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I think it is more to do with air molecules under a large force, the force of the air being moved at great speed as the plane moves them whilst going supersonic.
A sonic boom is the thunder-like noise a person on the ground hears when an aircraft flies overhead faster than the speed of sound—supersonic.Air reacts like a fluid to supersonic objects. As the aircraft travels through the air, the air molecules are pushed aside with great force and this forms a shock wave much like a boat creates a bow wave. The bigger and heavier the aircraft, the more air it displaces.On the sea, there are small ripples in the water. As a boat slowly passes through the ripples, they spread out ahead of the boat. As the boat moves faster, it breaks through the ripples more quickly, forming waves. If it goes fast enough, the waves can't spread out fast enough, and they form a wake. It is formed out of all the little waves that would have spread out ahead of the boat, but couldn't, because of the boat's speed.When a plane travels through the air, it produces sound waves. Sound waves are not visible. If the plane is traveling slower then the speed of sound, then sound waves can spread out ahead of the plane. If it breaks the sound barrier and flies faster than the speed of sound, it produces a sonic boom when it flies past. All the sound waves that would have normally spread out ahead of the plane are combined together, and boom sound is produced.Boats moving rapidly through water create bow waves.When you're on the shore of the ocean and a boat zooms past, at first there is no disturbance in the water, but shortly after, a large wave from the wake crashes up to the shore. When a plane flies past at supersonic speeds, the same thing happens. Instead of the large wake wave, you'll hear a sonic boom.When planes fly through the air at moderate speeds, the air molecules have time to move aside to let the plane through. If the aircraft goes too fast, though, the molecules can't move aside, and the plane slams into them-boom!
"Air, even under pressure, is transparent - to see something, you need impurities in the air."Does water, always a constituent of air, count as an impurity? It's frequently visible.
"Water, in its gaseous form, as far as I am aware is never visible in air "So? What's wrong with fog or clouds?My money would be on the liquid form rather than ice.
YAY! [] look at that time stamp - DEFINITELY BED TIME..... this is eeeeerie
I'm an early bird ...... 10pm is usually tops as I read for a good hour and then get up at the crack of dawn.... The time stamp just threw me because of the near 22:22:22 nighty night []
At transonic speeds intense low-pressure areas form at various points around an aircraft. If conditions are right (i.e. high humidity) visible clouds will form in these low-pressure areas as shown in the illustration; these are called Prandtl-Glauert singularities. These clouds remain with the aircraft as it travels. It is not necessary for the aircraft as a whole to reach supersonic speeds for these clouds to form.
The Prandtl-Glauert singularity (sometimes referred to as a "vapor cone"), is the point at which a sudden drop in air pressure occurs, and is generally accepted as the cause of the visible condensation cloud that often surrounds an aircraft travelling at transonic speeds, though there remains some debate. It is an example of a mathematical singularity in aerodynamics.One view of this phenomenon is that it exhibits the effect of compressibility and the so-called "N-wave". The N-wave is the time variant pressure profile seen by a static observer as a sonic compression wave passes. The overall three-dimensional shock wave is in the form of a cone with its apex at the supersonic aircraft. This wave follows the aircraft. The pressure profile of the wave is composed of a leading compression component (the initial upward stroke of the "N"), followed by a pressure descent forming a rarefaction of the air (the downward diagonal of the "N"), followed by a return to the normal ambient pressure (the final upward stroke of the "N"). The rarefaction may be thought of as the "rebounding" of the compression due to inertial effects.These condensation clouds, also known as "shock-collars" or "shock eggs," are frequently seen during space shuttle launches around 25 to 33 seconds after launch when the vehicle passes through the area of maximum dynamic air pressure, or max Q. These effects are also visible in archival footage of some nuclear tests. The condensation marks the approximate location of the shock wave.Since heat does not leave the affected air mass, this change of pressure is adiabatic, with an associated change of temperature. In humid air, the drop in temperature in the most rarefied portion of the shock wave (close to the aircraft) can bring the air temperature below its dew point, at which moisture condenses to form a visible cloud of microscopic water droplets. Since the pressure effect of the wave is reduced by its expansion (the same pressure effect is spread over a larger radius), the vapor effect also has a limited radius. Such vapor can also be seen in low pressure regions during high–g subsonic maneuvers in humid conditions.Prandtl-Glauert singularity effects can be readily observed on a humid day by successfully cracking a whip. A visible cloud is produced at the point where the tip of the whip goes transonic.Notes1. It is important to recognize that the pressure profile rise-drop-rise is only figuratively described by an "N" and, indeed, it is better described as a "stylized-N" since the profile takes place within an ambient pressure context with pressure starting from, and returning to, the same ambient point afterward. Therefore, the "free-tips" on the end of the "N", relative to the centre of the diagonal do not begin as low, nor end as high, as is implied by the normal shape of the letter N.
As I rather suspected, it is more due to low pressure than to high pressure, but otherwise you are about correct.Quote no way! Ok, not wishing to go against the guys and gals at wiki. But, could there haue been a high pressure system and one of the actions of the planes speed was or is to cause a localised low pressure?
no way! Ok, not wishing to go against the guys and gals at wiki. But, could there haue been a high pressure system and one of the actions of the planes speed was or is to cause a localised low pressure?
Quote from: another_someone on 09/10/2007 04:29:41As I rather suspected, it is more due to low pressure than to high pressure, but otherwise you are about correct. no way! Ok, not wishing to go against the guys and gals at wiki. But, could there haue been a high pressure system and one of the actions of the planes speed was or is to cause a localised low pressure?
As I rather suspected, it is more due to low pressure than to high pressure, but otherwise you are about correct.