The science behind the sound: The thunder of artillery guns explained

Article / February 9, 2018 / Project number: 17-0019

By Major Craig Cutting, The Royal Regiment of Canadian Artillery School

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Gagetown, New Brunswick — For anyone, including those residents of the communities surrounding 5th Canadian Division Support Base Gagetown (5 CDSB) who are curious as to why they hear the awe-inspiring thunder of Howitzers differently on any given day, the intent of this article is to explain both the scientific and training requirements of the “how” and the “why” Guns are heard in good weather and in bad, during the day and night.

It is the ardent hope of the author that the reader will emerge with an understanding of why the volume and propagation of sound from the Guns, even when firing from similar locations, can significantly fluctuate based on several factors that will be described herein.

Atmospheric effects on sound

First, to address the scientific aspects of “how” Guns are heard, it must be understood that atmospheric effects, comprised of four major factors: wind, temperature, humidity and cloud cover, will have a large impact on sound. These four major factors will now be discussed in order, with a practical example provided at the end.


The first factor is wind, which alters sound propagation by ‘bending’ the sound wave. At lower elevations, wind travels more slowly due to terrain features such as hills, trees, etc. At higher elevations, wind travels faster as it is unimpeded. Therefore, if you are downwind from a source, you will hear louder noise levels than someone standing upwind.


The next factor is temperature gradients in the atmosphere. On a hot day, the air is warmest near the ground and decreases in temperature at higher altitudes, which causes sound waves to refract upward, away from the ground. On a cold day, this temperature gradient will reverse, having the opposite effect. Therefore, at night when it is cooler, a listener will experience raised noise levels compared to midday when it is much warmer.


The third factor is humidity, which also has an impact on sound wave propagation. As the humidity increases, so too does the percentage of water molecules in the air. Because water molecules have less mass than nitrogen and oxygen, the air becomes less dense allowing sound to travel faster. Therefore, a relative humidity increase will result in a raised noise level at the listener’s location.

Cloud cover

The final factor is cloud cover, a constant feature in the Maritimes. On as clear day, sound waves will propagate into the atmosphere and eventually dissipate. However, on a cloudy day, the sound waves will be redirected off of the clouds back to the ground and will therefore result in a raised noise level at the listener’s location.

In the spring, an example of the aforementioned factors would be on a cool, cloudy, humid evening, the Guns firing will be heard from much farther away, especially if downwind, than upwind from Guns firing on a dry, hot, clear afternoon.

The “why” of the noise barrage is two-fold

As for the “why” Guns are heard, The Royal Regiment of Canadian Artillery School, located within 5 CDSB, exists to provide the Canadian Army with combat-capable soldiers and officers ready to meet the operational and domestic requirements of the Canadian Armed Forces in service to the Government of Canada.

To provide world-class training, the practical impact is that Guns fire by day and night, in all weather conditions, to prepare Canadians to fight and win within a challenging modern battlefield.

Hopefully this article provides some illumination as to the god-like thunder wielded by The Kings of Battle. While this noise may be initially disconcerting to some, know that it is the sound of the Canadian Armed Forces training to stand on guard for our great nation.


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