Ice balloons tinted with food coloring create a lesson in water phenomena for teachers at the Exploratorium. To see Exploratorium physicist Paul Doherty discuss ice balloons and other chilly phenomena, check out Ice Stories: Dispatches from Polar Scientists.
The sun’s light, reflected on water rippled by waves, creates what is known as a “glitter path.” The glitter effect is caused by the sun’s light reflecting off the many wavelet faces, which distorts the image of the light source. A perfectly smooth body of water would act like a mirror and make an image of the sun. The glitter path widens as the sun rises or as the waves get steeper. As the sun sets, the height of the waves shadows the faces of the waves, and the glitter path becomes fainter and fainter.
The next time you see the sun setting, turn your back on it and look in the opposite direction for the anti-twilight arch, a band of colors ranging from reds to purples, created by light from the setting sun. Below the arch, you will see dark blue—the shadow of the earth cast on the atmosphere by the setting sun.
In the picture above, a full moon is rising in the anti-twilight arch. The winter months, when the sun sets earliest, are an excellent time to view an anti-twilight arch. Sadly enough, it also helps if there are pollutants in the air, which contribute to atmospheric scattering, making the colors of the arch more intense.
The piece of Colorado sandstone above is marked with a dendritic, or branching, pattern, formed by a surface mineral deposit (often iron or manganese oxide) that has crystallized. Because the pattern resembles fossilized leaves, this phenomenon is also known as a pseudofossil.
Every apple starts as an apple blossom with five petals. After pollination, seeds develop in the blossom’s ovary in pockets called carpels. The outer wall of the ovary becomes the white, fleshy part of an apple, and the inner wall becomes the apple core, containing seeds for the next generation of apples. Just as the blossom had five petals, the apple has five seed compartments. If you slice an apple in half crosswise, you can see the five sections that hold the apple’s seeds in the shape of a star.
Above: Sandwiched between two pads of glass or plastic, a layer of bubbles looks like a honeycomb. The bubbles form a regular pattern—the common walls of three bubbles meet at 120 degree angles. Each bubble has a common wall with six others, forming a pattern of hexagons