Figure
B.9 shows a 2D
crosssection of a snapshot (in time)
of the
sinusoidal plane wave
for
and
, with
and
in the range
.
Figure:
Grayscale density plot of the
crosssection of a sinusoidal plane wave
, at with vector wavenumber
.

Figure
B.10 depicts a more mathematical schematic of a
sinusoidal plane wave traveling toward the upperright of the figure.
The dotted lines indicate the
crests (peak amplitude location)
along the wave.
Figure:
Wave crests of the sinusoidal traveling
plane wave
, for some
fixed time and
in the plane.

The direction of travel and
spatial frequency are indicated by the
vector wavenumber
, as discussed in in the following section.
Next Section: Vector WavenumberPrevious Section: Air Absorption