Photo of Bluebell Woods in Sussex Photo of Bluebell Woods in Sussex

Sounds during a temperature inversion

Animal and road noise travels further during a temperature inversion

Normally, air gets cooler with altitude and this is what we expect to experience. We see snow at the tops of mountains, but none in the valleys. During a temperature inversion, warmer air sits on top of cooler air, creating a sandwich of cold air near the ground.

Sounds get trapped in this sandwich layer, meaning we get to hear things that we can’t normally. In these videos we can hear the normal nearby sounds (dogs stepping on leaves), but also distant birds and roads that can’t normally be heard.

Road noise travels much further during a temperature inversion

And it is not just sounds, temperature inversions also trap smells.

An excerpt from The Walker’s Guide to Outdoor Clues and Signs / The Lost Art of Reading Nature’s Signs (US) book:

“If you can smell smoke in the air on a cold morning, it is likely that there is a temperature inversion, which occurs when a layer of warmer air traps a cooler layer near the surface. The smoke from factories and home fires gets trapped near the ground and spreads along under the warmer layer, giving the air a musty whiff of smoke.

When there is a temperature inversion it creates a ‘sandwich effect’ and sound, light and radio waves get bounced between the top of the cool lower layer of air and the ground.

Sounds travel further in these conditions and can be heard more loudly, so you will hear airports, roads or trains that you cannot normally. The effects can be more dramatic if there are any very loud noises nearby and a violent demonstration of this effect took place in the middle of the last century.

An explosion creates an extreme form of sound, called a shock wave. In 1955 one of the earliest nuclear weapon tests in Russia created a shock wave that bounced back down off the inversion layer, knocked over a building in Semipalatinsk and killed the three occupants.”

A distant road can be heard when it normally cannot. The bright dot is the morning star, Venus.

See The Walker’s Guide to Outdoor Clues and Signs / The Lost Art of Reading Nature’s Signs (US) book for more info.