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Only a NASA scientist, or concerned environmentalist recognize that jet exhausts, loaded with water vapor, nitrous oxides, carbon dioxide and other aerosols, are changing atmospheric properties and photo-chemistry and affecting the health and living conditions at our planet's surface.
A 1998 NASA study of jet contrails suggested maximal depolarization ratios were produced by ice crystals with radii as small as several tenths of a µm, explaining why they disappear in less than 20 seconds and so have different radioactive properties than cirrus clouds. In addition to producing vapor trails stretching thousands of miles across the sky, jet exhaust also seeds the atmosphere with cloud-forming aerosols - droplets of sulfuric acid and particles of soot. NASA's tests revealed that, at jet cruising altitudes, acid droplets account for at least 10 percent of the sulfur emissions.
If the atmosphere were warmer than the temperature indicated by the 100% line, a contrail could not form even if the relative humidity of the atmosphere were 100 percent. The combined moisture from the jet exhaust and the atmosphere will never be enough for the mixture to produce a cloud. Temperature profiles to the right of the 100% line will never form a contrail.
Recently, our newly developed VACA ( = Volatile Aerosol Composition Analyzer) instrument was used in the "SULFUR 5" campaign in April 1997, leading to the first direct detection of sulfuric acid in the exhaust plume of a jet aircraft in flight.
Engines can also stimulate cloud growth indirectly, by way of tiny aerosol particles within the exhaust. These aerosols-droplets of sulfuric acid and specks of soot-serve as seeds. They provide surfaces upon which water molecules can condense or freeze to create cloud particles, explains Eric J. Jensen, a participant in SUCCESS and a researcher at NASA's Ames Research Center in Mountain View, Calif.
Results are presented for the mass fractions of SO3 and H2SO4 acquired per soot particle early in the plume, suggesting that sulfur-induced activation is an efficient pathway to increase the ability of exhaust soot emitted at altitude to host heterogeneous chemical reactions and to trigger the formation of cirrus clouds.
Jet engine exhaust contains carbon dioxide, oxides of sulfur and nitrogen, unburned fuel, soot and metal particles, as well as water vapor. The soot provides condensation sites for the water vapor. Any particles present in the air provide additional sites.
Depending on a plane�s altitude, and the temperature and humidity of the atmosphere, contrails may vary in their thickness, extent and duration. The nature and persistence of jet contrails can be used to predict the weather. A thin, short-lived contrail indicates low-humidity air at high altitude, a sign of fair weather, whereas a thick, long-lasting contrail reflects humid air at high altitudes and can be an early indicator of a storm.
1. Contrail generation apparatus for producing a powder contrail having
scattering ability for a given weight material, comprising:
a. an aerodynamic housing;
b. a jet tube means passing through said housing, said tube means having an inlet at a forward end of said housing and an exhaust at a rearward end thereof;
c. a powder storage means in said housing;
d. a deagglomeration means also in said housing;
e. means connecting said powder storage means with said deagglomeration
means for feeding
radiation scattering powder from said powder storage means to said deagglomeration means;
f. the output of said deagglomeration means dispensing directly into said jet tube means for
exhausting deagglomerated powder particles into the atmosphere to form a contrail; and
h. means for controlling the flow of said powder from said storage means to said deagglomeration means.
Ram-jet-like device called an afterburner, attached to the exhaust of a jet-engined ..... Silver iodide smoke particles, created by fire in special burners, ...
The first flight by a commercial airline to be powered partly by biofuel has taken place.
A Virgin Atlantic jumbo jet has flown between London's Heathrow and Amsterdam using fuel derived from a mixture of Brazilian babassu nuts and coconuts.