Why Do Rainbows Appear Only After Rainfall?

Have you ever wondered about the magical arc of colors that appears in the sky after rainfall? That’s a rainbow, a beautiful natural phenomenon that never fails to bring a smile to our faces. But what causes this delightful spectacle? And why do rainbows only appear after rainfall? 

This article will unravel some mysteries behind rainbows. I’ll delve into the science of how they’re formed and share some tips on the best conditions for rainbow spotting. 

Let’s get started.

How Are Rainbows Formed?

Rainbows are formed through a process involving both the refraction and reflection of light, specifically sunlight, within water droplets such as rain or fog. Here’s a step-by-step explanation of how rainbows are formed:

1. Refraction: When sunlight enters a water droplet, it slows down and bends. This is known as refraction.

2. Reflection: The refracted light is then reflected off the inside surface of the droplet.

3. Refraction (again): As this reflected light leaves the droplet, it is refracted again at multiple angles.

4. Dispersion: Sunlight is made up of many different wavelengths, or colors, that travel at different speeds when passing through a medium. This causes the white light to split into different colors. Longer wavelengths appear as red, and shorter wavelengths appear as blue or violet.

5. Observation: The observer must be positioned so the sun is behind them and the rain or fog is in front of 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.

It’s important to note that a rainbow is an optical illusion—it does not actually exist in a specific spot in the sky. The appearance of a rainbow depends on where you’re standing and where the sun (or other source of light) is shining. 

In fact, rainbows are actually full circles, but viewers on the ground can only see the light reflected by raindrops above the horizon. Because each person’s horizon is a little different, no one actually sees a full rainbow from the ground. Each person sees a unique rainbow, as everyone has a different antisolar point and horizon.

Why Do Rainbows Appear Only After Rainfall?

rainbow after rainfall - biotrux

Rainbows usually appear after rainfall because there are many water droplets in the air that act as tiny prisms, splitting the white light into its component colors. The angle between the sun, the water droplet, and the observer determines the color and position of the rainbow. 

The colors of the rainbow are always arranged in the same order: red, orange, yellow, green, blue, indigo and violet. This is because each color has a different wavelength and is bent by a different amount when passing through the water droplet. 

Red has the longest wavelength and is bent the least, while violet has the shortest wavelength and is bent the most. Therefore, red appears at the top of the arc and violet at the bottom.

In short, rainbows appear after rainfall due to the interaction between sunlight and water droplets in the atmosphere.

The Cultural Significance of Rainbows After Rainfall

In many cultures, rainbows are seen as bridges between the earthly and the divine. For instance, in Greek mythology, the rainbow was considered as a path made by Iris, who was the messenger of the gods. 

Similarly, the Norse viewed the rainbow as the Bifrost Bridge, a burning rainbow bridge that reaches between Midgard (the world) and Asgard, the realm of the gods.

In Christianity, the rainbow is a symbol of God’s promise to Noah that He would never again send a flood to destroy all life on Earth. This covenant is seen as a sign of hope and new beginnings.

In Buddhist tradition, the rainbow is a staircase linking the earth to the heavens that the Buddha uses in his descent from Tavatimsa Heaven after preaching the Abhidhamma to his mother.

In Native American cultures, the rainbow is often associated with rain and fertility. It is seen as a sign of abundance and prosperity, especially after long periods of drought.

In African cultures, rainbows have various interpretations. In South Africa, the rainbow is a symbol of unity and reconciliation, and the country is often referred to as the ‘Rainbow Nation’ to represent its multicultural diversity.

These examples illustrate the rich dynamics of meanings and significance that rainbows after rainfall hold in different cultures. It often symbolizes hope, a covenant, or a mystical path connecting the earth and the heavens. 

Their appearance after rainfall is particularly significant, as it often coincides with relief from drought or the promise of a fresh start. Thus, rainbows serve as powerful symbols in cultural narratives worldwide.

Tips for Observing Rainbows

Ideal conditions for spotting rainbows

Rainbows are a beautiful natural phenomenon that can be observed under specific conditions. Here are some tips to increase your chances of spotting one:

  • Weather: Rainbows typically appear when there’s rain and sunshine at the same time. They are caused by the refraction and dispersion of sunlight by raindrops.
  • Sun position: The sun must be behind you and the rain in front of you. The lower the sun is in the sky, the higher the rainbow will be.
  • Rainbow angle: The centre of the rainbow’s arc is always directly opposite the sun. The angle between the incoming sunlight and the line from your eye to the rainbow is always approximately 42 degrees.

2. Best times and locations for rainbow sightings

Knowing when and where to look can also enhance your rainbow-spotting experience:

  • Time of day: The best times to see a rainbow are in the early morning and late afternoon when the sun is lower in the sky.
  • Location: Open areas with a clear view of the sky and the horizon increase your chances of spotting a rainbow. Avoid tall buildings or trees that can block your view.
  • Water bodies: If you’re near a water body like a lake or a large pond, the chances of seeing a rainbow increase. This is because water bodies can create local showers, leading to ideal rainbow conditions.

Remember, patience is key when it comes to observing rainbows. 


Why do rainbows only appear after rainfall?

Rainbows appear after rainfall because the presence of raindrops in the air is crucial for the refraction and dispersion of sunlight. This creates the conditions for a rainbow to manifest.

Can artificial rain create rainbows?

While artificial rain can create water droplets, the conditions for a natural rainbow might not be met. The size and distribution of droplets play a crucial role.

Do all rainbows have the same colors?

Yes. All rainbows have the same seven colors – red, orange, yellow, green, blue, indigo, and violet – arranged in a specific order due to their differing wavelengths.

Are double rainbows rare?

Double rainbows are less common than single rainbows but occur when light undergoes two internal reflections inside raindrops. They display a reversed color order compared to the primary rainbow.


Rainbows are one of nature’s most beautiful phenomena, but they are also the result of a complex interaction between sunlight and water droplets. 

When the sun is low in the sky, and there are raindrops in the air, some of the light rays are refracted and reflected by the water, producing a rainbow. The angle between the sun, the raindrop, and the observer determines the position and shape of the rainbow. 

To see a rainbow, you need to have the sun behind you and the rain in front of you. The best time to observe rainbows is in the early morning or late afternoon when the sun is not too high. Rainbows are not only beautiful but also fascinating. 

They teach us about the nature of light, color, and perception. They remind us of the wonder of our world. 

You can also learn more about where the smell of rain comes from.

Thanks for reading.