A natural phenomenon is an observable event which is not man-made. Examples include: sunrise, weather, fog, thunder, tornadoes; biological processes, decomposition, germination; physical processes, wave propagation, erosion; tidal flow, and natural disasters such as electromagnetic pulses, volcanic eruptions, and earthquakes.
The act of:
- Population decrease
- Mineralogic phenomena
- Lithologic phenomena
- Endogenic phenomena
- Exogenic phenomena
- Coupled endogenic-exogenic phenomena
A tornado on May 3, 1999 in central Oklahoma
Atmospheric optical phenomena
Source: "Physiography for High Schools" by Albert L. Arey, Frank L. Bryant, William W. Clendenin, and William T. Morrey. 1911, USA.