EM 1110-2-2907
1 October 2003
wavelength used for remote sensing. This region includes a broad range of wavelengths;
on the short wavelength end of the range, microwaves exhibit properties similar to the
thermal IR radiation, whereas the longer wavelengths maintain properties similar to those
used for radio broadcasts.
Table 2-3
Wavelengths of various bands in the microwave
range
Band
Frequency (MHz)
Wavelength (cm)
Ka
40,00026,000
0.81.1
K
26,50018,500
1.11.7
X
12,5008000
2.43.8
C
80004000
3.87.5
L
20001000
15.030.0
P
1000300
30.0100.0
(a) Microwave remote sensing is used in the studies of meteorology, hydrology,
oceans, geology, agriculture, forestry, and ice, and for topographic mapping. Because mi-
crowave emission is influenced by moisture content, it is useful for mapping soil mois-
ture, sea ice, currents, and surface winds. Other applications include snow wetness analy-
sis, profile measurements of atmospheric ozone and water vapor, and detection of oil
slicks.
(b) For more information on spectrum regions, see Appendix B.
i. Energy as it Relates to Wavelength, Frequency, and Temperature. As stated above,
energy can be quantified by its wavelength and frequency. It is also useful to measure the
intensity exhibited by electromagnetic energy. Intensity can be described by Q and is
measured in units of Joules.
(1) Quantifying Energy. The energy released from a radiating body in the form of
a vibrating photon traveling at the speed of light can be quantified by relating the en-
ergy's wavelength with its frequency. The following equation shows the relationship
between wavelength, frequency, and amount of energy in units of Joules:
Q=hν
(2-2)
Because c = λν, Q also equals
Q = h c/λ
where
Q
=
energy of a photon in Joules (J)
Planck's constant (6.6 1034 J s)
h
=
3.00 108 m/s, the speed of light
c
=
λ
=
wavelength (m)
ν
=
frequency (cycles/second, Hz).
2-10
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