Atmospheric Optical Phenomena Research Paper Afterglow

Cause and occurrence of a blue flash
“Air is a refractive medium therefore it bends light. The bending progressively becomes stronger as it light approaches the surface of the earth and as air density increases. At sunset, the sun’s image is elevated to about half a degree above its normal height. Moreover, air, which is dispersive, bends light of different frequencies and amounts” (Vedrenne, 2001).
By viewing the sunset using a telescope, a blue disk is observed to be higher than the red disk. Since the resolution of a naked eye is only 50cm at a distance of 1km, this explains why the blue fringe is not observed at the highest part of the sun.
At sunrise and sunset, the sun’s rays go much longer distance through the atmosphere. The light which reaches the earth already has a big portion of the blue color removed, making the sun appear red. Due to the scarcity of blue light, there is a shift of stimulus towards yellow that makes the yellow color appear more than the blue one.
As it is known that when eyes see a small patch of light, the smaller patch is perceived to shift in color, in the direction of the color complementary to that of the larger patch (Vedrenne, 2001).Therefore, with the large sky expanded in a greenish yellow patch, it appears more biased to be blue green and eventually it is observed as green. A blue flash appears in case the atmosphere is absolutely clear, and so the “scattering does not deplete much of the blue component” (Vedrenne, 2001).
The green flash is more elusive because its index of refraction get higher without any interruption when coming to the earth’s surface. “The gradient of the index of refraction should be higher in order to accelerate dispersion of colors”(Vedrenne, 2001). Due to turbulences in the atmosphere, like anomalies in temperature, abnormal refraction is caused that can usually produce a confused gradient of colors.
Earthquake lights
An earthquake light is an abnormal luminous phenomenon that appears in the sky or close to regions of tectonic stress, seismic activity and or volcanicity. It happens right before or during an earthquake. “Like many light appearances in the sky, earthquake lights are a mystery”. No one can distinctively tell why or how they come about. The lights appear multi colored and are usually brighter during the incident than they before or after.
The lights exist for quite sometime unlike in other phenomena where there is a possibility of mistaken identity. Research accounts that the lights were absent until 1930, where at the time an earthquake occurred in Japan (Freund, 2004) .It has been suggested that the lights appear due to gases released during the earthquakes or due to its forces.