This beautiful sight is definitely one for the bucket list. The ocean can glow and glitter like the stars in the sky thanks to a natural chemical process known as bioluminescence, which allows living things to produce light in their body. Marine creatures like some fish, squid, tiny crustaceans and algae produce bioluminescence to either confuse predators, attract prey or even lure potential mates.
We humans can witness this natural phenomenon when there is lots of bioluminescence in the water, usually from an algae bloom of plankton. Algae bloom sea sparkle events are caused by calm and warm sea conditions. Sparkling night lights have been photographed across Australia, including in South Australia.
A calm sea is, however, rather the exception. Instead, the sea surface is continuously displaced by waves and thus consists of a myriad of differently inclined planes. The farther these planes are from the horizontal specular point, the more they have to be inclined to reflect a single ray of sun light to the observer, i. Sun glitter is well known to everyone who has ever witnessed a sunset over the ocean and has been studied by scientists for centuries.
In their seminal paper published in , Cox and Munk laid down the foundation for ocean glitter research by explaining the relation between the statistical distribtions of surface slopes and sun glitter. The actual pdf tends to have higher probability for very small and very large slopes than a Gaussian distribution.
Furthermore, the along-wind distribution is skewed, showing a higher probability for downwind slopes than for upwind slopes. This makes sense because the wind pushing the small wind waves causes them to lean downwind. The pdf variance mean-square slope increases approximately linearly with wind speed, indicating that the surface gets steadily rougher as the wind blows harder.
Forty-four years after Cox and Munk flew their BG over the Hawaiian Islands, my colleagues and I set out to examine the ocean wave-slope probability model in more detail. In September , we measured laser-glint patterns from the ship shown in Figure 2 about 20 km off the Oregon Coast in the Pacific Ocean. By counting the number of glints in angular bins as a narrow laser beam was scanned repeatedly over the ocean surface, we derived wave-slope probability density functions that agreed well with the Cox and Munk model under similar conditions.
We also found, however, that the surface roughness depends on the air-sea temperature difference which was nearly zero in the Cox-Munk experiment. Therefore, the wind cannot be determined uniquely from the surface roughness alone. We also used video cameras to record images of the surface illuminated by a wide cone of laser light. Nine successive video frames have been averaged to provide a 0. Large closed loops are formed by glints moving in pairs around waves of finite length and width as the surface undulates.
Similar loops can be seen in the reflection of overhead street lights or the moon from water, or, as shown on the bottom of Figure 4, in the reflection of a camera flash from the water in a swimming pool. When the surface roughness increases, the loops become smaller and change rapidly. In fact, we found that a time series of the number of bright regions in these glint images is a fractal process whose fractal dimension varies with surface roughness.
You do not have to be a remote sensing expert to appreciate glitter patterns. From sidewalk puddles to the ocean, beautiful light shows can be seen by anyone with the attention to notice. Depending on the amount of patience you have for such things, you can either casually notice these patterns or spend hours examining them in detail. Either way, there is much to be learned and much to be appreciated about nature by watching light glittering on water.
Physical Sciences Laboratory. Observations Arctic Climate Shipboard Technology. Home education glittering. Glittering Light on Water Joseph A. Figure 1. Figure 2. How Glitter Patterns are Formed The name "glitter pattern" implies a moving and changing phenomenon.
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