What Causes Acoustic Sounds In The Sky ?

13 Apr 2018

We are all familiar with the sounds that thunder makes during a rainstorm. Does the atmosphere make other unusual sounds? Read on to learn about sounds in the sky.

Are people hearing the sounds of trumpets coming from the sky? What about strange humming sounds?  Is it just thunder? Scientists believe they have an explanation concerning this phenomena? Before we leap to space aliens sending signals to Earth, let’s learn more about what may cause the sounds in the sky.

Medieval Explanations

Just as we cannot see all light with the naked eye, we cannot hear all the sounds around us. For centuries people attributed the sounds of thunder to God’s displeasure with the Earth. Every lightning bolt hitting the Earth was a reprimand from the heavens. To keep bad weather from happening, churches decided that ringing bells would dissipate the storm. Bells were often inscribed with phrases such as “Fulgura flango” (or “I subdue the thunderbolt”). Unfortunately, the bell ringer would die from a lightning strike during a storm. Thankfully, Benjamin Franklin concluded this practice after his kite, key and lightning experiment proved that these events did not come from God’s judgment.

The Sounds of Thunder

Thunder is caused by the rapid heating (and then cooling) of the air from lightning. Lightning is exceptionally hot, so when it passes through the air, it heats the air very rapidly. This heat causes a rapid expansion of the air column followed immediately by rapid contraction of the air column due to the air cooling back down. This sends out a shockwave through the atmosphere, which results in the sound that we refer to as thunder. If the lightning hits close by, the thunder will sound like a crack or bang. If the thunder is caused by lightning that is far away, it will rumble and slowly fade away.

Credit: NASA

Earth’s Radio Emissions

According to Nasa, the Earth has ‘natural radio emissions.’

The Agency says: ‘If humans had radio antennas instead of ears, we would hear a remarkable symphony of strange noises coming from our planet. Scientists call them “tweaks,” “whistlers” and “sferics.”‘They sound like background music from a flamboyant science fiction film, but this is not science fiction. Earth’s natural radio emissions are real and, although we’re mostly unaware of them, they are around us all the time.’

Scientists have analyzed records of sounds and found that most lie within a range not audible to humans. What people hear is only a small fraction of the actual power of these sounds. In geophysics, they are called acoustic-gravity waves. These waves form in the upper atmosphere at the atmosphere-ionosphere boundary. What causes these waves? Earthquakes, volcanic eruptions, hurricanes, storms, tsunamis, have the potential to form these sounds.

Solar flares and the energy flow generated by them also can lead to these sounds. As the flares rush toward the Earth, it destabilizes the magnetosphere, ionosphere, and upper atmosphere. The impact of shock waves in the solar wind and bursts of electromagnetic radiation are often the leading causes of acoustic-gravitation waves during solar activity.

We now can rest easy at night knowing that the sounds in the atmosphere are not from a pending alien invasion. Scientists have provided a logical explanation to put our minds at ease. So if you hear what sounds like trumpets or humming in your backyard, realize that its just the Earth’s atmosphere is undergoing a change in energy.