that much and is at any rate pretty much fixed for the day.
The density of the air is mostly a matter of elevation above sea level, temperature, local barometric pressure, and humidity. The density of air is generally greater near sea level than in the high mountains, greater in colder weather, and greater in high pressure, but less in high humidity (as water molecules have less mass than air molecules in the same volume, so a given volume of air has less total mass when that volume is humid compared to dry air). Air density for various temperatures is:
Temp. θ in °C (°F)
Air Density ρ in kg·m−3
+35 (96)
1.146
+30 (86)
1.164
+25 (77)
1.184
+20 (68)
1.204
+15 (59)
1.225
+10 (50)
1.247
+5 (41)
1.269
0 (32)
1.292
How the air density, direction and speed affects the rolling ball is a bit of a trick. The cross-sectional area of the ball and the wind-ball relative directions and speeds of ball into wind create a high pressure resistance on the front of the ball and a low pressure "drag" behind the ball that is like attaching a tail to a kite or a tail-fin to a glide plane. This added "tail " or "drag" both slows the ball down and also directs the ball's path into the wind's direction. The more direct the ball roll into the wind, the greater the "drag", so sidewinds and various crosswinds create some pressure against the ball's cross-sectional area, but the relative ball-wind speed in these cases results in not so much "drag" along the ball's line of roll as happens when the ball heads straight into the wind and the net result is a smaller effective "drag" located between the wind direction and the ball direction. A little paradoxical is the cross-effects of ball speed in wind: the faster the ball rolls, the greater the "drag" slows and steers the ball, but also the faster the ball the less time the wind has to affect the roll.
Consequently, wind acts like break and grain at once. Wind effectively sticks a dab of mud ("drag") on the ball that imbalances it the same way slope imbalances a ball, and the mud dab "turns" the ball's roll according to the location of the mud and its size. That's what slope and gravity do also. Tailwinds less than the ball speed reduce the size of this mud and tailwinds faster than the ball effectively sick a dab of mud on the front area of the ball. Balls rolling directly in line with a headwind get slowed down, but also get steered to stay on line more than balls rolling in calm air.
For the wind influence on ball direction, perhaps a better image is that of the wind vane. Wind for direction X influences ball rolling in direction Y by "steering" the ball onto the wind's heading, the same way the wind steers a wind vane. The tail of the vane with a dab of mud both influence the direction of the roll similarly. The magnitude of the influence and the effect on the actual curving path of the ball depend upon the relative forces of wind and ball, given their speeds and directions and the density of the air.
The "effect" wind has on a rolling ball will depend upon the total sum of instantaneous effects of wind vector (both speed and direction of speed relative to the ball) and the ball vector at each point along the path. Hence, the longer the wind operates before the hole is reached, the greater the effect. Playing less break in the wind is similar to keeping an iron show "below" the wind, but there is a limit of how fast the ball's delivery speed can be played before the trade-off becomes negative. Sometimes, the golfer should simply accept the wind and play the wind as it is. The real trouble comes from changeable, gusting winds. That's like playing a green with the surface contour and slope or green speed changing right after you start the ball rolling!
Regional Wind Patterns. In the "mid-latitudes" in the Northern Hemisphere -- 35 to 65 degrees North latitudes and the same in the South 35-65 latitudes -- the prevailing winds are Westerlies, mostly from the southwest to the northeast.
For safety purposes in construction, the industry guide is a map of wind velocity maximum 3-second bursts expected regionally over a 50-year span.
Locally specific situations, like the Santa Ana mountain winds in California, the Boulder Colorado downslope Rocky Mountain winds, the Canadian and prairie Chinook (southern Alberta, Wyoming and Montana, with gusts of hurrican force), and coastal winds are not covered by this map. The Santa Ana and the Boulder downslope winds can exceed 100 mph. The East Coast pattern derives from hurricanes and the Alaska pattern relates to the Bering Sea. A list of "local winds" worldwide includes 55 named seasonal patterns. Areas where mountain valleys and mountain passes compress and speed up the air flow have accelerated wind speeds and turbulence (Bernoulli effect).
Daily temperature differences underlie sea breezes (headed inshore in thre morning and offshore in the evening) and pressure and moisture extraction are features of winds on mountain slopes (upslope with cool and rain from the windward side and downslope with dry and warmer air onto the lee side). Mountains can also block air flow and divert it upstream along a range, increasing wind speed up to 45%. Lenticular clouds near the mountain tops often accompany downslope winds ("Uh oh, here comes trouble!")
