2 definitions by Tornadopelt
Typically, when air is displaced by a pressure wave, it moves at the speed of sound. These pressure waves can be generated from one's vocal cords (when speaking), the vibration of an object, or the impact of one object against another. However, in certain cases, the pressure wave is generated by a collision between air parcels, such as when lightning heats the air immediately around it. This rapidly-expanding air crashes into the cooler air around it, generating a massive spike in pressure followed by a sharp drop-off. It is this sharp spike and drop-off combination that differentiates a sound wave and a shock wave. Shock waves can be either naturally generated, in the case of volcanic eruptions, lightning strikes, and asteroid impacts; however, they can also be generated through man-made means, such as explosives that derive their power either from chemical energy that is converted into thermal energy or by way of nuclear fission or fusion. If the pressure differential occurs in air where clouds can condense, the act of high pressure passing through the area and low pressure following can cause temporary "Wilson clouds" to form.
The shock wave generated by the explosion in Beirut generated Wilson ring clouds and severely damaged the city of Lebanon.
by Tornadopelt May 17, 2022
The part of the human body that tightens and moves down to create lower air pressure in the lungs than in the outside environment, allowing air to move into the lungs. This part then relaxes and moves back up, generating higher air pressure in the lungs than the outside environment, forcing carbon dioxide out of the lungs. This part also separates the chest cavity (cardiovasuclar and respiratory) from the abdominal cavity (digestive system), which is why your chest expands as you breathe. Also that fancy part of an air horn that rapidly vibrates in response to air movement, generating that screeching sound.
(From Business Insider) "When you take a breath in, your diaphragm tightens and is pulled down to allow your lungs to expand. When you exhale, your diaphragm relaxes and is pushed back up to expel the air from your lungs."
by Tornadopelt March 14, 2019