Why some colors are not visible under water

It is a well-known fact that water acts as a natural filter, affecting how we perceive colors beneath its surface. When we dive underwater, we may notice that certain colors appear duller or completely disappear. This phenomenon occurs due to the way light behaves and interacts with water. In this article, we will explore the reasons why some colors are not visible underwater.

To understand this concept, let’s start by examining how light and water interact. When light travels through the air, it encounters relatively few obstacles and particles. However, once it enters water, it encounters numerous water molecules and impurities that scatter and absorb light. As a result, the visible spectrum of light is altered.

One of the primary factors that affect color visibility underwater is the absorption of light by water itself. Water absorbs light, especially colors on the longer wavelength end of the spectrum, such as red, orange, and yellow. These colors tend to fade or become indistinguishable as we descend deeper into the water.

The absorption of light in water is due to the presence of molecules like water itself, which absorb electromagnetic radiation in certain wavelengths. The energy from absorbed light is converted into heat, decreasing the intensity of the light reaching our eyes. Thus, colors like red, which have longer wavelengths, are more strongly absorbed, making them less visible underwater.

On the other hand, colors with shorter wavelengths, such as blue and green, can penetrate deeper into the water. These colors are less affected by water absorption, enabling us to perceive them more clearly. It explains why the ocean often appears blue as we swim deeper into it.

Another important factor is the way light scatters underwater. Absorption is not the only process affecting color visibility; scattering also plays a crucial role. When light encounters particles suspended in water, such as algae, plankton, or even tiny bubbles, it scatters in different directions.

Scattering affects shorter wavelength colors more strongly than longer wavelength colors. As a result, blue and green light scatter less compared to red light. This phenomenon contributes to why red appears to disappear underwater, as most of the red light is either absorbed or scattered away, making it less visible to our eyes.

Furthermore, the clarity of the water also impacts color visibility. If water is contaminated with sediments or pollutants, it can reduce transparency, resulting in a cloudier appearance. Cloudiness scatters light particles even further, making colors appear less vibrant and clear.

Interestingly, certain marine flora and fauna have adapted to the underwater light spectrum and have evolved colors that are more visible in aquatic environments. For example, coral reefs can exhibit a wide array of vibrant colors due to specialized pigments and structures that reflect and scatter light in unique ways.

In conclusion, the visibility of colors underwater is affected by various factors, including light absorption and scattering, and the clarity of the water. Colors on the shorter wavelength end, such as blue and green, are less affected and, therefore, more visible underwater. On the other hand, colors like red, orange, and yellow are strongly absorbed or scattered, making them less distinguishable. Understanding these properties helps us appreciate the remarkable adaptations of marine life and the ever-changing visual experience when exploring the fascinating world beneath the surface.