Ripple Patterns and Caustic Network in the Dead Sea

June 07, 2016

Sand patterns and caustic network in the Dead Sea

Photographer: Menashe Davidson
Summary Authors: Menashe Davidson; Jim Foster

Shown above is an underwater scene in the Dead Sea showing ripples on the sea floor as observed near Ein Bokek Beach, Israel. To make it easier to enter the water here sharp-edged salt stones were cleared and replaced by sand. The rippled pattern results when currents drag loose sand along the bottom. The direction of the sand ripples is parallel to the shoreline (south-north). Symmetrical ripples such as these are typically observed near shore as waves wash back and forth.

Note also the sun-dappled appearance of the water. This is referred to as a caustic network. On the portion of the beach closest to shore (right side of the photo) the depth is about 16 in (40 cm). Shallow depths, clear water, small wave heights and a relatively bright sea floor are required in order to see this phenomenon – often seen in swimming pools. Basically, the surface of the water acts like a series of lenses where sunlight is alternatively brought in and out of focus. Brighter regions are areas that are roughly in focus while darker regions are out of focus. Since waves propagate across the water, the caustic network does as well. In this case, the direction of the caustic network seems to be influenced by strong winds coming from the southeast. Photo taken on May 10, 2016.

Photo Details: Camera Model: NIKON D7100; Focal Length: 18mm (35mm equivalent: 36mm); Digital Zoom: 1.330x; Aperture: ƒ/18.0; Exposure Time: 0.0010 s (1/1000); ISO equiv: 2500; Software: Windows Photo Editor 10.0.10011.16384.