<P> Some chemtrail believers adopt the notions of Wilhelm Reich (1897--1957) who devised a "cloudbuster" device from pipework . Reich claimed this device would influence weather and remove harmful energy from the atmosphere . Some chemtrail believers have built cloudbusters filled with crystals and metal filings, which are pointed at the sky in an attempt to clear it of chemtrails . </P> <P> Chemtrail believers sometimes gather samples and have them tested, rather than rely on reports from government or academic laboratories, but their experiments are usually flawed; for example collecting samples in jars with metal lids contaminates the sample and is not done in scientific testing . </P> <P> Contrails, or condensation trails, are "streaks of condensed water vapor created in the air by an airplane or rocket at high altitudes ." They are the result of normal emissions of water vapor from piston and jet engines at high altitudes in which the water vapor condenses into visible clouds . They are formed when hot humid air from the engines mixes with the colder surrounding air . The rate at which contrails dissipate is entirely dependent on weather conditions and altitude . If the atmosphere is near saturation, the contrail may exist for some time . Conversely, if the atmosphere is dry, the contrail will dissipate quickly . </P> <P> It is well established by atmospheric scientists that contrails can persist for hours, and that it is a perfectly normal characteristic for them to spread out into cirrus sheets . The different - sized ice crystals in contrails descend at different rates, which spreads the contrail vertically . Then the differential in wind speeds between altitudes (wind shear) results in the spreading of the contrail across many miles / kilometers in the sky . This mechanism is similar to the formation of cirrus uncinus clouds . Contrails between 25,000 and 40,000 feet (7,600 and 12,200 m) can often merge into an "almost solid" interlaced sheet . Contrails can have a lateral spread of several kilometers, and given sufficient air traffic, it is possible for contrails to create an entirely overcast sky that increases the ice budget of individual contrails and persists for hours . </P>

What are the white lines that come from planes
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