Why does the wingtip of the wing sweep white smoke when the plane is traveling at high speed?

I think you should go and see how they use that colored smoke in aerobatics, and you'll probably know the answer.

It is common to see jets flying high in clear skies, with one or more long lines of "white smoke" behind the fuselage, which is commonly referred to as "airplane smoke". In fact, this is not the smoke emitted by the jet aircraft, but the exhaust gas emitted by the aircraft is mixed with the surrounding air, and the water vapor condenses into a special cloud system, which is called the aircraft wake in the aviation flight community and aviation meteorology, which is commonly known as "aircraft smoke". So, how did it come to be?

According to the cause, aircraft wake can be divided into exhaust gas trail, aerodynamic trail and convective trail. Exhaust gas trails can be divided into exhaust gas condensation trails and exhaust gas evaporation trails. One of the most common is the exhaust gas condensation trail, which is the aircraft contrail that this article focuses on.

The aircraft consumes a large amount of fuel when flying, and the water vapor and part of the heat generated are discharged out of the aircraft with the exhaust gas, enter the atmosphere, and quickly mix with the surrounding air to form contrails. The process of its formation is different from the dew, frost and clouds in the air that people commonly see on the ground. The exhaust gases emitted by the aircraft at high altitudes are mixed with the ambient air, and the saturation of this mixture depends on the net effect of both heat and water vapour increases.

When the humidification effect prevails and exceeds a given threshold, contrails are formed; When the heat gain effect is dominant, no condensation occurs and no condensation trails appear. Since the heating and humidification effects of the exhaust gas are certain, whether there will be condensation in the mixture will depend on the temperature, humidity and atmospheric pressure of the ambient air itself. In short, high ambient air temperatures are not conducive to the formation of contrails, and aircraft contrails are only possible when the ambient temperature is quite low (usually below minus 40 degrees Celsius).

According to the relevant data, when the aircraft wake appears, the air temperature is mostly minus 41 degrees Celsius - 60 degrees Celsius, accounting for about 86 of the aircraft wake, if the air temperature is higher than minus 40 degrees Celsius or lower than minus 60 degrees Celsius, the phenomenon of aircraft wake generally rarely occurs.

The seasonal variation in the height of the aircraft's wake is not obvious, and in general, it occurs more often in the winter half of the year than in the summer half of the year. The average thickness of the wake layer is 1-2 km, and the lower limit height is the lowest in winter and the highest in summer. In thicker aircraft contrails, the length and concentration of wakes formed at different altitudes are also different.

Usually at the bottom of it is a short and light-concentrated trail, which gradually lengthens and thickens upwards, and when it reaches a certain height, it becomes an intermittent and light-toned trail again.

Why is there a white smoke in the sky when the plane flies by, is it because the plane sprays something?

This is due to the separation of the air flow at the outer edge of the wing, resulting in turbulence, which causes the air pressure to decrease there, which causes the saturated water vapor to condense. Similarly, the propeller also condenses the supersaturated water vapor at high altitude, resulting in a condensation end.

It is easy to see that the wings are covered with a layer of mist when taking off on a rainy day, and this is also true.

However, not all aircraft can create such wake clouds, and wake clouds can only be produced when the air humidity is close to or saturated when the jet is flying in an air layer below -20, and the atmosphere is relatively stable. The principle of wake cloud formation is that when the jet aircraft is quite cold and has a large water vapor content in the high-altitude aircraft, the exhaust gas ejected from the tail of the aircraft becomes an "aerosol catalyst" for artificial cloud formation, so that the low temperature and high humidity condense into cloud bands.

Another process in which wake clouds are generated is when an aircraft is flying in near-saturated air, and the air near the tips of the propellers and wings is adiabatic and cooled by dynamic depressurization, but this is a rare occurrence.

The white fog that appears on the wings of a fighter jet during flight is called a Plante-Graue decondensation cloud, also known as a "sonic boom cloud". Sonic boom clouds are a natural phenomenon that occurs when an aircraft is in flight.

The speed of sound in the air is different at different temperatures and atmospheric pressures. At 1 atmosphere and 15 degrees Celsius, a value of 1224 kilometers is equivalent to 340 meters of seconds. As the flight altitude increases, the atmospheric pressure gradually decreases and the air temperature decreases, resulting in the slower the speed of sound at higher altitudes.

For example, at an altitude of 10,000 meters, the speed of sound is only about 300 meters per second (1,080 kilometers per hour). When the speed of the aircraft reaches the speed of sound, it will compress the surrounding air, and shock waves or local shock waves will appear, causing the water vapor in the air to condense into clouds.

So, to be exact, it is more correct that sonic boom clouds should be called condensation clouds. There are three types of condensation clouds: low subsonic irregular condensation clouds, high subsonic cone condense clouds, and supersonic cone condense clouds. Only supersonic cone-shaped condensation clouds are a phenomenon that occurs when an aircraft breaks through the sound barrier.

If you see a white smoke at both ends of the wings during level flight, it is usually the plane performing, and there are 2 pull-up loads at both ends of the wings, which will emit white smoke.

In addition, if you see smoke on the wings of the fighter jet when it is doing up and down or left and right movements, it is because the two ends of the fighter jet's wings are swept through the air at high speed, the air pressure above the wing is low, and the air pressure below is high, and the moisture in the air changes from gaseous to steam-like state, like pulling a water mist behind.

When the aircraft is maneuvering at high speed, there will be a vacuum area above the wings, and the water molecules will boil at this time, resulting in the formation of a large amount of water mist.

When flying, the air pressure above the wings is low, and the air pressure below is high, and the water vapor liquefies into water mist.

You're probably referring to the sound cone that is produced on the surface when the fighter breaks the sound barrier.

That's not fog.

The airplane tells the high pressure generated by the flight, which presses the water vapor in the air into small droplets, creating a fog.

It has nothing to do with the curved surface of the wing, just like the air pump and tires ** will produce white gas, it is negative pressure, the white fog on the back when turning, and the white line of the wingtip, all because the negative pressure is instantly generated for a few seconds, and the negative pressure is drawn into the wingtip vortex to form a white line. If you are directly exposed to the air, you can see the fluctuations like a heat wave, you can take a high-pressure air hose and spray it into the air Pay attention to the vent You can see his vent There will be heat wave fluctuations, when the speed of the aircraft reaches a certain level, the surrounding air pressure reaches a certain level, and such a heat wave effect (scientific name hit wave) Whether it is the aircraft sound barrier or the instantaneous air pressure of **, there is, this pressure to squeeze the surrounding air to heat the air to produce white fog.

This was deliberate by the aircraft.

There is no such thing as a passenger plane.

Aircraft engine exhaust fumes are artificially emitted during air shows to increase the viewing experience.