The Canadian map of isotachs (equal wind speed lines) for the 50-year maximums is:
Average wind speeds are measured at 10 m (33 feet) in the map below:
Wind "barbs" are symbols indicating wind direction and speed, with a triangle being 50 knots and tall spikes for each 10 knots and a half spike for 5 knots, and the wind coming from the back of the line where the largest and first speed indicator is located. The wind symbol looks like a weather vane showing the "tail" as the direction from which the wind arrives.
1 Knot = 1.15 Miles Per Hour (MPH)
1 Knot = 1.9 Kilometers Per Hour (KM/HR)
Each short barb represents 5 knots, each long barb
10 knots. A long barb and a short barb is 15 knots, simply by adding
the value of each barb together (10 knots + 5 knots = 15 knots).
If only a station circle is plotted, the winds are calm.
Pennants are 50 knots.
Therefore, the last wind example in the chart below
has a wind speed of 65 knots. (50 knots + 10 knots + 5 knots).
A National Weather Service "wind advisory" is issued when sustained wind speed is between 30 and 39 mph with gusts from 40 to 57 mph, likely to cause power outage, property damage, and driving hazards. The NWS advisories and warnings for wind speed are:
"small craft advisory"
25 to 38 mph Beaufort 6-7
"wind advisory"
30 to 39 mph, with gusts from 40 to 57 mph Beaufort 7-8
"gale warnings"
39 to 54 mph Beaufort 8-9
"high wind warning"
40 to 57 mph Beaufort 8-10
"tropical storm warning"
39 to 73 mph Beaufort 8-11
"severe thunderstorm warning"
58 to 73 mph Beaufort 10-12
"hurricane warnings"
74+ mph Beaufort 12
"extreme wind warning"
115+ mph hurricane landfall
Perceiving wind and the influence of the wind on putts.
In the main, wind affects putting for distance, line, and break in a pattern very similar to grain -- down grain, into the grain, and across grain each having different effects depending upon ball speed, green speed, and uphill/downhill influences.
Core "Wind Putt" for Basic Effect Calibration. On a windy day, go to the practice green and try to find a level 10-foot putt into a headwind and see how the wind affects your touch for getting the ball all the way to the hole. The putt the same distance downwind. Then try crosswind. If the crosswind blows the ball enough to go off line, note how far off the ball rolls in that wind, on that green speed, for a 10-foot putt and sock it away for reference later when you play under those conditions. One great way to learn the effects of wind on putts is to putt on a fine-grained, flat, evenly sloped beach at low tide where there is a strong steady wind -- dig a small 4.25" "cup" and putt from various distances and directions. Daytona Beach is truer and faster than Augusta National on a Sunday in April!
Perceiving "Force" of Winds. For perceiving the FORCE of the wind, sailors and meteorologists have long used scales that relate sensory experience with the dry numbers of scientific measurement. Here is the Beaufort Wind Scale, as modified since 1806, with the meaningful winds in Scales 3-7 and the most important winds in Scales 4-6:
Small wavelets. Crests of glassy appearance, not breaking
Wind felt on exposed skin. Leaves rustle.
3
Gentle breeze
12 – 19
8 – 12
7 – 10
3.4 – 5.4
0.5 – 1
2 – 3.5
Large wavelets. Crests begin to break; scattered whitecaps
Leaves and smaller twigs in constant motion.
4
Moderate breeze
20 – 28
13 – 17
11 – 15
5.5 – 7.9
1 – 2
3.5 – 6
Small waves with breaking crests. Fairly frequent white horses [whitecaps].
Dust and loose paper raised. Small branches begin to move.
5
Fresh breeze
29 – 38
18 – 24
16 – 20
8.0 – 10.7
2 – 3
6 – 9
Moderate waves of some length. Many white horses. Small amounts of spray.
Branches of a moderate size move. Small trees begin to sway.
6
Strong breeze
39 – 49
25 – 30
21 – 26
10.8 – 13.8
3 – 4
9 – 13
Long waves begin to form. White foam crests are very frequent. Some airborne spray is present.
Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic garbage cans tip over.
SMALL CRAFT ADVISORY
7
High wind, Moderate gale, Near gale
50 – 61
31 – 38
27 – 33
13.9 – 17.1
4 – 5.5
13 – 19
Sea heaps up. Some foam from breaking waves is blown into streaks along wind direction. Moderate amounts of airborne spray.
