Dewbow

Dewbow on a spiderweb

A dewbow is an optical effect, similar to a rainbow where the dewdrops reflect and disperse sunlight, producing all the colours in the visible spectrum. ^{[1] [2]}

Occurrence

Although rare, dewbows are most common in autumn, when dewdrops form on a dense network of spiderwebs (or rarely on walls, grasses and other vegetation^[3]), where the dew hanging on the webs acts like rain, and diffracts the light. ^[2]

Shape

A dewbow is centred on the antisolar point but as the dew is on a horizontal plane, the bow is not a circular arc, but often elliptical or an open arc shape in a parabola or hyperbola. ^[4] The precise shape of the bow depends on the elevation of the sunlight, and any slope present on the dew covered ground. ^[2]

References

1. ^ Boyle, Kevin. "Dewbow". http://www.atoptics.co.uk/rainbows/dewbow.htm. Retrieved 2009-07-19. 
2. ^ ^{a b c} Dunlop, Storm (2009). Weather. Collins. pp. 151. ISBN 978 0 00 784141 7. 
3. ^ Edens, Harald. "Dew bow". http://www.weatherscapes.com/album.php?cat=optics&subcat=dew_bow. Retrieved 2009-07-19. 
4. ^ Boyle, Kevin. "Dewbow". http://www.atoptics.co.uk/rainbows/dewbow.htm. Retrieved 2009-07-19. 

See also

• Rainbow
• Fogbow
• Moonbow