Windswept_ The Story of Wind and Weather - Marq de Villiers [56]
As you might expect, the name is derived from the casino at Monte Carlo. Like scientists trying to model the real world on computers, gamblers too are faced with large sets of apparently random numbers. Each gambler, notoriously, has his or her own method of assessing the odds. In the casino as in the humdrum world beyond its walls, the numbers may be random, but very large sets of runs will provide statistical patterns that are more or less valid—as chaos theory would predict. To take the most widely known example, it is impossible to predict whether a coin toss will come up heads or tails, but a very large number of such tosses will always yield a fifty-fifty ratio of heads to tails. The Monte Carlo simulation, then, is simply a use of random numbers and probability statistics to investigate problems. It makes possible the examination of problems otherwise too complex for computation. For example, solving equations that describe the interactions between two atoms is fairly simple; solving the same equations for hundreds of thousands of atoms is impossible. Monte Carlo allows the sampling of such large systems, and the wind climate around bridges is a real-world example. (MC methods are used everywhere in science, in disciplines as diverse as economics and nuclear physics.)45
An intriguing test case for local wind studies was something not nearly as, well, dire, as the winds that destroyed trains in Newfoundland or the bridge near Tacoma. It was a wind that affected, and still affects, only the pocketbooks of a handful of very wealthy men. These are the winds around the eleventh green and twelfth tee of Augusta National Golf Course, the home of the Masters tournament in Augusta, Georgia. Golfers have ruefully called this Amen Corner, in recognition that only prayer seems to help the ball go where it is directed. Notoriously gusty winds from the left can be in the face of a golfer teeing off at the twelfth, but at the twelfth green, the target of the current shot, the flag shows wind coming from the right. How, then, to judge the shot? If you aim the ball to match the wind in your face, halfway through its flight it will abruptly be seized by a contrary wind and blown deep into the rough. If you compensate for that, you might still lose. The gustiness of the site means that the compensating wind late in the shot may not be there, dragging the ball into the rough on the other side. Tournaments have been won and lost at Amen Corner, which means substantial money is at stake.
Amen Corner is at the bottom of a slender valley between two hills. Tall trees surround the twelfth tee and green, in contrast with the relatively exposed eleventh green. For years, golfers have blamed those trees for causing the wildly eccentric wind directions at the three locations of prime interest: the twelfth tee and green and eleventh green.
In 2002 the Augusta National placed a call to Alan Davenport. His Boundary Layer wind tunnel researchers had never done a golf course before. It was hard to resist, so they took the commission.
The first trick was to construct a model of Amen Corner they could use in the lab. From topological maps, photographs, and sketches, they put together a 1:200 model made of high-density foam. Fairways were made of drywall compound; more than six hundred trees were constructed with sponge branches and wire-and-foam trunks; Rae's Creek was acrylic over a foam base, with sil-icone to replicate wind-induced wavelets. Tiny people were added for scale. Stage two was to model the surface wind speeds and directions. Data were available from a nearby airport dating back to 1949; from the raw data they extrapolated seasonal and annual frequency histograms corrected to the standard meteorological height of thirty-three feet. From this, wind speed and direction probability distributions were plotted for the full year and the month of April, when the Masters is played.
The next step was to plot the trajectory of a ball. They chose