Thursday, March 5, 2009

The Science of Baseball

Ah, it is nearly Spring, and springtime means baseball! The pros are at their spring training camps in the warmer parts of the United States like Florida and Arizona. And, 300+ youths in our fair city are at Los Arboles and Preston parks swinging away with at least as much enthusiasm if not more.

Scientists love baseball. I cannot explain exactly why this is. But, this is a sport that unites geeks and jocks from coast to coast. And, in fact, the President of our city's Pony Baseball and Softball league is a geek-jock himself, scientist by day, baseball empresario by night, weekend, and most school holidays from December to July (that’d be Mr. Dr. SwimsWithFishes again).

Perhaps this is because baseball, unlike life, conforms so well to the laws of physics, where things are predictable, orderly, and behave utterly sensibly. Now, this does not mean baseball players and umpires behave so sensibly. But, ball, interacting with bat, behaves quite predictably. You can calculate, quite reliably, exactly how to hit a ball so that you will get a home run every time at bat. You can draw it on paper; determine forces, angles, and trajectories; form and solve the equations.

The sport comes in figuring out how to get a pitcher to pitch that ball to you, and how to get your body to hit that ball, just like on paper. It is the interaction between the players, and trying to figure out how to achieve a known outcome, that drives our passion for the sport. This interaction is like a dance. Even as spectators, we watch the dance with the same anxiety and emotion, fear and adrenaline as we felt back in the age of innocence at our first school dance and the boy/girl of our dreams was watching us from across the room (and all we hoped for then was that we might get to ‘first base’ with Dream Boy/Girl).

The science of a baseball home run is all in the angles. Line drives, that travel with no arc, no change in height off the ground as they leave the bat, are darn fast, but they don’t travel far. This is because of our old constant friend, gravity. The ball leaves the bat with some inertia, or some force, imparted by the swing of the bat. The magnitude of that inertial force depends on how hard the bat hits the ball. Harder hits impart greater velocities and therefore greater inertia. But, the ball is experiencing friction as it travels through the air. As it slows, eventually the force of gravity, pulling the ball down, will be larger than the inertial force and the ball will begin to fall.

Now imagine the ball is hit with the same speed but with a slight upward arc. At the time when inertial forces begin to weaken, and gravitational forces start to take over, the ball will be higher in the sky. The increased distance to the ground, and the trajectory of the arc, ensure that the ball travels farther before actually contacting the ground. Intuitively, we know this. Line drives rarely hit the home run fence. Home runs are big arcing hits that soar into the grandstands.

It is actually more difficult to hit a ball fast with an upward trajectory than with a straight one. Line drives are fast and pitchers hit with these balls get hurt, badly. However, even if the force imparted onto the ball is lower, a sufficient arc will take the ball farther. A little arc goes a long way, and you can get too much of a good thing. Obviously, a ball hit straight up goes nowhere at all except up. The science is in finding the just right arc. In baseball, as in life.

Which Way the Wind Blows

With the Wind Festival right around the corner, I thought it was a fine time to talk about the science behind how and why the fair city in which I live is so darn windy. Most of the cities in our region have a token produce item that they celebrate annually. But, what makes our city unique? It is the wind, no doubt. I love that we have a festival dedicated to that oceanographic feature that so defines our fair city.

That’s right, I called the wind an oceanographic feature, and it is not just that I am a marine scientist that makes me view the wind in this way.

Wind is formed by a pretty basic principle - hot air rises. When hot air rises, the cooler air rushes in to take its place, and viola, you’ve got wind. That basic principle explains global wind patterns, as the air is warmer at the equator than at the poles, and local wind patterns, such as the off-shore winds that surfers use to predict how good the surf will be. The ocean is a strong factor in determining which way the wind blows, as ocean temperatures drive the giant conveyor belt of air that winds its way around the globe, interrupted by the land masses that form a mere 30% of the earth’s surface.

Spring, Wind Festival time, is probably the consistently windiest time of year here. This is because the ocean off our coast is at its coolest temperature, thanks to spring upwelling. Upwelling is the movement of cool deep waters up to the ocean surface. They are brought to the surface because of global winds, winds blowing towards the equator. Air at the equator is hot and rising, cooler polar air masses are moving in to replace it. As these winds blow down past our coast, the rotation of the earth causes the surface water to be pulled by the winds the to west, or out to sea. As the surface water is pulled away from our coast, the cool deeper water rises up to take its place. Thusly, as any surfer knows, the water off our coast is the coldest in the spring.

Cooler ocean temperatures mean cooler air temperatures sitting on top of that water. As the inland air gets warmer and rises, the cool coastal air is sucked inland to replace it. This temperature differential is probably the greatest in the spring, and particularly in the afternoon in the spring. That means lots of wind.

Land heats and cools faster than the ocean. The ocean actually changes temperature by only a few degrees. This means we typically get offshore winds when the inland areas are cool, like in winter (off shore winds are good for surf, along with big swells brought by winter storms generated far away). We get on-shore winds when the inland areas are warm, such as during the upwelling periods described above. We might get on-shore and offshore winds in the same day depending on the temperature change inland. In our city, we know this well, as we spend our summers watching the fog “burn off” in the late morning and get pushed out to sea (as the heat reduces the moisture content in the air), only to get sucked back on land in the late afternoon.