Some oceans appear darker than others primarily due to their depth and the way light interacts with water.
The Role of Depth and Light Absorption
The main reason different bodies of water, including oceans, can have different shades of blue and vary in darkness relates directly to how light penetrates and is absorbed by the water.
As light shines through water, the water absorbs different colors of the light spectrum. Red, yellow, and green light are absorbed relatively quickly, even in shallower water. Blue light, however, is absorbed much less efficiently and can penetrate to greater depths.
This is why oceans typically appear blue – the blue light is scattered back to our eyes from the water molecules themselves.
Why Deeper Means Darker
According to the provided information, the deeper the basin, the darker and deeper the colour will be, as the more water there is, the lighter gets absorbed.
- In shallower water, some blue light is scattered back, but some can also reflect off the bottom, making the water appear lighter or even picking up the color of the seabed (like sandy bottoms making water look turquoise).
- In deeper ocean areas, there is a much larger volume of water for light to travel through.
- As light travels deeper, more and more of the colors are absorbed.
- Even the blue light, which travels farthest, is eventually absorbed.
- With less light scattered back from great depths and more light absorbed overall, the water appears a much darker and deeper blue.
Essentially, the sheer amount of water in deeper areas leads to greater absorption of light, resulting in a darker appearance compared to shallower regions or bodies of water.
Other Contributing Factors
While depth and light absorption are primary reasons for variations in darkness and the shade of blue, other factors can also influence the appearance of water, sometimes causing it to appear in colours other than blue. These can include:
- Particles and Sediments: Tiny particles suspended in the water can scatter light differently.
- Algae and Phytoplankton: The presence of these microscopic organisms can tint the water green or even reddish-brown.
- The Sky: The color of the sky reflected on the surface also plays a role.
However, for the distinct difference in darkness often observed between shallow and deep ocean areas, the depth and the corresponding increased absorption of light are the dominant factors, making deeper oceans appear darker than shallower ones.
