We’ve seen the dramatic white creatures that live around underwater vents in the Earth’s surface. But what about the vents themselves? There’s no “fire” inside them, so what is the black “smoke” pouring out of them?
Certain types of hydrothermal vents are called “black smokers.” Obviously, what’s coming out of them isn’t “smoke” in the sense that it isn’t the little pieces of carbon-based ash that we see billowing above a fire. It’s the result of the chemical composition of the earth near the vent, and the temperature of the water outside of it.
Water doesn’t just erupt from the vent, it also seeps into the dirt around it. As it moves through the crust of the earth, the water loses components oxygen and sulfates. As it heats up, it is better able to hold dissolved particles of iron, copper, and sulfur.
The water, heated up to 700 degrees Fahrenheit, spews out of the vent and comes into contact with the incredibly cold water on the ocean floor. The metal precipitates out, and comes into contact with sulfur, and forming tiny black specks of metal sulfide. These are the particles that make underwater smoke look just like atmospheric smoke. We’re seeing the same interplay of hot and cold media, and the same tiny compounds in suspension. It’s the substance of the compounds that makes the difference.