Why is water blue?
Pure water is very paleblue.[1]
Although water appears clear in small amounts (like a glass of water), the blue color becomes more visible or easier to see as we look through more or deeper water. So deep lakes and seas
Crater Lake in Oregon is a national park. The water in the lake is an intense blue color because of the lake is very deep, 1932 feet deep. The lake was formed by the collapse of a volcano, Mt.Mazama
are more blue than shallower rivers.
Color comes from light hitting things. Most light looks white, but it is really made of a mixture of lots of colored light.
We know this from seeing light hit water -- aRainbowshows us all the colors of light.
When sun hits the rain drops, the rain drops act like a glass prism, separating the white light of sunshine into all the different colors of light
-- making a rainbow.
The blueof water and ice
Water is made by tiny pieces of matter (atoms) sticking together,making a molecule. A water molecule is made with two hydrogen atoms and one oxygen atom or H 2O.
water molecule
The blue of water and ice comes from what happens when light hits a water molecule. Vivid blue icebergs
In a water molecule, the light causes atomic vibrationswhere the centers of the hydrogen and oxygen atoms bounce back and forth. This makes the whole molecule bend and stretch back and forth. These vibrationsof the water molecule are fueled byenergy of the orange and red parts of visible light, so that only blueand violet light passes through the water molecule. This makes water blue!
Three other things can change the color we see when we look at water:
Things in water absorb light
Things in the water can absorb light, which is what makes tea and coffeebrown or black. Green algae in rivers and streams often lend a blue-green color. The Red Sea has occasional blooms of redalgae, which turn reddish brown when they die.
Things in water scatter light
Things in the water help water look blue by scattering bluelight. Some mountain lakes and streams have extremely small pieces of rock that blue and green light bounce off -- turning the waterblue-greenorturquoise.
The color of the sky is reflected in water
The sky is blue because blue light is scattered more easily than the other colors of light. The surface of seas and lakes often reflect blue skylight, making the water appear more blue. But you may know that when the sky is cloudy, instead of sunny blue, the color of the sea may be less bright – a darker, grayer blue.
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[1]If you thought water was clear, don’t worry! Sometimes even experts make mistakes.An expert described water to kids this way: “Pure water is colorless, odorless, and tasteless.” He was right about odor and taste, but wrong about color. The physicists or scientists who study light and color describe water this way: “Water is an odorless, tasteless, transparent liquid that is colorless in small amounts but exhibits a bluish tinge in large quantities.”