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The stunning video was captured by construction workers on a crane in Russia The phenomenon is often seen by pilots, as its best seen from high viewing point While all rainbows are circular, our view is often blocked from the ground. A construction crew working on a 1,515-foot skyscraper has captured the breathtaking moment a 360-degree rainbow appeared over St. Petersburg. As the footage pans over the continuous circle of the rainbow, it’s almost hard to believe your eyes – but, while it may be a remarkable sight, the phenomenon is not entirely uncommon, as long as you have the right vantage point. Seeing a ‘full circle rainbow’ requires the right sky conditions and the right viewing angle, typically from high above the ground, so these natural wonders are usually only seen by pilots. THE SCIENCE OF CIRCULAR RAINBOWS All rainbows in their complete form are circular, we just can't see them from the ground except for in extremely rare instances where conditions allow it. From the ground, it is only possible to see droplets of water in the sky above us. The angle of the sunlight passing through this water means we only ever see rainbows as an arc from the ground. In reality, a rainbow never truly ends, it is just that the bottom half of the circle is 'blocked' by the horizon. If there are water droplets beneath the viewer, from a high viewpoint it can reveal the bottom half of the circle. The stunning video uploaded to YouTube shows the full breadth of the 360-degree rainbow, appearing to stretch from the sky all the way down to the ground and the water below. It was shot by a worker from the cabin of a massive crane in St Petersburg, where crew are building the 462-meter (1,515-foot) Kakhta Center skyscraper. Being hundreds of feet above the ground, the construction workers were treated to a sight rarely seen by the average person. But, while it may be rare to actually witness the spectacle, the formation itself is not. All rainbows in their complete form are circular, we just can't see them from the ground except in extremely rare instances where conditions allow it. From the ground, it is only possible to see droplets of water in the sky above us. The angle of the sunlight passing through this water means we only ever see rainbows as an arc from the ground. In reality, a rainbow never truly ends, it is just that the bottom half of the circle is 'blocked' by the horizon. Copy link to paste in your message As the footage pans over the continuous circle of the rainbow, it’s almost hard to believe your eyes – but, while it may be a remarkable sight, the phenomenon is not entirely uncommon, as long as you have the right vantage point. Seeing a ‘full circle rainbow’ requires the right sky conditions and the right viewing angle, typically from high above the ground, so these natural wonders are usually only seen by pilots The height of the sun in the sky can determine how much of the rainbow can be seen – the lower the sun in the sky the higher the top of the rainbow. So if viewed from high enough, more of the arc is revealed. If there are water droplets beneath the viewer from a high viewpoint it can reveal the bottom half of the circle. HOW A RAINBOW FORMS Rainbows are created by droplets of water splitting sunlight into its constituent wavelengths, or colours. White sunlight passes through droplets of water and is bent, this is because as light passes from the thin air to the dense water it slows down. This effect is known as refraction, and can be seen whenever a plastic straw appears to bend and enlarge inside a glass of water - the bending light creates an optical illusion. As white light is made up of different wavelengths, or colours, each bends a slightly different amount. Some of the light also reflects off the back of the water droplet and is then bent again as it leaves the drop. This results in a change of direction that can be around 138 degrees. When facing away from the sun, this will result in a person seeing a band of light broken into its constituent colours - the typical seven colours of the rainbow.
