---
title: "What causes a rainbow?"  
description: "What causes a rainbow?"  
author: "Mukul Goenka"  
published: 2023-10-18  
updated: 2023-10-20  
canonical: https://answers.mindstick.com/qa/103886/what-causes-a-rainbow  
category: "science"  
tags: ["science"]  
reading_time: 2 minutes  

---

# What causes a rainbow?



## Answers

### Answer by Saumya Mishra

**Rainbows are formed when light from the** [**sun**](https://answers.mindstick.com/qa/32618/delhi-is-situated-in-bank-of-which-river) **is scattered by [water](https://www.mindstick.com/articles/323154/fluoride-in-your-water-filtration-guide-2020) droplets (e.g. raindrops or fog) through a process called refraction. Refraction occurs when the light from the sun changes direction when passing through a medium denser than air, such as a raindrop. Once the refracted light enters the raindrop, it is reflected off the back and then refracted again as it exits and travels to our eyes.**

[Sunlight](https://www.mindstick.com/news/2153/research-to-cool-earth-by-reflecting-back-sunlight-is-being-advanced-by-the-white-house) is made of many different wavelengths, or [colours](https://yourviews.mindstick.com/view/tags/colour), that [travel](https://www.mindstick.com/articles/44103/5-things-you-must-know-before-visiting-morocco-travel) at different speeds when passing through a medium. This [causes](https://www.mindstick.com/blog/300781/sore-throat-symptoms-and-causes) the white light to [split](https://www.mindstick.com/forum/2357/how-to-split-a-string-in-java) into different colours. Longer wavelengths appear as red and shorter wavelengths appear as blue or violet. We see the colour [spectrum](https://www.mindstick.com/news/1832/government-had-been-successful-in-completing-the-5g-spectrum-harmonisation-process) of the rainbow as the light passes through the [raindrop](https://www.mindstick.com/account/637483/raindrops-infotech) at different angles of approximately two degrees, from red to violet. This is not a true spectrum as the colours mix and blur throughout the spectacle. The angle of scatter from raindrops is different for everyone which means that every rainbow is unique to the [observer](https://www.mindstick.com/interview/2193/how-are-observer-and-observable-used-in-java).

However, for the observer to see a rainbow, they must be in a specific position relative to the sun and water droplets -

- The observer must be positioned, so the sun is behind them.
- The lower the sun in the sky, the more of an arc of a rainbow the observer will see – it must be less than 42° in the sky.
- Water droplets such as rain or fog must be in front of the observer.


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Original Source: https://answers.mindstick.com/qa/103886/what-causes-a-rainbow

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