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September 15, 2024 - Contrails over the English Channel
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Numerous thin lines crisscrossed the English Channel in mid-September 2024, each marking the passage of an airplane. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired a true-color image of these contrails on September 13.
A contrail, which is a type of pencil-thin cirrus cloud, forms when hot, humid jet exhaust is expelled into the cold air at high altitudes. At these temperatures—at least -39°C (-38°F)—water vapor can easily freeze onto small particles in the atmosphere and form clouds. When the phenomenon involves particles from the exhaust of aircraft, the resulting long, narrow cloud is categorized as a “condensation trail” (contrail).
Air temperature and humidity of the air affect how long contrails last. When air is dry, contrails last just seconds or minutes. But when the air is humid contrails can be long-lived and spread outward until they become difficult to distinguish from naturally occurring cirrus clouds. Satellites have observed clusters of contrails lasting as long as 14 hours, though most remain visible for four to six hours.
Image Facts
Satellite:
Terra
Date Acquired: 9/13/2024
Resolutions:
1km (121.2 KB), 500m (328.9 KB), 250m (588.1 KB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
Numerous thin lines crisscrossed the English Channel in mid-September 2024, each marking the passage of an airplane. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired a true-color image of these contrails on September 13.
A contrail, which is a type of pencil-thin cirrus cloud, forms when hot, humid jet exhaust is expelled into the cold air at high altitudes. At these temperatures—at least -39°C (-38°F)—water vapor can easily freeze onto small particles in the atmosphere and form clouds. When the phenomenon involves particles from the exhaust of aircraft, the resulting long, narrow cloud is categorized as a “condensation trail” (contrail).
Air temperature and humidity of the air affect how long contrails last. When air is dry, contrails last just seconds or minutes. But when the air is humid contrails can be long-lived and spread outward until they become difficult to distinguish from naturally occurring cirrus clouds. Satellites have observed clusters of contrails lasting as long as 14 hours, though most remain visible for four to six hours.
Image Facts
Satellite:
Terra
Date Acquired: 9/13/2024
Resolutions:
1km (121.2 KB), 500m (328.9 KB), 250m (588.1 KB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
