How is a rainbow formed?

The formation of a rainbow is a natural optical phenomenon.

Simply put, the rainbow we see after each storm is caused by sunlight shining on small, nearly round water droplets in the air, causing the light to be dispersed and reflected. When sunlight shines on water droplets, it will shine at different angles, the small water droplets will also be reflected at different angles, in which the reflection at an angle of 40 - 42 degrees is the strongest, creating the rainbow that 'we see'.

About the principle of rainbow: when sunlight shines on water droplets in the air, the light is refracted and reflected, forming a colorful arc-shaped spectrum in the sky.

In summer, the sky clears after the rain and the sun shines brightly. The moment the sky appears, the rainbow looks like a colorful ribbon spread across the sun with red, orange, yellow, green, blue, indigo, and violet.

Why do rainbows have many colors appearing in the sky?

The colors of the rainbow originate mainly from the dispersion effect of the prism on white light, which is resolved into 7 distinguishable colors and due to internal reflection, this color range is reversed.

Generally, the larger the raindrop, the brighter the rainbow. Raindrops of different sizes will produce different rainbow colors, even white rainbows.

So why is the rainbow curved?

The rainbow is curved because light of different colors is refracted by water droplets at different rates.

Because the Earth's surface is curved and covered by a thick atmosphere, the water content in the air after a rain is higher than normal and refraction occurs when sunlight hits small water droplets in the air.

Along with that, because the atmosphere on the Earth's surface is arc-shaped, sunlight is refracted on the surface to form the arc-shaped rainbow that we see.

Rainbow is a wonderful natural phenomenon (Photo: pixabay)

Little known facts about rainbows

Rainbows rarely appear at noon.

Rainbows are usually seen in the morning or evening, due to the dispersion of sunlight when refracted and reflected through raindrops at a temperature of about 42 degrees Celsius. The temperature is usually higher than the appropriate level at noon, so rainbows rarely form.

Rainbows can appear at night

Rainbows that appear at night are called moonbows. This phenomenon occurs because rainbows are created by light reflected off the surface of the moon, not from direct sunlight.

It is impossible to see all the colors of the rainbow.

In addition to the seven basic colors of the rainbow that we often see, it is also made up of more than a million consecutively dispersed colors, including colors that are invisible to the naked eye.

Multiple rainbows can form at the same time.

The observer can see more than one rainbow at a time as light refracts inside the droplet and breaks into its component colors. A double rainbow appears when this happens inside the droplet twice, a triple when it happens three times, and even a quadruple if it happens four times.

Minh Anh (synthesis)

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