Twice a day both will be at about the same temperature
and will provide no contrast to IR sensors.
. Wavelength dependence - Each of these loss
phenomena is dependent upon wavelength. Sensors
operating in certain bands have markedly different
characteristics. Remember, the compromise is usually
between better resolution and less susceptibility to
atmospheric phenomena. While resolution increases
with decreasing wavelength, so does weather
sensitivity. Table 10-2 shows how environmental
elements affect wavelengths.
. Lessons learned from the field
Battle experience in desert areas has shown
that the operation of optical instruments
suffers greatly in these environments. Rapid
changes in the index of refraction can
result in the shimmering of images, causing
optical instruments to lose lock-on tracked
Mirages and other refractive phenomena
also add to the confusion.
Frequent airborne haze, dust, sand, and
smoke from both naturally occurring
winds and storms, and horn the battle, can
hamper guidance or surveillance systems
operating in, at, or near optical wavelengths.
The effects are more severe at these
wavelengths than at microwave, UHF, or
WEAX AND AVWX
LEARNING OBJECTIVES: Familiarize
yourself with the procedures for obtaining route
weather forecast (WEAX) or aviation route
weather forecast (AVWX) support. Recognize
the standard format of the two products.
Consider the obstacles a ship underway in the
Pacific in July may have to overcome. The CO feels
uneasy; it is tropical storm season and there isnt a
weather division on board. Knowledge of this subject
area may help the CO accomplish a successful mission.
WEAX or AVWX information is useful to ships
receiving OTSR support as well as for independent
steaming units, since the OTSR service does not include
specifically tailored weather forecasts. WEAX
forecasts are designed for ships without embarked
aviation units, while AVWX is tailored for ships with an
embarked aviation unit.
WEAX/AVWX support services are requested in
the movement report (MOVREP) in accordance with
NWP 10-1-10. Once WEAX/AVWX has been
requested on the initial MOVREP, units should continue
entering the WEAX/AVWX notation to any subsequent
MOVREP to ensure support is continued.
Table 10-2.-How Environmental Elements Affect Wavelengths