FARGO — As the air becomes cooler in the fall, we see many changes in the environment that signal the change of season. Some of these changes are more visible than others. A subtle change concerns the way sound travels through the air. The cooler, drier air of fall is also denser than warm, humid air, providing a more efficient medium for sound waves to travel. In autumn, we hear sounds a little better.

Temperature inversions, more frequent and more pronounced in fall, are another reason for better sound. When the ground cools at night, the air near the ground is also cooled, often becoming colder than the air directly above it. This layer can be 100 to a few hundred feet thick. The top of this layer is called the boundary layer and can reflect sound waves back to the ground, allowing sound waves to travel greater distances.

John Wheeler is chief meteorologist for WDAY, a position he has held since May 1985. Wheeler grew up in the South, in Louisiana and Alabama, and cites his family’s move to the Midwest as being important in developing his fascination with weather and climate. Wheeler lived in Wisconsin and Iowa when he was a teenager. He attended Iowa State University and graduated with a bachelor’s degree in meteorology in 1984. Wheeler worked about a year at WOI-TV in central Iowa before moving to Fargo and WDAY.