Science Smarts: What colour is snow?

By Patty Rooks on January 18, 2025.

This may seem like a silly question, but is snow really white?

I am sure the winter season is not over yet, and there will be plenty more of the white stuff, or is it white?

Hmmm…I do not know about you, but I have been wondering why does snow look white? Water is clear, ice is transparent, rivers, lakes and streams look blue when you pass by them…these all contain the same substance; water. Hmm…what is going on here?

Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

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science assistant

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Three bright flashlights

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blue cellophane

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red cellophane

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green cellophane

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large sheet of white poster paper

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rubber bands or string

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scissors

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ruler

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marker

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dark room

Procedure

1. In a dark room, hang the piece of white poster paper on a clear wall.

2. Using the ruler, measure and then cut a 5 cm x 5 cm square from each of the blue, red and green pieces of coloured cellophane.

3. Take the red piece of cellophane and put it over the bulb end of the flashlight.

4. Secure it with a rubber band or string.

5. Repeat #2 and #3 with the green and blue pieces of cellophane.

6. Have your science helper shut the lights off.

7. Shine the flashlight with the red cellophane on it against the white paper in the room.

8. What do you see?

9. Shine the flashlight with the green cellophane on it just so it is overlapping one edge of the red circle on the wall.

10. What colour do you see now?

11. Due to you only having two hands, this is where your science assistant will come in handy – have the assistant since the flashlight with the blue cellophane just so it overlaps the red and green circles of light. Be patient, sometimes we are not very steady and it may take a couple of attempts.

What is going on?

When the red light was on the wall, you only saw red light. Adding the blue light made it purple. When you add the blue and green light it was a turquoise colour. The red and green made a yellow light. It is fascinating to see that where all three colours of light overlapped, it was actually white! This is because red, green and blue are what are called additive primary colours.

I know that you are asking what does this have to do with snow?? First of all, ice is not really transparent – it bends light (refraction). The ice is acting like a prism, separating all of the colours out, but at the same time, blending them together to create the white colour similar to how we created white in our experiment. Since snow is made up of many ice crystals it actually acts like a prism, bending all of the colours, blending them and creating what we see as white snow!

Patty Rooks, senior scientific consultant PRAXIS, “Connecting Science To The Community.” Contact Praxis at [email protected], http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: 12 826 11th Street SE, Medicine Hat, AB, T1A 1T7 Phone: 403-527-5365, email: [email protected].

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