A RAINBOW streaked the sky with colour on Wednesday night, arching across the horizon as rainclouds cleared. 

The sweeping semicircle was spotted outside the Oxford Mail's offices in Osney Mead at about 8.30pm, after raindrops finally stopped pelting the ground. 

Bold colours brightened the dreary onset of night, sparking witnesses to share their photos on social media. 

Indie band The Balkan Wanderers sent out this fantastic shot showing the rainbow in all its vivid glory.

Jimbob's Baguettes in Magdalen Street tweeted this incredible photo showing the shock of colour encircling Oxford's famous dreaming spires.

'Andrew Fenton' tweeted a breathtaking snap over Port Meadow, while 'Martin Gorick' caught it over Christ Church. 

What causes a double rainbow? 

Rainbows occur when bright sunlight hits a raindrop. To see one, you must have your back to the sun and be looking up at about 40 degrees above the ground towards an area where there is mist or moisture. The raindrops act as tiny prisms that disperse light and reflect it back at your eye, with the vast array of droplets and the wavelengths of light causing the circular arc of red to blue across the sky.

Double rainbows occur when the light is reflected twice inside the raindrop. This means you can see two different reflections and is also why the colours go in the opposite direction on the second, dimmer rainbow. 

Did you catch a better photo? Tweet it to us @TheOxfordMail