Learn how to summon a rainbow.

While waiting for a rainbow in Yosemite one day some years ago, people passing by saw my tripod and stopped to see what I was photographing. Most grew tired quickly and left after a few seconds of secretly checking me out.

A few stuck around long enough to witness a rainbow come to life and disappear within minutes. Suddenly other photographers started setting up tripods and a flurry of activity developed, shutters snapping and people shoveling around. I had the best spot occupied and I had my tripod set up far in advance. I only had to focus on composition.

The picture I took this day started my career as a photographer: Vernal Fall with Rainbow

We can greatly enhance our chance of capturing inspiring landscape photographs if we are able to predict the light. That day I knew the rainbow would show up and it made the difference.

Where to look for Rainbows

When sunlight reflects from water droplets, we see rainbows. Refraction causes the light to decompose into different wavelengths (colors) just like in a prism.

We do not need to study optics to understand rainbows. The only thing we need to care about is the position of the sun, the water droplets and the photographer.

A rainbow is really a complete circle whose center is usually hidden from us. It occurs at the side opposing the sun on a line connecting the sun, the observer and the water droplets. A rainbow will always occur in the same direction, opposite to the sun, relative to the photographer. Most of the rainbow will be hidden due to the earth and only the top half (or less) will be visible, creating the bow.

Sometimes we can observe a full rainbow. One of the few places where this is possible is on Haleakala in Hawaii. The volcano is the highest point of the island, surrounded by water. During the sunrise and sunset, the sun is momentarily lower on the horizon than the observer. If you are lucky enough to have cloud cover on the opposing side of the sun, your shadow will be projected on the clouds surrounded by a full rainbow. I have not been fortunate enough to have the right conditions for this effect, but I have seen a full rainbow from an airplane you may have too.

Plan for Rainbows

Since we understand rainbows, we can take an active role positioning ourselves for maximum effect. We all love taking photographs of waterfalls, but if we can predict the sun to set behind us while we are photographing the waterfall (looking east/west), we should consider arriving in time for sunset/sunrise for a rainbow effect. If you know where the sun sets, you can position yourself such that your shadow points towards the center of the rainbow.

On the California coast you should expect rainbows only during sunrise, but not during sunset, since you are looking west. On most parts of the Atlantic coast the exact opposite is true, look for rainbows during sunset. You won’t see them during sunrise.

This short article is part of a larger series on learning photography. If you like to follow along, subscribe to my feed.