Whole trees in motion. Effort needed to walk against the wind. Swaying of skyscrapers may be felt, especially by people on upper floors.
SMALL CRAFT ADVISORY
8
Gale, Fresh gale
62 – 74
39 – 46
34 – 40
17.2 – 20.7
5.5 – 7.5
18 – 25
Moderately high waves with breaking crests forming spindrift. Well-marked streaks of foam are blown along wind direction. Considerable airborne spray.
Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded.
GALE
9
Strong gale
75 – 88
47 – 54
41 – 47
20.8 – 24.4
7 – 10
23 – 32
High waves whose crests sometimes roll over. Dense foam is blown along wind direction. Large amounts of airborne spray may begin to reduce visibility.
Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. Damage to circus tents and canopies.
GALE
10
Storm, Whole gale
89 – 102
55 – 63
48 – 55
24.5 – 28.4
9 – 12.5
29 – 41
Very high waves with overhanging crests. Large patches of foam from wave crests give the sea a white appearance. Considerable tumbling of waves with heavy impact. Large amounts of airborne spray reduce visibility.
Trees are broken off or uprooted, saplings bent and deformed. Poorly attached asphalt shingles and shingles in poor condition peel off roofs.
STORM
11
Violent storm
103 – 117
64 – 72
56 – 63
28.5 – 32.6
11.5 – 16
37 – 52
Exceptionally high waves. Very large patches of foam, driven before the wind, cover much of the sea surface. Very large amounts of airborne spray severely reduce visibility.
Widespread damage to vegetation. Many roofing surfaces are damaged; asphalt tiles that have curled up and/or fractured due to age may break away completely.
STORM
12
Hurricane-force
>= 118
>= 73
>= 64
>= 32.7
>= 14
>= 46
Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility.
Very widespread damage to vegetation. Some windows may break; mobile homes and poorly constructed sheds and barns are damaged. Debris may be hurled about.
HURRICANE
Beaufort Scale 3 is when "light flags [are] extended", and that means trouser legs flap a bit. From about 10 mph on up, the wind can be a factor on slick greens and long putts. At this speed, autumn leaves tumble across the green at about 10 feet every second, which is about the same as a person moving with a slow bouncy jogging. Around Scale 5 at 20-25 mph, long putts on slower greens and short putts on fast greens are a problem. At Scale 6 (25-30 mph), there is a light switching noise in tall grasses like seaoats and in the telephone wires. At Scale 7 (around 35 mph), walking into the wind is difficult. Above that, things start breaking apart, like tree branches and roof tiles.
The extension of the flag in the hole depends upon the heaviness of the flag material (size and density). Golf "wind speed flags" feature three weights that extend at 6, 12, and 18 mph winds:
Other flags mount on the golf cart so the player has a mobile reference for each shot when the cart is stationary. A "streamer" is a better indicator of wind direction than is a flag or even a windsock. A golfer can easily detect wind direction at the ground by seeing which way his trouser hems blow, and a little higher up by facing the direction that equalizes the sound of the wind into each ear. He also can toss a bit of grass.
A related method for learning wind speeds, used by the inventors of the golf wind speed flags, is to mount a golf flag of normal size and fabric on the front of the car or truck, and then drive at specific speeds where the driver can see exactly how it flutters and extends at various speeds likely to be encountered (e.g., 5 to 30 mph). This way, the golfer trains a skill at perceiving wind speed by simply looking at the pin. And the golfer can note wind speeds with an iPhone app and correlate that to the flapping of his pants legs, or the lateral drift of toss grassed before it hits the ground.
Fans in general can be used to learn different wind speeds.
270 Watt "Whole House" Fan (18"=46cm diameter)
The above graph plots wind speed 5 cm from the face of the fan at various locations out from the center. In general, the wind speed measured 7-8 mph. That wind speed will certainly blow your hair back from your face, but not much more than that. One model Philips hair dryer with four speed settings has air flow velocities of 12 m/s (27.4 mph), 10.5 m/s (24 mph), 8.2 m/s (18.7 mph), and 6 m/s (13.7 mph). The dryer automatically reduces temperature along with air flow in order to avoid tangling of hair during drying. Most dryers have only two dettings -- "high" and "low" -- and dryers generally have the same diameter fans or about the same. Testing the "high" setting on another hair dryer, then, is likely to indicate air velocity in the neighborhood of 20-30 mph and "low" will likely produce air velocity in the 15-20 mph range, and this is the point where wind starts to bother putting.
