(WKBN) – Peak summer heating has arrived in northeast Ohio and western Pennsylvania, which provides plenty of energy for thunderstorm activity at all times of night.
Many of you probably enjoy weekend mornings with thunderstorms that produce a slow roll of thunder that help you sleep in. However, did you know that the sound produced by lightning sounds different at different times of day?
How is the sound of thunder created?
Sound is created when an object vibrates, which, in turn, vibrates the surrounding air molecules. In the case of lightning, the electrical channel heats the air around it to a temperature upward of 50,000 degrees Fahrenheit (five times hotter than the surface of the sun). This intense heat causes the air to rapidly expand, which excites the air molecules and creates thunder.
How does temperature affect the sound of thunder?
The speed at which sound waves travel is dependent on the type of medium (air, water, etc.) and the temperature of that medium. This means that the sound of thunder can travel at different speeds in different parts of the atmosphere.
First, consider a scenario where a thunderstorm forms on a hot, summer afternoon in the Valley. In this case, the temperature is warmest at the surface of the Earth, and it cools with increasing elevation. This is a normal temperature profile that sets up throughout the day.
When lightning occurs in this scenario, the thunder soundwaves move faster near the surface of the Earth and slower at higher elevations. This causes the sound waves to bend upward and move uniformly away from the lightning strike.
Why is the sound of thunder louder in the morning?
Next, consider a special case where a thunderstorm forms during the early-morning hours. In this case, the surface of the Earth is cooler than the air just a few hundred feet above it. This is due to the loss of solar heating from the sun.
Thus, in this case, there is a warm layer of air a few hundred feet above the surface of the Earth that is trapped between a cool layer at the surface and a colder layer above it. This scenario is called a temperature inversion.
In this case, the thunder soundwaves produced by a lightning strike travel slower near the surface of the Earth and faster in the warm layer right about it. This causes the sound wave to bounce off of the warm temperature layer, which is a scientific term called “refraction.”
The refraction acts to amplify the soundwave, which enhances the sound. Additionally, the cooler air at the surface causes the sound of thunder to last longer. Thus, the temperature inversion causes the sound of thunder to be louder and last longer.
