Early Wednesday morning, those in South Trinidad reported hearing loud thunder, but there were no thunderstorms directly over the island. A relatively distant thunderstorm was occurring south of the island in the Columbus Channel, but the thunder was as loud as if it occurred overhead.
While it sounds like science fiction – thunder from apparently nowhere – it all has to do with physics.
Thunderstorms that develop when temperatures near the surface are relatively cooler than the air above can result in louder, longer-lasting thunder than those in warmer weather.
This occurs because of how sound travels in colder conditions and something called a temperature inversion, or when a layer of warmer air is above a layer of cooler air near the surface.
When this happens, thunderstorms can develop in chillier conditions because the layer of warmer air aloft provides enough energy for thunderstorm development. These thunderstorms are often called elevated thunderstorms.
This warmer layer also can influence how thunder sounds. Thunder in warmer weather generally dissipates in all directions. However, when the air is cold at the surface, the warmer air higher in the atmosphere acts almost like a ceiling, trapping the sound and then refracting it back toward the ground.
This refraction can amplify the sound of thunder. It can also make the sound linger. Sound waves also move slower in cold air and faster in warmer air, amplifying these sound effects.
On Tuesday night, an atmospheric sounding (a vertical profile of the atmosphere) recorded temperatures of 26.9°C at the surface (12 meters altitude), cooling to 18.5°C at 1,340 meters. However, between 1,340 meters to 1,557 meters, temperatures warmed slightly to 19.5°C.
This small temperature inversion was sufficient to refract the sound of thunder back to Earth.
Showers and thunderstorms are affecting Trinidad and Tobago associated with the Intertropical Convergence Zone. Based on research, the ITCZ in the Tropical Atlantic has its strongest activity occurring between 12:00 AM and 6:00 AM local time, with another peak during the Northern Hemisphere summer months between 12:00 PM to 3:00 PM.