CONTRAILS, MINTRA LEVEL, DRYTRA LEVEL, MAXTRA LEVEL, DISTRAILS

Contrails are formed due to condensation of water vapor exhausted from jet engine to liquid form due to saturation of air. Condensation is the process of conversion of water vapor to Liquid form. Saturation is a situation when air is holding max possible quantity of water vapor at a given temp and pressure and any more water vapor added will condense to Liquid form.
2. SCIENCE BEHIND CONTRAILS: In a jet engine ATF which is a Hydrocarbon is burnt to produce thrust. Chemically Hydrocarbon is reacting with oxygen to produce Co2 and H2O. This Water vapor and Co2 as well as heat is exhausted in the atmosphere. Addition of water vapor to atmosphere increases the relative humidity and addition of heat increases the temperature and reduces the relative humidity. Both act against and opposite to each other. So at lower heights in the atmosphere where temp. is relatively higher, there are negligible chances of air getting saturated due to additional water vapor from engine exhaust but at high altitude where temp is low and air is nearly saturated; this addition of water vapor leads to complete saturation and extra amount of water vapor gets condensed to liquid form and seen as contrails. So Contrails are water vapor exhausted from jet engine getting condensed to liquid form.
3. So first point is that contrails are likely to form at high altitude where ambient temp are low. At higher latitudes on the planet where temp falls at faster rate, they can form at medium levels also.
4. MINTRA LEVEL: Theoretically we can find a value of ambient temp. at which contrails will form and this temperature is called minimum temp (MINTRA) and the height at which this temp prevails in atmosphere is called MINTRA level. So, Contrails are likely to form only above MINTRA level. However it is for sure that Contrails will not form below MINTRA level . Generally, MINTRA level is height at which ambient temp is -45 deg.
5. DRYTRA LEVEL: There is level approx. 2 Km above MINTRA level above which contrails will form irrespective of humidity level in the atmosphere. The water vapor from exhaust itself is sufficient to saturate the air and condensation to take place. So, Contrails are bound to form above Drytra level.
6. MAXTRA LEVEL: As we know that there is a limit to which temp drops in troposphere and that is -56.5 deg at 36090 feet. After that temp is constant till 20 km in tropopause and above tropopause in stratosphere temp starts to increase with increase in height. So there will be a certain height above which temp will be higher than - 45 deg or higher than what is at MINTRA level. So above this height again contrails will surely not form. So to summarize below MINTRA level and above MAXTRA level, contrails will not form. Above MINTRA level, it may form and above DRYTRA level, it will form for sure.
7. In the case of jet aircraft, contrails over Indian sky rarely form below 7 kilometers. The usual height band of formation is 11-14 kilometers. Mintra levels are usually lower in winter than in summer and Mintra levels are lower at higher latitudes. In the extreme north, the mintra level in winter may occasionally be below 9 kilometers.
8. DISTRAILS: When an commercial jet aero plane flies through a cloud below the mintra level, the heat from the exhaust may temporarily reduce the relative humidity of the ambient air to such an extent that the cloud droplets in the wake of the aircraft evaporate completely. If the cloud is thin, a lane is created in the cloud right behind the aero plane and is visible to ground observer. This is known as a dissipation trail (DISTRAIL). So DISTRAILS form below MINTRA level.

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Sir where do you reside

[@captainvijaysharma]

Greater Noida.

[@captainvijaysharma]

Greater Noida.