• Question: How are rainbows formed?

    Asked by grace2112 to Adam, Chris, Eleanor, Jessamyn, Sinead on 18 Nov 2013.
    • Photo: Sinead Cullen

      Sinead Cullen answered on 18 Nov 2013:

      Hi Grace,

      Cool question I love rainbows.

      So how it happens is when when sunlight and rain combine in a very special way. The beams of sunlight separate into the colors we see in the rainbow as they enter a raindrop. Sunlight is made up of different colors that we don’t usually see. When a beam of sunlight comes down to Earth, the light is white. But, if the light beam happens to hit raindrops on the way down at a certain angle, the different colors that make up the beam separate so that we can see them.

      The angle for each color of a rainbow is different, because the colors slow down at different speeds when they enter the raindrop. The light comes out of the raindrop in one color. This depends on the angle it came in and that is why we only see one colour in each band of a rainbow. Light at different angles coming from many raindrops form the rainbow that we see, in stripes of red, orange, yellow, green, blue, indigo and violet.

      Its amazing how rainbows are formed and they are so beautiful.

      Hope this helps Grace 🙂

    • Photo: Adam Murphy

      Adam Murphy answered on 18 Nov 2013:

      Hey Grace

      Sinead’s completely right, I can’t add to her answer, but I would like to add some cool things about rainbows

      It was Isaac Newton who first worked out that light split in that way, to give us all the different colours.

      Sometimes, if you’re up in the air, the angles are just right and you can have a full circle rainbow. They look so cool:

      Sometimes, at sunset, all the other colours scatter away, and you can have just a red rainbow!

      And really cool, we think there’s enough of an atmosphere on Saturn’s Moon Titan to be able to make space rainbows!

    • Photo: Eleanor Holmes

      Eleanor Holmes answered on 18 Nov 2013:

      Hey Grace,

      As Sinead said, rainbows appear in the sky when sunlight is “refracted” through raindrops in the atmosphere. The different wavelengths (colours) of light bend by different amounts and will exit the raindrop at different angles so that we can see the continuous “spectrum”. Have you ever seen the album cover of Pink Floyd’s Dark Side Of The Moon?

      An interesting fact about rainbows is that you can only see them from certain angles. For example, the sun will always be behind you when you see a rainbow. The rain is in front of you when a rainbow appears. The center of the rainbow’s arc is directly opposite the sun. Also you see the rainbow as it is refracted through certain raindrops. The raindrops depending on your position. If your friend is standing across the street and also looking up at the rainbow they will be seeing the light refracted in different raindrops and will therefore be seeing a different rainbow to yours!

      Have you ever seen a double rainbow? This happens when the light is “reflected” inside the raindrop twice. The second rainbow will appear about 50 degrees above the first one and will be fainter because of all the reflecting that has happened. It will also be inverted (The red on the inside and the blue on the outside arc). Sometimes a double rainbow is there but it is so faint that it is hard to see.

Comments