String of Pearls
July 07, 2009
The photographs above showing raindrops on a leaf were taken following a rain shower, at the edge of a field of lupines, just outside the town of Rangeley, New Hampshire. In the picture on the left, the larger ellipsoidal drop was about one cm in (equatorial) diameter, and the smaller spheroidal one about 3 mm across. Notice that the tinier droplets are nearly spherical; any drop less than about two mm in diameter is spherical by virtue of its surface tension being sufficient to overcome the distorting effects of gravity. Clearly, this is not the case for the largest drop. Also note the reflection of the surrounding lupine leaves in both drops and the correspondingly shaped dark base of the drops where they’re in direct contact with the folded leaf. The asymmetry of the reflection is due to the position of the camera with respect to the axis of symmetry of the drops. Note that the smaller drops may be associated with the heilgenshein, which is a colorless glow in the landscape around the antisolar point caused by the backscatter of sunlight through the drops. I included the picture on the right because I liked the linear array of raindrops! Photo taken in mid June 2009.