When we say that something is random, it simply implies that the occurrence under observation does not have any cause or at least that cause cannot be determined beforehand in layman's language. For a scientific mind, every occurrence has to have a cause and must follow some algorithm in order to happen (please correct me here if I am wrong). I wonder could any occurrence in nature be random in the first place? Could any observation may occur without any cause?
In the case of Atmospheric Noise, we do not know what causes it precisely or simply what frequency of atmospheric noise occurs due to what cause or reason is unknown(please update me here if I am wrong). And even then if the cause is "unknown", what really makes statisticians to claim that frequencies of atmospheric noise are purely random?
Here is the official link of the website that uses the service of atmospheric noise for generating random numbers: Random.org
Please explain and justify. Thank you