Northern Lights

The Northern Lights exist in the outmost layer of the atmosphere they are created by electrically charged particles that make the air shine, not unlike a fluroescent light

The northern lights are one of the most spectacular show on earth and can frequently be seen in iceland from september through april on clear and crisp night. the northern lights occur high above the surface of the earth where the atmosphere become extremely thin in an altitude of 100-250km

Aurora results from the emission of photons in the Earth's upper atmosphere, above 80 km (50 miles), from the ionized nitrogen atom regain electrons, and oxygen and nitrogen atoms from the excited state back to the ground state. They are ionized or excited by the collision of solar wind particles channeled down and accelerated along the Earth's magnetic field line; excitation energy lost by the emission of photons of light, or by collisions with atoms or molecules:

Oxygen is unusual in terms of returning to the ground state: it can take three-quarters of a second to emit green light and up to two minutes to emit red. Collision with another atom or molecule will absorb energy and prevent the emission of excitation. The top part is a good atmosphere a higher percentage of oxygen, and so thin that collisions are rare enough to allow time for oxygen to emit red. Collisions become more frequent advanced into the atmosphere, so that the red emission do not have time to occur, and eventually even the emission of green light is prevented.

This is why there are differences in color with altitude, at high altitude oxygen dominate red, then green oxygen and nitrogen blue / red, and finally nitrogen blue / red when the collision preventing oxygen from transmitting anything. Green is the most common of all auroras. Behind it is a pink, green and red light mixture, followed by pure red, yellow (mixture of red and green), and lastly pure blue.

Aurora is associated with the solar wind, ions flow continues to flow out from the Sun. trap the Earth's magnetic field these particles, many of which travel toward the poles where they are accelerated towards the Earth. Collisions between ions and atoms and molecules of the atmosphere causes the release of energy in the form of aurora appears in a large circle around the pole. Aurora is more frequent and strong light during the phase of solar cycle when coronal mass ejections increase the intensity of the solar wind. Viewed from space, this curtain fiery form a thin ring