A Rainbow Wheel over the BA Planetarium
This photo shows a rare bright rainbow over the BA. Interestingly, a wonderful phenomenon known as the rainbow wheel is also visible. When cloud shadows are directed toward the antisolar point, the point directly opposite to the Sun in the sky, the cloud shadows resemble the spokes of a bicycle wheel. Contrast is, as a result, enhanced.
Photo by Aymen Ibrahem, Senior Astronomy Specialist

On the morning of 12 February 2008, it rained heavily in Alexandria, Egypt. Observing from the BA Plaza, BA Senior Astronomy Specialist, Aymen Ibrahem, captured the image of a rare bright rainbow, showing a fascinating optical phenomenon, known as the rainbow wheel.

A rainbow forms due to the refraction and reflection of sunlight within raindrops. The raindrops may also give rise to a wonderful phenomenon, known as the rainbow wheel, or rainbow spokes. Rainbow spokes are radial cloud shadows, converging towards the center of the rainbow, the point directly opposite to the Sun in the sky.

Due to these spokes, the rainbow may resemble a bicycle wheel. If the clouds are drifting, the rainbow wheel may appear to be revolving. More pictures are presented in the picture gallery below.

Picture Gallery

Fig (1)
Rainbow Wheel over the BA
The photo shows a bright rainbow and the rainbow wheel.
Photo by Aymen Ibrahem, Senior Astronomy Specialist

Fig (2)
The photo shows a bright rainbow and rainbow spokes over the BA
Photo by Aymen Ibrahem, Senior Astronomy Specialist    

Fig (3)
The rainbow grew in size, extending from west to north.

Further Reading

A Spectacular Rainbow Wows Sky Observer
http://www.bibalex.org/eclipse2006/News_Details.aspx?id=215

A Spectacular Rainbow Wows Young Sky Watchers
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Bibliography

Atmospheric Optics (a famous website by Les Cowley)
Light and Optics: Online Meteorology Guide
Hyper Physics (a website presented by the Department of Physics and Astronomy, Georgia State University)

Aymen Mohamed Ibrahem
Senior Astronomy Specialist