The people who "go down to the sea in ships" fight a continuous close
battle with the elements that make up the weather. A mariners watch
of weather conditions is of greater importance than it is to most people
ashore. Accurate weather forecasting may not be as vital now as it was
in the days of the sailing ships, but situations still arise when the safety
of a ship and the lives of its crew depend on the evasive action taken to
avoid the full fury of a storm. Even when actual safety is not
considered, possible damage to the ships boats and gear must be
minimized by extra security measures taken well in advance of an
The action taken by ships may be based on the latest weather
information compiled and broadcast by the appropriate Naval
Oceanographic Center. The oceanographic centers base their predictions
largely upon the reports of weather conditions received from ships at
sea. An intelligent weather report from a ship can be made only by a
person capable of accurately observing and (to some extent) interpreting
weather conditions. Aerographers mates are charged with this duty, but
not all ships carry them. On a ship that doesnt have an Aerographers
Mate aboard, the weather observation duties are the responsibility of the
Quartermasters. This chapter, then, is concerned with the weather and
the way it is observed and reported.
The material in this chapter will enable the student to:
Measure, convert, and record barometric pressure.
Determine apparent wind, relative wind, and true wind using
anemometers or visual estimation.
Identify cloud types and match them with their correct heights.
Measure temperature, dew point, and relative humidity.
Convert temperature to Celsius or Fahrenheit.
Observe and report weather conditions using form CNOC 3140/8.
Describe weather conditions associated with fronts.
Recommend course of action to evade storms.