Inside a rainbow, water molecules are the only atoms that are there. The other thing that causes a rainbow is sunlight. This is why rainbows are usually seen during or after rain.

Sunlight is a white light, which is a combination of all different colors that we can see. All the colors in the rainbow have their own amount of energy, and when seen at the same time make white light.

When light travels through rain and hits a raindrop, it bends the light at some angle. For white sunlight, since it is a combination of different colors, the raindrop bends certain colors more than others depending on how much energy they have. This means that red light will be reflected off a raindrop at one angle, and purple light will be reflected at a deeper angle. This causes the rainbow we see in the sky, where all the colors of light are spread out at different angles.

The water molecules just sit in the air and wait for sunlight. When light hits these molecules, the reflected light makes a rainbow in the sky! Hope this answers your question.

Not much - the atoms aren't what causes the rainbow. Rainbows are created by drops of water that reflect light off of the back of the droplet. Because light travels slower in water than it does in air, and because different colors of light travel at different speeds when moving through water, the different colors bend different amounts when passing through a raindrop and being bounced. This smears the white light from the sun into the many colors that make up white light, which is why you see a smear of color.

The atoms of the rainbows you are talking about are actually atoms from the molecule of water, H₂O! After if rains, there’s a lot of water in the sky and when the clouds start to disappear after a storm, light starts to hit those water droplets. The light enters a rain droplet at a specific angle and reflects some of it, which we see as a color. The color that the rain droplet reflects and shows depends on the angle the light enters. That’s why you always see red at the top of the rainbow, and purple at the bottom! One rainbow requires millions of rain droplets to create a rainbow. The rainbow is actually a complete circle, but we only see half of it because it is cut off by the ground.

On the atom level, they are doing the same motions as they are doing in their regular phase. There is no big difference in such small level.

So the only atoms really involved in rainbows are the atoms in water molecules. When the light from the sun hits a water droplet in the air (like after it rains), the light bounces off the back of the water droplet.

When the light leaves the water droplet, it’s now been split into different colors. What the atoms are doing is changing the sunlight in such a way that the sun’s white light is split into multiple colors. To understand rainbows, it’s actually better not to think of it in terms of atoms, but instead in terms of the whole water droplet. When you try to understand what happens with light and atoms, it gets really complicated, really quickly. It’s important to realize that the rainbow isn’t in a single place. You only see a rainbow if you are facing the sun in the right way, and it will always seem far away from you. Keep in mind that the sun’s rays are going to hit the water droplets in the air all at the same time, though you’ll only see a rainbow if you’re standing the right place.

This is a really fun question because you’re using your understanding of atoms and you’ve made a really good guess at how rainbows work. The funny thing is, the atoms themselves aren’t doing much to create the rainbow. The molecule (which is particle made up of one or more atoms) that is responsible for rainbows is water. Do you remember what the formula for water is? It’s H_­2O. Water molecules like to stick to other water molecules and if they are light enough they can float in air. If too many of them stick together, they’ll be too heavy to float and they’ll fall as rain. After a storm, most of the water (that we saw as clouds) has fallen but there is a little bit left in the air. When light from the sun (which contains all colors) passes through these water droplets in the sky, the light separates into its individual colors. When the light splits into its individual colors we see a rainbow! This splitting is called refraction and is really complicated, but it boils down to the idea that every color of light is a little bit different so they interact with the water droplet differently. To summarize, the atoms are making up water molecules that refract each color in white light slightly differently which looks like a rainbow when in the sky.