Large cooling fans (20" across or so) are sometimes located next to greens when the health of the grass is troubled by poor wind circulation for moisture evaporation and cooling, and so fans are generally located where the sunlight is especially direct or the local wind flow blocked or subsurface drainage not sufficient. Greenside fans typically blow at about 5 mph. This speed does not affect putting.
The real determiners of the maximum air flow of a dryer are motor wattage, fan diameter, and the distance the fan is located from the person, with high power being in the 1800-2000 watt range and low power in the 1200-1600 range (comparison chart). Testing a 1600-watt hair dryer with a 2-inch diameter fan on an aenometer, set on "low", and holding the hair dryer two feet away aimed directly at the wind cup when radially perpendicular to the wind stream, the air stream speed is about 20 miles per hour. Aim the dryer straight at the spindle axis of the aenometer and then shift it laterally the same distance as the radius of the air cups, still aiming the same direction.
If you want to "feel" different wind speeds on your face, aim a low-watt hair dryer at your face on "low" from about 24 inches away to feel a 20 mph or so wind, and then back the dryer farther away from your face to slow the wind down. At perhaps 30 or so inches away (as far as you can extend the arm and hand from the face) , the speed is reduced to about 10 mph.
Brenda Nave at NY Harbor, Sep 23 1966
(wife of Rod Nave, of GSU and HyperPhysics)
Looks like a 30 mph updraft to me!
Similar estimates of wind speed:
For a scale of wind speeds illustrated with photos, maps, and video clips from 5 mph tp 316 mph winds, go to this next page -- wind turbines exploding, hurricanes, tornadoes, powerkites, paragliding off Torrey Pines, inddor skydiving in Las Vegas at terminal velocity, wreck of the Edmund Fitzgerald, Texas Aeromotor windmill,
Measuring Wind Speed
The first way to "measure" wind speeds is to know how much your hair blows for a given wind speed. For example, a gentle breeze that lightly tosses forelocks or bangs is in the 5-10 mph range.
Another way is to walk on a calm day with a streamer of some sort and watch how it bends when you walk at a normal pace (about 30 inches each step and 2-3 steps or so per second and 18 inches per second for each mph, so 2 steps (60") per second is 3.5 mph and 3 steps (90") per second is 5 mph). When the wind later bends the same streamer up from vertical that same angle, the wind is the same as your walking velocity; when it bends double that angle, the wind is twice the walking pace, etc.
If you toss grass and watch how far laterally the wind takes it in 1 second, each 18 inches (1.5') is 1 mph of wind speed, or roughly 2 mph for each step away the grass travels. If autumn leaves are hopping by on the ground, you can see a 20-foot line along the direction the leaves blow and then watch for one second to see how far along this line the leaves get. This is like the traffic police who use two lines painted on the highway to time your vehicle speed. To see the start and end of the 20 foot line, simply face sde-on to the line the leaves follow from 20 feet off, aim straight at the line and then sweep your hand and arm 45 degrees along the line of the leaves. The 45 degree sweep marks out 20 feet, or whatever distance you stand from the line along the ground. Then watch a leaf cross the start point and count one second to see how far along the leaf makes it. Halfway is about 10 mph and all the way is 20 mph, etc. The wind speed is probably a bit more than that if the leaf starts and stops in the one-second trip. In general, if anything blows freely sideways and you can see the distance of travel over one second, just divide by 1.5' or 18" to find how many mph's the wind has (1 mph = 1.47 feet each second, rounded to 1.5 feet).
Unit of interest
1 mile/h = unit/sec
meters per 1 mi/h
0.45 meters/s
feet per 1 mi/h
1.47 ft/s
inches per 1 mi/h
17.68 in/s
steps per 1 mph
0.5 steps/s (each 1 step/s = 2 mph)
Unit of interest
1 km/h = unit/sec
meters per 1 km/h
0.28 meter/s
feet per 1 km/h
1.6 ft/s
inches per 1 km/h
19 in/s
According to John Hughes on PGA.com, "Speaking of winds, most all of Florida experiences a constant breeze. The breeze is dictated by offshore conditions on either side of the Lower Peninsula; the Atlantic Ocean or the Gulf of Mexico. Depending upon which body of water has the stronger wind currents, each golf course within the state can play completely different each day. You will probably notice PGA TOUR Professionals pick up loose blades of grass and toss them high in the air to watch how hard the winds carry the blades, as well as in which direction. This is a good indicator of the winds closest to the ground."
