Satellite pictures tell an interesting story, usually centered around what weather is headed in your direction.
Sometimes, though, they can reveal amazing things.
The path that cargo ships take along the ocean surface can sometimes be seen in satellite pictures. These pathways that show on satellite are called "ship tracks."
To understand ship tracks, we must first discuss how clouds form.
Clouds need more than just water vapor to begin formation. They also need something for water vapor to adhere to. A cloud droplet cannot form without a Cloud Condensation Nuclei (CCN.)
CCNs are sometimes dust particles. In the case of ship tracks, though, the sulfur dioxide in the ships exhaust results in floating sulfate ions. These ions have a magnetic effect when near water vapor, of which there is much above the ocean.
So, the sulfur, acting as a CCN, pulls the water vapor toward itself. This results in a cloud particle. Multiply that by the millions and millions of particles coming out of the ship's exhaust and violà! You get a man-made cloud.
Interestingly, since there are many more ships traversing the oceans in the northern hemisphere than in the southern hemisphere, global warming may be held down a bit in the northern hemisphere. And, scientists have notices a quicker pace to the warming in the southern hemisphere than in the northern hemisphere.