Rainbows are normally red, yellow, green and blue – in short, all the colors of a rainbow.
But the rainbow Harlan Thomas photographed near Calgary, Alberta, on June 8th was mainly blood red.
Image above: People in Calgary, Alberta were treated to a spectacular sunset last night which featured an unusual blood rainbow that stretched across the orangered-tinted sky. Picture: Harlan Thomas via Spaceweathergallery
“I was hoping to find some noctilucent clouds and decided to leave a bit early to catch the sunset,” says Thomas. “As I was shooting the setting sun, I looked over my shoulder and my mouth dropped to my knees. There was a rainbow that looked close enough to touch!“
What made the rainbow red?
It was the only color available. All of the other colors of the rainbow had been scattered away by air molecules and dust particles in front of the low-hanging sun.
Indeed, at sunrise and sunset, the sun’s rays are forced to travel through more of the Earth’s atmosphere. Particles in the atmosphere scatters some of the light but light at the red end of the spectrum is less affected – this is why sunsets are red.
Rainbows are formed when rays of light travel through raindrops and are reflected off the back of individual drops. When the light is largely red at sunrise or sunset, it follows that rainbows are also redder.
At certain times there are more particles in the atmosphere and this scatters more light. All colors disappear, except red… And the rainbow appears blood red.