1/f Noise

In terms of power spectra, 1/f noise is intermediate between white noise and Brownian noise.

Here are a sample of 1/f noise, its power spectrum, and plots of power and amplitude against frequency.

Many natural processes exhibit power spectra with 1/f characteristics. Among the examples are

voltage fluctuations in almost all electronic components,

time fluctuations in everything from hour glasses to atomic clocks,

traffic flow on interstates,

the annual flooding levels of the Nile,

voltages across the membranes of your nerves,

and even information patterns stored in DNA.