This handbook focuses on transmission in and through the lower atmosphere,
the region of the atmosphere where weather phenomena occur. The
properties of the lower atmosphere are highly variable and change hourly,
daily, monthly, and yearly. Their effects on radio wave propagation produce
random variations in the amplitude, phase, frequency, polarization, coherence
bandwidth, delay spread, and propagation direction of the electromagnetic
waves. Knowledge of the statistics of one or more of these effects may
be necessary for system design.

• Teacher: lee 李旺秋