The Mysteries of Sea Mist

Atmospheric discoveries at the air-ocean interface


If you’ve ever walked along the shore and inhaled deeply, you’ve probably sensed it. Sea spray contains far more than water. As the briny, earthy aroma indicates, the tiny aerosol droplets also carry salts as well as organic compounds. And, as it turns out, these additional molecules have a profound impact on the earth’s climate.

As water evaporates at the surface of the sea, it rises to form clouds. Wave action creates aerosols—microscopic airborne particles trapped in water droplets. These aerosols influence the formation and physical properties of clouds, such as their ability to absorb sunlight or trap heat.

Climatologists explain that, depending on their chemical makeup, different aerosols scatter or absorb sunlight to varying degrees.  In fact, according to NASA, an aerosol’s effect on light depends primarily on the composition and color of the particles. In general, “bright-colored or translucent particles tend to reflect radiation in all directions and back towards space. Darker aerosols can absorb significant amounts of light.”

Salt particles, sulfates, and nitrates therefore tend to be more reflective and have a cooling effect on the atmosphere, according to a recent study, whereas black carbon absorbs radiation, warming the atmosphere. Organic carbon, sometimes called brown carbon or organic matter, can also have a warming influence on the atmosphere, depending on the brightness of the underlying ground.

“Sea spray aerosol was thought for a long time to be just salt—sodium chloride—and that’s not true,” Vicki Grassian a distinguished professor in the departments of Chemistry and Biochemistry, Nanoengineering, and the Scripps Institution of Oceanography at UC San Diego told Ensia. “There’s a lot more that comes out of the water—viruses, bacteria, organic compounds, parts of cell walls—little ‘bio bits,’ if you will.” Scientists believe that understanding these aerosols and their chemical compositions is critical to understanding cloud formation and fluctuations in the Earth’s climate.

Cloud formation has been extremely difficult to capture in mathematical formulas in the past. Part of the difficulty can be attributed to the fact that traditional calculations have been completed using principles governing pure water molecules. Aerosol studies such as Grassain’s have demonstrated that, in order to be mathematically precise, cloud formation formulas will need to be adjusted to accommodate different molecular compositions. Scientists are hopeful that understanding these variables will help make future weather models increasingly accurate.

I find it exhilarating to reflect on the fact that such a tiny unit of water—an aerosol—can impact the global environment. What are your thoughts? Do you think that aerosol studies may enrich our understanding of the Earth’s climate? WE_bug_web

  • Sea spray studies are critical in my opinion as far as it relates to human health and sustainability studies as it relates to atmospheric sciences. Growing up on the ocean I always felt invigorated by the sea mist and swimming. Keep up the investigation.

  • Mike Mecke.

    Excellent article Laura! Very interesting and informative. I did not realize all of the weather values and implications, or the varied composition. In touring your fabulous CA redwoods and the upper NW coastal rainforests, I believe I remember reading that the coastal mists and fog were crucial to their existence. That is a wonderful blessing from the sea. We have coastal mists here on the Texas section of the Gulf of Mexico, but once in a while they can be deadly – when we get what is called a Red Tide. A harmful algae bloom that can be toxic to fish, inverts and even plants on shore. I know people who were on the beach area during those events and who stayed out and breathed too much and became sick with allergies or breathing issues. Your Pacific variety is a lot nicer. thanks.

  • Milton F Knight.

    An interesting brief article Laura: We often reference the process of phase change of water as leaving behind the contaminant. Consider the desalination of salt water, the evaporation of waste liquids. To some degree that is true. It appears this article is talking about the material that is left behind at the surface or within a range above the water. We know there is an energy exchange which triggers the phase change. We also know that salt has very strong bond and affinity for the water molecule, so the separation requires very low humidity and higher temperature. What is left behind is a condensate nuclei of salt or of organic matter or other inorganic matter. The water vapor rises because it is lighter than air and in the adiabatic process begins to cool as it rises. The air also has lots of very small dust particles made up of salts, bacteria, sand and outer space material that help seed the water vapor as it begins to condense. Once the condensed water vapor gets heavy enough and the air currents (i.e. down drafts-up drafts), cold fronts that condense the water vapor at a faster rate, the water vapor becomes large enough and heavy enough to generate rain which falls to the earth. I cannot image how to build an algorithm that could simulate this process. Imagine how complicated it would have to be. You would need an algorithm for water temperatures, and their currents, tides and flows as well as how they are heated by the sun. Then you need similar algorithms to look at air currents and the flows around the earth as well as their interaction and movement caused by water currents. Think of the amount of moisture created, sucked out of the air with Katrina and Irma, and deposited back on earth. This of the dust, bacteria, sand, contaminant that is has spread as part of its process. Is it concentrating or diluting? I don’t know.



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