Scientific measurement.
US Signal Service Weather Instruments, Washington DC 1880
Click Print to Enlarge
DIY Anemometer (wind speed guage) -- something that rotates horizontally due to wind:
The anemometer records wind speed (AWS) as revolutions per second (rev/s), so using an anemometer is simply counting how many times in one second a particular wind cup spins around (1/2 a spin, 2 spins, etc., per second). Measure the radius (R) of the anemometer and multiply the circumference (2 x Pi x R) times the spin rate (AWS) to convert the spinning to conventional wind speed (WS).
The conversion of this radius (in inches) to wind speed in miles/h is:
(2 x Pi x R") in/rev x AWS rev/s / (12 in/ft x 1.47 ft/s / miles/h) = WS miles/h
The conversion of the radius in meters to meters/h is:
(2 x Pi x Rm) meter/rev x AWS rev/s / 0.447 meter/s / meters/h = WS meters/h
If you want to make your own aenometer, and would like the instrument to spin at a readable rate, solve the above equation by first picking AWS (1 spin or rev/s) and also pick the wind speed (e.g., WS = 20 mile/h), and solve for R:
R" in/rev = [(12 in/ft x 1.47 ft/s / miles/h) x 5 miles/h] / (2 x Pi x 1 rev/s)
This simplifies to:
R" in/rev = 353.6 / (62.84) = 5.6"
A radius that spins once in a 20 miles/h wind is 5.6" and the diameter is 5.6". A 10 miles/h aenometer is half thatradius or 2.8".
Pilots calculate the Headwind Component, Tailwind Component and Crosswind Component of any wind, if they do exist. Headwind and Tailwind are cosine functions of the wind while Crosswind Component is a sine function. Headwind and Tailwind do not occur together in normal conditions. Determining the ground speed of an aircraft requires the calculation of the head or tailwind.
Assume:
A=Angle of the wind from the direction of travel
WS=The measured total wind speed
CW=Crosswind
HW=Headwind
Then
CW=Sin(A)*WS
HW=Cos(A)*WS
For example if the wind is at 24015 that means the wind is currently from heading 240 degrees with a speed of 15 Knots and the aircraft is taking-off from runway 18; having heading of 180.
The aircraft is said to have 13 knots of crosswind and 7.5 knots of headwind. Aircraft usually have maximum headwind and crosswind components which they cannot exceed. If the wind is at eighty degrees or above it is said to be full-cross. Ifthe wind exceeds 100 degrees it is common practice to takeoff and land from the opposite side of the runway, it has a heading of 360 in the above mentioned example.
NB: This section is in progress. I'll bring to bear some specific calculations and testing to get some more exact effects.
A steady headwind
on a 20-foot putt can make the ball stop a foot or
more short on normal greens. Going downwind is not
that big a deal unless the break is very subtle, in
which case the wind can shove the ball a little thru
the break. But the tailwind doesn't influence the
ball all that much unless it is moving faster than
the ball, and this is usually only true for a small
segment at the end of the putt when the ball is slowing
down. Even then, the ball is settling back down into
the nap of the green, so the wind has a tougher time
changing the ball's roll unless the green is slick.
Crosswinds have a greater "push" effect
on the ball if the putt is long and the green is slick.
A straight 20-foot putt on a normal-speed green with
a 20-mph crosswind can see the ball get pushed quite
a few inches to the side by the end of the roll, and
this makes planning the ending break of the putt tougher.
On short putts on slick greens in stiff wind, don't
be shy and certainly don't "baby" the putts.
Winds that come and go are obviously more troublesome
than a steady wind. Wind that challenges balance can
be countered with a wider stance and a lower bend,
and perhaps with a more compact stroke as well (grip lower with tighter grip pressure).
Headwind and Distance. A 10 mph headwind is typically considered a one-club wind for irons, and a 20 mph headwind changes a 7-iron approach into a 5-iron approach (assuming the player hits each iron about 10 yards further) (see this Greg Norman explanation). For the driver, a 20-mph headwind will take 50 yards out of a 250-yard windless drive (20%), but most of that is due to the long time the ball is in the air (around 6-7 seconds). On the ground, a 20-foot putt takes around 3-4 seconds (half that of a drive), so putting into a 20-mph headwind with the force used on a windless day can be expected to make a 20-foot headwind putt perhaps as much a 10% short, or 2 feet short. So, the "rule of thumb" is 1 foot or 12" short for each 10 mph of headwind.
