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I am from India, and now its monsoon season. Typically, during this time, the sky is filled with dark rain clouds. Me, along with several of my friends, have observed from childhood that the planes that pass above us tend to sound louder when they pass through these clouds. It was such a routine observation for us, that it seemed obvious and natural to assume everyone else in the world would also have noticed the same. I can produce video evidence, if necessary, but that comes with an extra challenge of shooting in the rain.

But in short, the sound of plane becomes louder and sometimes more bassier, when the plane goes inside a dark cloud. I know it gets louder, because since the sky is not fully covered with clouds, there are intervals when the plane occasionally passes through windows of clear sky in between the clouds, and then you can clearly see (hear) the sound going back to normal. It sounds somewhat like a never-ending rumble of a distant thunder.

What might be the cause of this phenomenon? Normally I would expect the clouds to block the sound, but here it seems to amplify it.

Since sound reaching your ears depend on both the intensity of the sound source and the transmission quality of the medium,

  1. either the engine actually becomes louder (which I intuitively feel is unlikely, because to create such a loud sound would require huge engine power), or
  2. the air with clouds have better transmission, or maybe
  3. the clouds form an echo chamber amplifying the noise

Which of (one) of these could actually be the reason behind this observation?

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    $\begingroup$ i think this might have somehting to do with air pressure, and airplanes flying lower either due to lower pressure or because they are trying to avoid the clouds. However "cloudy" is not very well defined, since many different types of clouds form in different layers of the atmosphere for different reasons, and all of these could have an impact on airplanes. $\endgroup$
    – paulina
    Commented Sep 4 at 9:25
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    $\begingroup$ If it is a "fairly common observation", please cite some links. Such a claim should be substantiated with experimental observation. $\endgroup$
    – naturallyInconsistent
    Commented Sep 4 at 9:27
  • $\begingroup$ A video (with sound) would certainly help. Does the perceived loudness increase only happen when an airplane flying horizontally leaves blue sky to enter a cloud, or also when a climbing airplane enters a solid overcast cloud layer from below, or both? Does it happen for all types of clouds? You mention you'd need to shoot any video in the rain; does this mean the effect does not happen when there are clouds in the sky but it is not raining? Does it happen for all types of aircraft, e.g. from small private propeller driven planes to big passenger jets? $\endgroup$
    – David Bailey
    Commented Sep 8 at 0:50

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I will assume the airplane is below the clouds in your question.

Apparently the main effect of clouds on the sound of an airplane is due to reflections of sound waves. They reflect on the clouds above and are bent in the direction of the ground. Wind is also a relevant effect, as it biases the sound volume towards its flow.

For references on this and other variables that have effect on airplane noises, read

https://www.torontopearson.com/en/community/noise-management/understanding-airport-noise/environmental-perception-factors

and

https://www.tampaairport.com/business/airport-operations/noise-abatement/tips-homeowners/effects-weather-noise

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  • $\begingroup$ The OP did not specify if the aeroplanes are flying above or below the clouds. If they are flying above the clouds, the water in the clouds are already not going to fly into engines. $\endgroup$
    – naturallyInconsistent
    Commented Sep 4 at 9:47
  • $\begingroup$ Yeah, it was not clear, I just supposed it was below because when it is above you barely hear it anyway, both because in cruising the engines are on low power, and because the clouds reflect the sound. But you are right, the question is ill posed. $\endgroup$
    – Franklin Luis
    Commented Sep 4 at 9:56
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See sound refraction says that the atmosphere during cloudy weather is lower towards the ground and hotter towards up, so more sound then usual get reflected back towards the ground not dispersing upwards.

Also there is no way that a plane is louder as almost all planes make the same noise.

also presence of clouds can cause humidity that results in good quality of sound in these type of weather.

while about the echo, the clouds can perform echo but they are not solid so their echo does not affect much on the actual sound.

Thank you

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