What causes/how is an aeroplane vapour trail produced?

Answer 1

Contrail
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A C-141 Starlifter leaves vapour trails over Antarctica

Boeing 747 in cruise at roughly 35000 feet

Multiple contrails in an area with high airline traffic.

A satellite photo of Nova Scotia showing numerous contrails of jets travelling between the Eastern Seaboard and Europe.
Contrails are condensation trails (sometimes vapour trails): artificial cirrus clouds made by the exhaust of aircraft engines or wingtip vortices which precipitate a stream of tiny ice crystals in moist, frigid upper air.

Contents [hide]
1 Contrail creation
2 Contrails and climate
2.1 Sept. 11th, 2001 Climate Impact "Experiment"
3 See also
4 References
5 External links



[edit]
Contrail creation
Contrails are created in one of two ways:

1. First, the airplane's exhaust increases the amount of moisture in the air, which can push the water content of the air past saturation point. This causes condensation to occur, and the contrail to form.

Aviation fuel such as petrol/gasoline (piston engines) or paraffin/kerosene (jet engines) consists primarily of hydrocarbons. When the fuel is burned, the carbon combines with oxygen to form carbon dioxide; the hydrogen also combines with oxygen to form water, which emerges as steam in the exhaust. For every gallon of fuel burned, approximately one gallon of water is produced, in addition to the water already present as humidity in the air used to burn the fuel. At high altitudes this steam emerges into a cold environment, (as altitude increases, the atmospheric temperature drops) which lowers the temperature of the steam until it condenses into tiny water droplets and/or desublimates into ice. These millions of tiny water droplets and/or ice crystals form the contrails. The temperature drop (and therefore, time and distance) the steam needs to condense accounts for the contrail forming some way behind the aircraft's engines.

2. The wings of an airplane cause a drop in air pressure in the vicinity of the wing (this is partly what allows a plane to fly). This drop in air pressure brings with it a drop in temperature, which can cause water to condense out of the air and form a contrail.

Exhaust contrails tend to be more stable and long-lasting than wing-tip contrails, which are often disrupted by the aircraft's wake and are commonly very short-lived.

[edit]
Contrails and climate
Contrails, by affecting cloud formation, can act as a radiative forcing. Various studies have found that contrails trap outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) at a greater rate than they reflect incoming solar radiation (negative radiative forcing). Therefore, the overall effect of contrails is a warming.[1] However, the effect varies daily and annually, and overall the size of the forcing is not well known: globally (for 1992 air traffic conditions), values range from 3.5 mW/m² to 17 mW/m². Other studies have determined that night flights are most responsible for the warming effect: while accounting for only 25 percent of daily air traffic, they contribute 60 to 80 percent of contrail radiative forcing. Similarly, winter flights account for only 22 percent of annual air traffic, but contribute half of the annual mean radiative forcing.[2]

[edit]
Sept. 11th, 2001 Climate Impact "Experiment"
It had been hypothesized that in regions such as the United States with heavy air traffic, contrails affected the weather, reducing solar heating during the day and radiation of heat during the night by increasing the albedo. The suspension of air travel for three days in the United States after September 11, 2001 provided an opportunity to test this hypothesis. Measurements did in fact show that without contrails the local diurnal temperature range (difference of day and night temperatures) was about 1 degree Celsius higher than immediately before;[3] however, it has also been suggested that this was due to unusually clear weather during the period.[4]

[edit]
See also
Global dimming
Ship tracks
List of environment topics
Chemtrail theory (A conspiracy theory that some contrail-like clouds are the result of high-altitude chemical spraying.)

Answer 2

Combustion products are H2O and CO2. The vapour trail occurs at high altitudes, where temperatures are below -30oC. When hot gases exit the combustion chamber, the water vapour is condensed almost instantly, because of low temperatures. Condensation occurs around impurities in gas stream, such as antidetonators and other "solid" particles. The condensation is so quick that a cloud is formed at some distance behind the plane, when the temperature of gasses drops down to the temperature of environment. Because of turbulations of gas stream, most of the water vapor is concentrated in the middle of the stream. Thus the vapor trail is formed.

Answer 3

as the fuel combusts it produces gases and vapour, and as the temperature is lower at higher altitudes than lower altitudes then the vapour and gases freeze in mid air producing a vapour trail.

These vapour trails according to scientists in the US are having an impact on temperature and climate but global warming far outweighs this.

Answer 4

Fuel combustion in the engines produce water vapor. The water vapor condenses to form the vapor trails. The higher the humidity, the longer the vapor trails will last.

Answer 5

It is a function of air temperature and humidity at the altitude the aircraft is flying. Even a few thousand feet can make a difference. From the ground it is not easy to tell the difference between an aircraft at 27,000 feet and 30,000 feet. Such a small difference can easily be the difference between there being a contrail or not.

Answer 6

The Pilot will throw hot aniseed out of the window.

Answer 7

pollution is the simple answer