Have you ever wondered why a glass of water is colorless but the ocean is blue? Let’s dive into the physics of it.
Visible light is perceived as a spectrum of colors and these colors match to a certain wavelength of light. Violet is on the shorter end of the spectrum while red is the longest wavelength on the opposite end of the spectrum (remember ROYGBIV). Water molecules in a drinking glass are not in an amount great enough to absorb light. Therefore, the liquid appears colorless. But think about how vast the ocean is- there are a lot of water molecules that can interact with light!
Here’s how it works… Sunlight hits the surface of the water. As light penetrates through, the ocean absorbs red light, in addition to yellow and orange because they are longer wavelength light. Blue light is the least absorbed by the water, so the ocean looks blue to us! The variations in blue that we see correlate to the depth of the water. The deeper that light penetrates into the ocean, the deeper blue that we perceive. This means that gorgeous turquoise color water we all associate with a tropical paradise is relatively shallow… and waiting for you to dive in!