1959 US Army Vietnam War Terrain Intelligence ... - Survival Books

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PART TWO
BASIC ELEMENTS OF TERRAIN INFORMATION
CHAPTER 5
WEATHER AND CLIMATE
Section I. WEATHER
46. Definition
Weather comprises the day-to-day changes in atmospheric conditions.
The physical properties and conditions of the atmosphere
that must be measured or observed to describe the state of the weather
are termed the weather elements.
47. Air Temperature
a. Definition. Air temperature is the degree of hotness of freely
circulating air as measured by a thermometer that is shielded from
the sun. The thermometer is calibrated by using the melting point of
ice and the boiling point of water at sea level as standard references.
In most English-speaking countries, the Fahrenheit scale is used, with
the melting point of ice designated as 320 F. above zero and the boiling
point of water as 212 ° F. above zero. Countries using the metric
system employ the centigrade (Celsius) scale, with the freezing point
of water designated as 0 ° C. and the boiling point, 100 ° C. In the
United States. surface air temperatures are indicated in degrees
Fahrenheit and upper air temperatures in degrees Centigrade. Temperatures
may be converted from one of these scales to the other by use
of the following formulas:
C= 5 (F-32o)
5
F= ,C+32o
b. Recording. Temperature data may be recorded in the following
forms:
(1) Mean daily temperature. Average of daily maximum and
minimum temperatures for any specific day.
(2) Mean monthly temperature. Average of daily mean temperatures
for any specific month.
(3) Mlean annual temperature. Average of daily mean temperatures
for any specific year.
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