The number of visible rainbows after rain depends primarily on the number of internal reflections sunlight undergoes within raindrops. This phenomenon is governed by the laws of optics, with each reflection producing a distinct rainbow.

• Primary Rainbow:
  • Formed by a single internal reflection within raindrops.
  • Appears at an angle of 42° from the antisolar point.
  • Colors: Red on the outside, violet on the inside.
  • Most commonly observed.
• Secondary Rainbow:
  • Formed by two internal reflections within raindrops.
  • Appears at an angle of 50-53° from the antisolar point.
  • Colors: Red on the inside, violet on the outside (reversed).
  • Fainter due to light loss during the second reflection.
• Higher-Order Rainbows:
  • Formed by three or more internal reflections within raindrops (tertiary, quaternary, etc.).
  • Progressively fainter and harder to observe due to reduced intensity and sun glare.
• Factors Influencing Visibility:
  • Sun Angle: Lower angles (around 42° for double rainbows) increase the chance of multiple reflections.
  • Raindrop Size: Larger raindrops result in brighter rainbows due to less light scattering.
  • Viewing Angle: Optimal angles are crucial for observing higher-order rainbows.
  • Environmental Conditions: Ideal conditions include large, uniform raindrops and bright sunlight at a low angle.
  • Intensity of Sunlight: Brighter sunlight enhances the visibility of rainbows.
  • Observer’s Position: Position relative to the sun and raindrops affects the visibility and number of rainbows.