Ice - Water - Halo - Caustics

A delicate 20° tall sun pillar and glitter path at Surf City, New Jersey. Seen by Bill Purdy

Both are thousands or millions of sun glints, the pillar from ice, the glitter in a less than obvious manner from water.  

©Bill Purdy, shown with permission.

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Sunlight glints from the lower faces of crystals and - where imperfections permit - from internal reflections by their upper faces.

The eye intercepts dancing bright caustics and sees them as bright flashes from the waves. Collectively they form a glitter path. The glitter path height and width depends on the maximum water slope within the waves.

Large and therefore wobbly plate-shaped ice crystals glint their sunlight to give the illusion of an upwards pillar. The crystals might be imperfect and even dendritic rather than the perfect hexagons at left.

Sea glints are as from a gigantic fairground distorting mirror that shifts its shape with each passing moment.

Near parallel sun rays are deviated by reflection from the waves. Depending on the wave shape and intensity the rays may then cross and cluster to form sheets of bright light - caustics. This reflection action is similar to that when light enters the water - see here. The dancing bright and ever sharp curves on boat hulls are where they intersect the caustic sheets.

Caustics sweep across the eye. When they do, it sees an intense flash on the wave surface. High speed photography shows more. Pairs of dimmer glints meander across the wave surface; briefly find each other to unite to a caustic flash before separating once more. These are the individual ray pairs that form the caustics.