Ask the Met: How Rainbows Form

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“How do rainbows form?”

Carmen Silva, Orchard Hill Elementary

Rainbows cannot form without clouds and without rain drops. Rain drops do not always need to be reaching the ground and can still form a rainbow in the sky whether the rain is falling to the surface or not.

White light, another term for the sun’s rays, can be broken down into seven different colors. This happens when the rays pass through something known as a “prism.” The seven colors that white light (or the sun) breaks up into are the seven colors that make up a rainbow.

Rain drops act as prisms. So if light is reflected or refracted the right way in the sky, white light can pass through the drop and the seven colors can then be shown through a rainbow.

Meteorologist Alyssa Caroprese