wunder beta

📘 How a rainbow appears

Follow refraction, internal reflection, dispersion, raindrop geometry, and viewing angle.

lessons

~10 min

to learn

🔬 Science

subject

Adults

level

Start the course →

What you’ll learn

Sun and rain
Refraction
Dispersion
Internal reflection
Viewing angle
Arc and circle
Secondary bow
Dark band
Droplet size
Changing view

Questions this course answers

What must be behind the observer for a primary rainbow?

Sunlight must enter raindrops in front of the observer.

What splits white light into colors?

Water's refractive index varies with wavelength.

How many internal reflections make a primary rainbow?

The primary path includes one reflection inside each drop.

Why is a secondary rainbow outside the primary?

The double-reflection geometry produces the larger angle and reversed colors.

Why can a fogbow look white?

Diffraction and small droplet size smear the colors together.

Grounded in trusted sources

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