Physics of Rainbows and Halos
✅ 1. What is a Rainbow?
A rainbow is a curved band of colors that appears when sunlight passes through raindrops.
The sunlight bends, reflects inside the drop, and then bends again as it leaves.
This process separates white light into colors — red, orange, yellow, green, blue, indigo, and violet.✅ 2. How Does Refraction Work?
Refraction happens when light enters a different medium (air → water), causing it to slow down and change direction.
Different colors bend at different angles because each color has a slightly different wavelength.
This is why red appears on the outer edge and violet on the inner edge of the rainbow.✅ 3. What Role Does Reflection Play?
Inside the raindrop, some of the light reflects off the back surface of the drop.
This reflection sends the light back through the drop toward the observer.
Without this reflection, the rainbow wouldn’t form.✅ 4. Why Is the Rainbow Curved?
Raindrops scatter light in specific directions depending on the observer’s position.
The angle between the incoming sunlight and the scattered light is about 42° for red and about 40° for violet.
This scattering creates a circular arc. From an airplane or higher ground, a full circle rainbow can be seen!✅ 5. What is a Halo?
A halo is a ring of light around the Sun or Moon.
It forms when light passes through ice crystals high in the sky.
These crystals act like tiny prisms and bend light at specific angles, usually 22° or 46°.✅ 6. How Is It Different from a Rainbow?
Feature Rainbow Halo Made of Water droplets Ice crystals Light bending Refraction + reflection Only refraction Angle ~42° 22° or 46° Appearance Bright, colorful arc Pale ring, sometimes with colors ✅ 7. Real-life Examples
Rainbows appear after rain when sunlight shines through remaining droplets.
Halos often form in cold weather when cirrus clouds (made of ice crystals) are present.
Both are natural reminders of how light interacts with the environment.✅ 8. Mini DIY Experiment – How to Make a Rainbow at Home
Materials:
A glass of water
A small mirror
A flashlight or sunlight
A white sheet of paperSteps:
Fill the glass halfway with water.
Place the mirror at an angle inside the glass.
Shine the flashlight onto the mirror through the water or let sunlight pass through.
Hold the white paper next to the glass and move it around until you see a rainbow appear!Why it works:
Water bends and reflects the light, separating it into different colors — the same process that creates rainbows in the sky.
✅ Three-line Summary
Rainbows form when sunlight bends and reflects inside water droplets, splitting into different colors seen in a curved band. Halos form when light bends through ice crystals, creating rings around the Sun or Moon. Both show how light’s interaction with water and ice creates stunning sky patterns.