Sea Salt AOD (550nm)

Sea Salt Aerosol Optical Depth (Sea Salt AOD) measures the light extinction caused by hygroscopic salt particles generated through ocean wave action and transported into the atmospheric boundary layer, providing coastal photographers with insights into the baseline aerosol environment characteristic of marine locations. Sea salt aerosols form through mechanical processes: when wind stress on the ocean surface creates whitecaps, breaking waves, and spray, tiny seawater droplets are ejected into the air. As the water evaporates, crystalline sodium chloride and other salts remain suspended in the atmosphere. These particles span a wide size range from fine mode (0.1-1 micrometer) to coarse mode (1-10 micrometers), with the size distribution heavily dependent on wind speed and sea state. For photographers, sea salt aerosols represent the natural background haze level in coastal environments: unlike episodic smoke or dust events that come and go, sea salt particles are constantly generated by ocean processes and omnipresent near coastlines.

Sea Salt AOD values typically range from 0.02-0.08 in coastal zones under normal conditions, with higher values (0.10-0.20+) occurring during strong onshore winds, storms, or high sea states when wave breaking intensifies. Unlike smoke which creates grey-brown haze or dust which produces warm-toned haze, sea salt aerosols scatter light relatively neutrally with slight cool or white coloration. The photographic impact varies by magnitude: Sea Salt AOD below 0.05 indicates minimal marine haze with good clarity suitable for crisp seascape photography, 0.05-0.10 creates the soft, luminous atmospheric perspective many seascape photographers value for creating depth and mood, 0.10-0.20 produces noticeable haze that softens distant features and mutes colors while maintaining acceptable quality for most work, while values exceeding 0.20 during extreme wind events degrade visibility significantly and create washed-out conditions challenging for photography. An important characteristic of sea salt aerosols is their strong hygroscopicity: these particles readily absorb water vapor from the air, growing substantially in humid conditions and enhancing their light-scattering efficiency. This means the visual impact of a given Sea Salt AOD value depends on relative humidity—during humid conditions, even moderate Sea Salt AOD produces more visible haze than the same AOD in dry air.

PhotoWeather's CAMS-derived sea salt forecasts help coastal photographers understand baseline marine aerosol conditions and anticipate periods of enhanced sea spray production during high wind or storm events. For photographers seeking maximum clarity in coastal landscapes, targeting periods with offshore winds (which transport marine aerosols away from your location) and low sea salt values (<0.05) optimizes conditions, while those embracing soft atmospheric perspective may welcome moderate sea salt (0.05-0.10) for its aesthetic contribution to depth and mood.