Why do some rainbows look brighter than others?

In one line

The rule

The brightness of a rainbow depends on the amount of sunlight, the size and number of raindrops, and the angle at which you see it.

Let's understand it simply

Imagine you are playing cricket after a rain. Sometimes, you see a bright, colourful rainbow. Other times, the rainbow is faint or hardly visible. This happens because a rainbow is made when sunlight enters raindrops, bends (refracts), bounces inside (reflects), and then comes out, spreading into colours. If there is more sunlight and the raindrops are big and many, more light gets bent and reflected to your eyes, making the rainbow look brighter.

How it works

1. Sunlight shines on raindrops in the air after rain.
2. Light bends (refracts) as it enters each drop.
3. Inside the drop, light bounces (reflects) off the back.
4. Light bends again as it leaves the drop, splitting into colours.
5. If there are many big drops and strong sunlight, more light reaches your eyes, making the rainbow brighter.
6. If the sun is low in the sky (morning or evening), the rainbow can also look brighter.

The story behind it

Rainbows have amazed people for thousands of years. Scientists like Isaac Newton studied how light splits into colours. He showed that white sunlight is made of many colours, which we see in a rainbow. Newton used a glass prism to prove this, helping us understand why rainbows form and why their brightness changes.

Where you see it in real life

• After a heavy monsoon shower with bright sunlight: The rainbow is usually bright because there are many big raindrops and strong sunlight.
• Spraying water with a pipe in your garden: If the sun is shining, you can make a small, bright rainbow.
• Looking out of a bus window during rain: Sometimes, you see a faint rainbow if the sunlight is weak or the raindrops are tiny.
• Near waterfalls like Jog Falls: The mist and sunlight together make bright rainbows.
• Early morning or late afternoon: The sun is low, and the rainbow can look brighter and higher in the sky.

Why it matters

• Understanding rainbows helps us learn about light and how it behaves.
• It is used in science to explain refraction and reflection, which are important in optics (the study of light).
• Knowing about rainbows helps photographers and artists capture them better.
• It connects to later chapters on light, colours, and weather.

Common mistakes

• Thinking rainbows are always the same brightness: They change with sunlight and raindrops.
• Believing you can touch a rainbow: It is just light, not a real object.
• Forgetting that your position matters: Move, and the rainbow may look different or disappear.

Remember it

A rainbow is brightest when the sun is strong and raindrops are big and many—just like a cricket ball shines best in bright sunlight.