Shaving Cream Prank or Ship Tracks?   I could have sworn I saw
this same foamy pattern the other day while cleaning my oven,
but no, this is NASA’s latest image of ship tracks over the
northeast Pacific Ocean near the coast of Oregon and Washington.
The microscopic particles, or aerosols, in ship engine exhaust
make good seeds for water condensation under the right
atmospheric conditions, creating the clouds in their wake. Years
ago it was debatable whether these anthropogenic clouds were
helping to cool the Earth or warm it. Last I heard the verdict
was that the clouds trap more heat in the lower atmosphere,
thereby warming things up.  But the NASA Earth Observatory folks
report a new twist to this:  The aerosol particles may be
natural—such as desert dust or sea salt—or artificial, including
the particles emitted by ships. The particles in ship exhaust
are more abundant than natural airborne particles such as sea
salt, so they generate more and smaller cloud droplets. Because
of this, ship tracks tend to be