CHAPTER 1
SURFACE OBSERVATION ELEMENTS
INTRODUCTION
In this chapter, we give you an overview of Surface
Weather Observations and provide references for
observation procedures. We also discuss some of the
important values that weather observers calculate from
observed data. These values include both physiological
indicators and aircraft performance indicators.
Physiological indicators are values that help estimate
the effects of weather on the human body, and aircraft
performance indicators are values that allow aviators to
assess the effects of weather on aircraft.
CONDUCTING OBSERVATIONS
LEARNING OBJECTIVES: Identify
measurement systems and time standards used
while conducting surface weather
observations. Recognize the general order in
which elements are routinely observed.
Throughout the Navy and Marine Corps,
Aerographer’s Mates, Quartermasters, and Marine
Corps weather observers use similar techniques and
procedures to determine the current weather conditions.
Accurate and timely submission of environmental
observations are basic to the development of
oceanographic and meteorological forecasts and
tactical indices used in support of fleet operations. The
methods used aboard ship differ slightly from those
used at shore stations. In this section, we discuss
procedures used both aboard ship and ashore.
Some weather elements are observed by using
different criteria, depending on the recording format
and reporting code used. As of July 1996, all U.S. Navy
weather activities have adopted the Aviation Routine
Weather Report (METAR) and the Aviation Selected
Special Weather Report (SPECI) codes for weather
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observation procedures. The criteria for these codes are
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covered in detail in chapter 3 of this module.
The criteria for U.S. Navy surface aviation weather
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observations ashore are contained in Surface METAR
Observations User’s Manual, NAVMETOC-
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COMINST 3141.2. There are minor differences in
observation criteria between U.S. shore stations and
activities located outside of the continental United
States (OCONUS). These differences are highlighted
in the manual. United States Navy Manual For Ship’s
Surface Weather Observations, NAVMETOC-
COMINST 3144.1, is used for shipboard weather
observations. Except when necessary, we will not
repeat information covered in those manuals, but will
refer you to the manual.
Before discussing the procedures or methods used
to observe weather elements, let’s review some basics
about observing and measuring the elements.
MEASUREMENT SYSTEMS
In the mid-1970's, the United States began
switching to the metric system for weights and
measures. In the field of military meteorology and
oceanography, it is common to measure an element by
using units from the old system and then converting the
measurement to the metric system. Because of this,
weather observers should be well versed in both
systems and be able to convert units of length, volume,
temperature, pressure, and mass. Appendix II of this
module contains tables and conversion factors to
convert from one system to another. Weather observers
make temperature conversions most frequently.
The three temperature scales used are the
Fahrenheit, Celsius, and Kelvin scales. The United
States and several other countries still use the
Fahrenheit scale, which fixes the freezing point of water
at 32°F and the boiling point at 212°F. Most of the world
uses the Celsius scale, which fixes the freezing point of
water at 0°C and the boiling point at 100°C. In
meteorology and oceanography, both temperature
scales are used, with frequent conversions between the
two. Conversions may be made by using a conversion
table or by using the following formulas:
F = –C + 32
or
C = –(F – 32)
where F is degrees Fahrenheit, and C is degrees Celsius.
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