'Ship Trails' Cloud Structure

But to the brightest beams
Distracted clouds give way...
William Shakespeare, Alls Well That Ends Well, Act V, Scene III
Structure Description
Global Occurrence
Observation Diagrams

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"Convective Cells"
"Ship Trails" Cloud Structure (STS)

"Ship trails" cloud structure consists of stratocumulus (and at its edge of low cumulus) cloud lines.
Clouds of this structure, embedded in a layer of small and low stratus and stratocumulus clouds (which build a convective cells structure), can be observed above a sea areas.

The dimension of such cloud lines reaches as much as 30 km width (sometimes up to 50 km) and up to 1000 km (and more) length.
Cloud top height does not exceed the height of 1-2km, and the albedo is in the range 0.3-0.6.

It is supposed that this structure has an artificial origin, because it is connected with the navigation of vessels.
In the image of visible range it has the higher brightness than the surrounding low clouds, however it can not be recognized in the infrared picture, because the cloud top height are low.
The moving ships give off the fine particles (also called aerosols) and warm exhaust steam.
In a cool and humid atmospheric layer, which is connected with a high-pressure system, these particles become a condensation nucleus of clouds, absorb the humidity and produce the bright clouds. Those consist of the small droplets.
The small droplets reflect more lights (within the visible range) than large droplets, therefore the clouds of "Ship trails" structure have the higher brightness than the surrounding convective cells clouds.
However within the infrared range they can be only badly recognized, because the cloud top height is low and accordingly warm.

The "Ship trails" cloud structure can be observed mostly over North Pacific (close to the west coast of the USA, Aleuts, Kamchatka and northeast coast of Japan) as well as over North Atlantic (west coast of Europe, east coast of Newfoundland), rarely - not far from the Peruvian and Chile coast, coast of Namibia, Tasman Sea.

Global Occurrence Diagram
Global occurrence diagram of 'Ship Trails' Structure


B. Geerts and E. Linacre
Effects of contrails and ship tracks on climate

Japan Meteorological Agency 2002
Analysis and Use of Meteorological Satellite Images, Chapter 3, Cloud patterns

Visible Earth. A catalog of NASA images and animations of our home planet
Ship Tracks in a Stratiform Cloud Layer

Winter Meteorological Processes in the Atmosphere