Why do baseballs travel farther in warm weather than in cold weather?

Welcome to our "Science of Baseball and Fitness" series! In these articles, we explore how science affects sports. We explain interesting facts about baseball and how our bodies work during exercise. Today, we'll discover why baseballs fly farther on hot summer days than on chilly spring afternoons.

The Air Around the Ball

When a batter hits a baseball, the ball must push through air as it flies. This pushing is called air resistance or drag. Air resistance slows the ball down.

In warm weather, air molecules spread out more. They have more energy and move around faster, which creates more space between them. This makes warm air less dense. Less dense means there are fewer air molecules in the same amount of space.

When air is less dense, the baseball has fewer air molecules to push through. This means less resistance, allowing the ball to travel farther!

A Simple Example

Imagine walking through a swimming pool versus walking through an empty room. The water in the pool makes it harder to move quickly because it's denser than air. Now imagine the pool water getting thinner and more like air. You could move much faster, right? That's similar to what happens to a baseball moving through warm air versus cold air.

The Baseball Itself Changes

Baseballs are made of materials that change with temperature too. Inside a baseball is a cork center surrounded by tightly wound yarn and covered with leather.

In warm weather:

• The materials inside the ball become more elastic (stretchy)
• When the bat hits the ball, more energy transfers to the ball
• The ball bounces off the bat with more speed

In cold weather:

• The baseball becomes more stiff
• The ball doesn't compress as much when hit
• Less energy transfers from the bat to the ball

The Bounce Factor

Scientists use something called the "coefficient of restitution" to measure how bouncy a ball is. Don't worry about the big words - it just means how much bounce a ball has!

A warmer baseball has a higher coefficient of restitution. This means it bounces better off the bat. A better bounce equals more distance.

How Big Is The Difference?

For every 10-degree increase in temperature (Fahrenheit), a well-hit baseball might travel about 3-4 feet farther. That might not sound like much, but it can be the difference between a caught fly ball and a home run!

A ball hit on a 90-degree summer day might travel 20-25 feet farther than the same hit on a 50-degree spring day.

What Players Do About It

Players know about these effects. In cold weather, batters might:

• Swing harder to generate more power
• Keep baseballs warm when possible
• Expect that the ball won't travel as far

Pitchers might enjoy cold weather because batters have a harder time hitting home runs.

Conclusion

Baseball is full of science! The next time you watch a game on a hot day and see lots of home runs, or notice fewer homers on a cold day, you'll know why. Temperature affects both the air the ball travels through and the ball itself, making baseball a different game depending on the weather.