Downwind and Distance. Downwind would not have as great an effect.The same 20-mph tailwind for a 250-yard drive helps the ball along only an extra 20 yards, or 1 yard per 1 mph tailwind (8%). On the ground, that means 10" longer for each 10 mph of tailwind or aout 1" long for each 1 mph of wind or 10" for each 10 mph. The tailwind reduces the relative speed of ball-wind headed forward, so a 10 mph ball in steady air fights in effect a 10 mph counter wind, a 10 mph ball meeting a 10 mph headwind fights a 20 mph counter wind, but a 10 mph ball trailed by a 5 mph tailwind only fights a 5 mph counter wind.
Effect of Wind on Line and Break. Wind affects line and break as well as distance. According to Norman, a quartering wind that opposes a draw or a fade might also add one club on occasion. But in general he says that wind does not much affect straight shots. My experience is that once the wind gets above a minimal level, it does affect the line of straight putts left-right, and moreso when the putts are longer and over slicker green surfaces and rolling for longer total times. If the "tumbleweed trots across the green" in a strong steady wind, that might be a 40 mph wind or more, and putting a 20-foot putt on a Stimp 9-10 green in the N-S direction when the wind is E-W (right to left) can blow the ball to the left by as much as 1-2 feet by the time the ball reaches the cup. This is about as bad as conditions will get, since more wind than this is practically unplayable. Most steady winds in the 20-30 mph range will affect a straight putt like this about 6 inches left over 20 feet, so a useful rule of thumb is 0.25 feet or 3 inches for each 10 mph of sidewind for each 10 feet of putt. Downhill putts might be affected just a wee bit more than uphill putts, due to the longer total rolling time.
Downwind-then-headwind Breaks. Presumably this means in putting that if the startline heads downwind at the beginning and then breaks back into headwind for the final slow section of the roll, the wind effectively requires recognizing that the wind will make the ball "stay out" by breaking LESS than expected when putted with the usual windless speed. This effectively makes for shorter distance but also a little sharper break, stopping a bit high and short. The danger then is playing a windless break and the wind stopping the ball high and short, so the golfer should add more speed and perhaps play a little less break as well. The cure for leaving putts "high and short" is to play the ball "lower and longer".
Headwind-then-downwind Breaks. The opposite situation starts the ball off into a headwind and then the break takes the ball downwind towards the cup. The would appear at first to have the same "net effect" as the downwind-then-headwind putt, except that the ball is slower in the latter section, so the downwind has greater effect on the putt here. These putts played with windless line and direction tend to end up low and a little long. The cure for "low and long" is "higher and shorter" -- higher line and perhaps a bit less speed.
Straight Putts and Wind Effect on Line. Headwinds tend to blow the ball on straight putts a bit left or right of the line, since the wind has some directional fluctuations and since the wind exasperates the imperfections in the green that also knock the ball off line. Generally, typical modern greens knock putts off line about 1 degree, and on a 10-foot putt this means the accuracy of line can vary anywhere between 2 inches left and 2 inches right regardless of the golfer's accuracy of aim and stroke. Putting into a headwind makes this a bit worse, and putting uphill into a headwind makes this offline effect slightly greater. Downwinds tend to straighten out putts more than one should expect from the variance due to surface imperfections, at least when the wind is steady in direction and force.
"The Wind Ship of the Prairies: Fort Kearney, May 27, 1860. The prairie ship, which passed here last Saturday, is a very light built wagon, the body rounded in front, something in shape like a boat, to overcome the resistance of the air. The wheels are remarkably light, large and slender, and the whole vehicle strongly built. Two masts somewhat raked carry large square sails, rigged like a ship's. . . . In front is a large coach lamp, to travel by night when the wind is favorable. . . .The ship hove in sight about eight o'clock in the morning, with a fresh breeze from N.E. by E.; it was running down in a westerly direction for the fort, under full sail across the green prairie. The guard, astonished at such a novel sight, reported the matter to the officer on duty, and we all turned out to view the phenomenon."
For additional information and videos about winds in the solar system and in interstellar space, as well as a collection of wind music videos, visit this next page.
Ultimately, all our wind comes from the solar wind and the effect of the Sun (Helios) on temperatures and energy on Earth.
Tower of the Winds (Horologion of Andronicos), Agora, Athens
N:Boreas, NE:Kaikias, E:Apeliotes, SE:Euros, S:Notos, SW:Lips, W:Zephyros, NW:Skiron
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