A natural phenomenon is a non-artificial event in the physical sense, and therefore not produced by humans, although it may affect humans (e.g. bacteria, aging, natural disasters, death). Common examples of natural phenomena include volcanic eruptions, weather, and decay. Most natural phenomena, such as rain, are relatively harmless so far as humans are concerned.
Various types of natural phenomena include (but are not limited to) meteorological phenomena (like hurricanes, thunderstorms, and tornadoes) and geological phenomena (like volcanic activity and earthquakes).
And some of them are just amazing.