Water changes color at different depths due to the absorption and scattering of light. Water molecules selectively absorb certain wavelengths of light, resulting in a perceived change in color depending on the depth.
Sunlight is composed of several colors. When it enters the water, each color behaves differently. Red, for example, is absorbed quickly. This is why at shallow depths, you see little red. In contrast, blue penetrates much further. As a result, the deeper you go, the more blue you see. This also explains why deep waters often have that fascinating deep blue appearance. Other colors like green or yellow behave in an intermediate manner, following similar patterns. This explains why the hues change as you dive deeper!
Water is primarily made up of H2O molecules. It is transparent, but it absorbs certain wavelengths of light. Water molecules mainly absorb long wavelengths such as red and yellow. As a result, colors like blue propagate better. Water can appear blue because blue light is the least absorbed. The presence of mineral salts and other dissolved substances can also influence the absorption of light, further altering the perceived color.
The deeper you dive, the more colors disappear. It starts with red, which is absorbed within the first few meters. In shallow areas, we see objects in color. But as soon as you descend to around 10 meters, red packs its bags. Next, orange and yellow begin to fade, each color having its own critical depth at which it gets swallowed. Beyond 30 meters, almost everything becomes blue or green. This is because blue light travels the farthest underwater. Essentially, at great depths, everything looks a bit more monotonous, just shades of blue and green. Divers know this well; the ocean hides its colors unless you bring your own light.
Particles and organisms present in water play a crucial role in the color we perceive. Phytoplankton, these small floating plants, contain chlorophyll which absorbs red and blue light but reflects green light. These particles often give the water a greenish tint.
There is also zooplankton and other small organisms that can influence the color by filtering light in various ways. Inert particles, such as sand or silt, can make the water more turbid and alter its color by scattering light diffusely. Water rich in organic matter can appear browner or yellowish due to the presence of plant debris. In short, the composition of particles and organisms completely changes the way light interacts with the water, and this greatly influences its perceived color.
The scattering of light occurs when it encounters particles in the water. The light then disperses in all directions. This phenomenon often gives the water a bluish appearance. Blue light scatters more easily than other colors because it has a shorter wavelength.
Refraction occurs when light changes direction as it passes from one medium to another, such as from air to water. The speed of light decreases in water, causing its angle to change. This can make underwater objects appear displaced from their actual position. The intensity and color of the light also change depending on the angle at which one looks at the water, sometimes creating rainbow effects.
Temperature and sunlight play a crucial role. When it's hot, the water can become more transparent. The wind stirs the water, mixing the layers and affecting the color. In rainy regions, rivers bring sediments and nutrients, changing the color. Algae multiply with more light and nutrients, tinting the water green. Pollution flows from cities or factories can also color the water. That's why a paradise beach can look like broccoli soup after a storm or with too many people around!
Did you know that the glacial waters in polar regions often take on a surprising turquoise hue? This is due to the light reflecting off the fine particles of glacial silt suspended in the water.
Did you know that the Red Sea gets its name from the seasonal algae Trichodesmium erythraeum, which take on a reddish hue when they bloom in large quantities? Thus, the color of a body of water can be influenced by the marine life it hosts.
Did you know that the phenomenon of bioluminescence, produced by certain aquatic organisms such as jellyfish, can create spectacular underwater light effects, thereby locally influencing the perception of aquatic colors?
Did you know that at Lake Hillier in Australia, the water has a bright pink color all year round, due to halophilic bacteria and specific algae found in its salty waters? This rare phenomenon fascinates both scientists and tourists.
Sure! Here is the translation: "Yes, marine organisms such as phytoplankton, zooplankton, and certain algae directly influence the color of the water. Through their presence and density, these organisms can give the water green, yellow, brown, or even reddish hues, depending on the pigments they contain."
The depth at which water becomes completely dark depends on the clarity of that water. In clear waters like those of the open ocean, light can penetrate up to about 200 meters. In contrast, in waters rich in organic matter or sediments, this limit can be reached at just a few meters of depth.
Sure! Here’s the translation: "Yes, the weather greatly affects the perceived color of water. For example, on a cloudy day, the water may appear darker or more gray due to the reduced sunlight available. Similarly, after a storm, the sediments and other particles suspended in the water increase, significantly changing its color."
The turquoise color of certain tropical waters is mainly due to the presence of white sand or shallow coral reefs. At shallow depths, sunlight reflects strongly off these very light bottoms and enhances the blue-green wavelengths, giving the water its beautiful characteristic turquoise shade.
Bottled water is often transparent because its volume is too small to absorb enough visible light. In contrast, in large volumes like the oceans, water selectively absorbs certain wavelengths of light, particularly reds and yellows, making bluish tones predominant to our eyes.
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