The different colors in an aurora display are primarily caused by the interaction of charged particles from the solar wind with the Earth's atmosphere, specifically the gases present at varying altitudes. Here’s how the colors are produced:
Oxygen Emissions: – Green Light: The most common color observed in auroras is green, which occurs when charged particles collide with oxygen atoms at altitudes of approximately 100 to 150 kilometers (about 62 to 93 miles).
Red Light: Red auroras are less frequent and occur at higher altitudes (around 200 to 300 kilometers or 124 to 186 miles) where oxygen is less concentrated.
Nitrogen Emissions: – Blue and Purple Light: When charged particles interact with nitrogen molecules at lower altitudes (below 100 kilometers or 62 miles), they can produce blue and purple hues.
Variations in Color: – The presence of different gases and their concentrations at various altitudes influences the colors seen in the aurora.
Altitude Effects:The altitude at which the collisions occur is crucial. Higher altitudes tend to produce red colors due to the lower density of oxygen, while lower altitudes predominantly produce green and blue hues.
The colors of auroras are determined by the type of gas involved in the collisions and the altitude at which these interactions occur, creating the stunning light displays that captivate observers around the world.
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