We've all seen rainbows, but how do they really work?
Operate your own rainbow, then find out!


Primary shows the primary rainbow and its light rays.
Secondary shows the secondary 'bow and its light rays. Notice this bow is seen from different places on the ground; some observers can see a primary, but not a secondary, or vice versa. Lucky people can see both rainbows.
To see both 'bows (but no light rays), uncheck both rainbow boxes in Rain Curtain Mode.

• Rain Curtain mode shows parallel light rays from the sun refracting and reflecting from raindrops at the top and bottom of the rain curtain. Outgoing beams show where the rainbow is visible.
• Multi-drop mode shows three light rays refracting from three raindrops at different altitudes. The color you see depends on the angle of refraction.
• Single-drop mode shows the path inside one drop. Change from primary to secondary to see how the light takes a different path for each rainbow. A secondary rainbow is reflected twice, so it's dimmer.

• Drag the sun-like object (top and right side) to change the angle of the light rays. This changes the time of day.
• Drag the humanoid object to see how distance from the rain affects rainbow location in the sky.
• In multi-drop mode, drag raindrops up and down to see how altitude affects viewing on the ground.