Natural phenomenon of light

Physics

1. Natural Phenomenon of Light Made By : Ayush Mandal- 23 Bhawana Mahato- 21 Dhrubo Chattoraj- 05 Of Class- 8/D

2. HALO A  halo   is an  optical phenomenon  produced by ice crystals creating coloured or white arcs and spots in the sky. Many are near the sun or moon but others are elsewhere and even in the opposite part of the sky.

3. Aurora An aurora is a natural light display in the sky, especially in the high latitude regions , caused by the collision of solar wind and magnetospheric charged particles with the high altitude atmosphere . Most Auroras occur in a band known as the auroral zone, which is typically 3 degree to 6 degree wide in latitude and observed at 0 degree to 20 degree from the geomagnetic poles at all local times , but often most vividly around the spring and autumn equinoxes . The charged particles and solar wind are directed into the atmosphere by the Earth’s magnetosphere .A geomagnetic storm expands the auroral zone to lower latitudes.

4. Zodiacal Light Zodiacal light is a faint ,roughly triangular ,diffuse white glow seen in the night sky that appears to extend up from the vicinity of the sun along the elliptic or zodiac .Caused by sunlight scattered by space dust In the zodiacal cloud ,it is so faint that either moonlight or light pollution renders it invisible .The dust forms a thick pancake –shaped cloud in the solar system collectively known as the zodiacal cloud ,which occupies the same plane as the ecliptic. In fact the zodiacal light covers the entire sky being responsible in large part for the total skylight on a moonless night

5. Rainbow A rainbow is an optical and meteorological phenomenon that is caused by reflection and refraction of light in water droplets in Earth’s atmosphere resulting in a spectrum of light appearing in the sky . It takes the form of a multicolored arc .Rainbows caused by sunlight always appear in the section of sky directly opposite to the Sun. All rainbows are full circles , however the average observer sees only approximately the upper half of the arc , the illuminated droplets above the horizon from the observer’s line of sight. In a “primary rainbow” ,the arc shows red on the outer part and violet in the inner side . This rainbow is caused by light refracted when entering a droplet of water ,then reflected inside on the back of the droplet tend refracted again when leaving it.

6. Sun Dog A  sun dog  , is an atmospheric phenomenon  that creates bright spots of light in the sky, often on a luminous ring or  halo  on either side of the  sun. Sundogs may appear as a coloured patch of light to the left or right of the sun, 22° distant and at the same distance above the horizon as the sun, and in ice halos. They can be seen anywhere in the world during any season, but they are not always obvious or bright. Sundogs are best seen and are most conspicuous when the sun is low.

7. Anthelion An  anthelion is a rare  optical phenomenon  appearing on the parhelic circle   opposite to the sun   as a faint white halo   , not unlike a  sundog. How anthelions are formed is disputed. Walter Tape, among others, has argued they are not separate haloes, but simply where various haloes caused by horizontally oriented column-shaped ice crystals coincide on the parhelic circle to create a bright spot. If this theory is correct, anthelia should only appear together with these other haloes.

8. Light Pillar A  light pillar  is a visual phenomenon created by the reflection of light from ice crystals with near horizontal parallel planar surfaces. The light can come from the Sun (usually at or low to the horizon) in which case the phenomenon is called a  sun pillar  or  solar pillar . It can also come from the Moon or from terrestrial sources such as streetlights .

9. Alexander’s Band Alexander's band or  Alexander's dark band is an  optical phenomenon  associated with rainbows which was named after Alexander of Aphrodisias who first described it in 200 AD. It occurs due to the deviation angles of the primary and secondary rainbows. Both bows exist due to an optical effect called the angle of minimum deviation . The  refractive index  of  water  prevents light from being deviated at smaller angles.

10. Afterglow An afterglow is a broad high arch of whitish or rosy light appearing in the sky due to very fine particles of dust suspended in the high regions of the atmosphere. An afterglow may appear above the highest clouds  in the hour of deepening twilight, or reflected from the high snowfields in mountain  regions long after sunset. The particles produce a scattering effect upon the component parts of white light.

11. Earth’s Shadow The  Earth's shadow  or  Earth shadow  (also sometimes known as the  dark segment ) are names for the shadow that the Earth  itself casts on its atmosphere. This shadow is often visible from the surface of the Earth, as a dark band in the sky near the horizon. This atmospheric phenomenon can sometimes be seen twice a day, around the times of sunset and sunrise.

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