Effect of the Earth’s Atmosphere

The Earth atmosphere is not transparent for all parts of the EM-spectrum. That is fortunate because the high energy part of the spectrum is lethal for bio-organisms and without the filtering effect of the atmosphere, life on Earth would not be possible.


800px Atmospheric electromagnetic opacity.svgCredit: Wikimedia


The graph indicates the transparency of the atmosphere across the spectrum. As can be seen, only the visible spectrum, parts of infrared and parts of the radio wavelengths reach the Earths’ surface and can be observed from ground-based observatories. All other parts of the spectrum can in principle only be observed from space.




atmosphereNASAThe Thin Blue Line; Credit: ISS, NASA  



Thickness of atmosphere
The atmosphere is really very thin. Imagine that you have a globe of the Earth with a diameter of 30 cm.
The effective atmosphere of 480 km is then less than half a millimetre at that scale.
Yet it protects all life on Earth against high-energy radiation from the Sun and outer space.