The length of time that a contrail lasts is directly proportional to the amount of humidity that is already in the atmosphere. A drier atmosphere leads to a more short-lived contrail, while an atmosphere that has more humidity will lead to longer-lived contrails. However, if the atmosphere is too dry, no contrails will form. Occasionally a jet plane, especially if ascending or descending, will pass through a much drier or more moist layer of atmosphere which may result in a broken pattern to the contrail, with it appearing in segments rather than in one continuous plume.
Now that jet plane traffic, both civilian and military, can be at anyplace over the globe at anytime, contrails are becoming more and more common. However, contrails have been recorded throughout the history of jet plane travel. Many reports exist from World War II of situations where the accumulations of contrails was so extensive that pilots were unable to keep visual contact with neighbor or enemy planes during combat. Contrails have been recorded from the Sahara Desert to the South Pole indicating that contrails are not constrained to only populated regions of the Earth.
Related categories AERODYNAMICS AND AERONAUTICS
ATMOSPHERIC PHENOMENA AND STRUCTURES
Source: National Weather Service Forecast Office. NOAA
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