This Is Not a Shockwave

this is not a sonic boom but a quick search of google images will tell you otherwise image after image after image all showing something that is not a sonic boom so if this is not a sonic boom what is it to answer that question we first need to address what a sonic boom is shock waves occur as a result of the maximum speed of sound which is the speed pressure waves can travel which we perceive as sound the speed of sound in air is around 340 meters per second but that does change with atmospheric conditions primarily temperature so let's imagine a stationary object it releases a sound wave periodically which propagates out at 340 meters per second these sound waves are just areas of high pressure air traveling outwards now when the object starts to accelerate we can see that the distance between the sound waves behind the object increases and the distance between the sound waves in front of the object decreases the pressure waves can't travel any faster than 340 meters per second and the object is catching up with them and when it does catch up with them something weird happens the sound waves begin to stack up on each other causing a sudden spike in pressure this pressure wave is incredibly thin it's just a thin band of molecules colliding because they can't get out of each other's way fast enough only 100 to 200 nanometers wide the human eye can't see this under normal conditions but that high pressure air does distort light through refraction and with the right tools we can use that to visualize shock waves using schlarin imaging and shadow graphs here you can see the sound wave propagating out of the gun when it's fired then the bullet traveling faster than the speed of sound bursts from the gun and catches up with the sound wave while forming its own conical shock wave this is the only way we can see a shock wave directly through light distortion so if this is not a shock wave what is it what we are seeing here is water condensing in the air because of a temperature drop water vapor in the air is typically invisible we can only see water vapor when the air is too saturated with water to absorb any more we can achieve this by increasing the water content in the air like when we boil water and we can see the water vapor rising from it or by decreasing the temperature of the air warmer air is capable of holding more moisture so if we were at 100 absolute humidity the maximum amount of water the air can hold at 30 degrees there would be about 30 grams of water vapor per meter cubed of air but if we drop the air temperature to zero degrees celsius the maximum amount of water vapor that air could hold would be only 5 grams per meter cubed when the air temperature drops like this water is forced to come out of the air and form visible water vapor like clouds or these vapor cones that's what we're seeing here a sudden drop in temperature that forces water out of the air but shock waves cause a spike in pressure increases in pressure cause an increase in temperature not a decrease and that's really why we aren't seeing a shockwave we are seeing the exact opposite of a shockwave we are seeing an expansion fan expansion fans occur when supersonic flow travels over an area where the flow is given space to expand in particular convex corners like over the convex curve of the canopy or after the thickest part of the wing and that's exactly where we see vapor cones form on all of these videos my favorite example of this is this video of the discovery space shuttle launching on july 13 1995 carrying a communication satellite to orbit we can see vapor cones as the air travels over the convex corners of the solid rocket booster and the shuttle's flight deck in videos like this one of the fa18 the vapor cone flickers in and out of intensity as it travels through areas of higher and lower humidity that's why we don't always see a vapor cone we can only see it in the right conditions where that expansion of air causes a high enough decrease in temperature to force water out of solution so we aren't seeing a shock wave here we are seeing the exact opposite an expansion fan of course we can see condensation like this occur well below supersonic speeds like when high angle of attack maneuvers cause rapid expansions of air behind the wing but there is a kind of shock wave we can see a shock wave that occurs when something travels faster than the speed of light many of you will be looking at the screen with a raised eyebrow right now but what you are looking at right now are shock waves of light caused by electrons traveling faster than light in water in the extended cut of this video available exclusively on nebula i have included an explanation of how exactly this happens and the phenomenons uses in engineering if you are a fan of this channel nebula is the best place to watch everything we make when possible we upload our videos early to nebula all advertisements are cut from the nebula versions of my videos and 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Channel: Real Engineering

Views: 586,534

Keywords: engineering, science, technology, education, history, real

Id: uO4FckCAZtU

Length: 7min 19sec (439 seconds)

Published: Sat Aug 28 2021