Ship tracks

In contrast, ships release their exhaust into the relatively clean and still marine air, where the scientists have an easier time of measuring the effects of fossil fuel emissions on cloud formation.

The lower atmosphere is especially calm over the eastern Pacific in the summertime due to a layer of hot air that settles in 500 to 700 meters above that region of the ocean.

The particles billowing from ships' smokestacks enter the air above the eastern Pacific and create long, thin clouds that remain there for days.

[3] It is theorized that sulfur dioxide released from ships' smokestacks could be forming sulfate aerosol particles in the atmosphere, which cause the clouds to be more reflective, carry more water and possibly stop precipitating.

Yet, in ship tracks, the cloud seeding makes the drops so small that they can no longer easily merge to reach the size needed to escape.

[9] As part of a strategy to reduce ship emissions, the International Maritime Organization implemented a global standard in 2020 requiring a fuel sulfur content reduction of 86%.

[10] A study by NASA found that the frequency of ship tracks was reduced to its lowest level in decades due largely to the 2020 global standards, and to a lesser degree by trade disruptions related to the COVID-19 pandemic.