Chapter 1

WIND DIRECTION
1-99. Assess wind direction as a magnetic direction from which the wind is blowing.

WIND SPEED
1-100. Assess wind speed in knots.

If an anemometer is available, assess speed to the nearest knot.

If no anemometer is available, estimate the speed in knots. Judge the wind speed by the way
objects, such as trees, bushes, tents, and so forth, are blowing.

VISIBILITY IN METERS
1-101. Observe the farthest visible major terrain or man-made feature and determine the distance using
any available map.

PRESENT WEATHER
1-102. Include any precipitation or obscuring weather. The following are examples of present weather:

Rain―continuous and steady liquid precipitation that will last at least one hour.

Rain showers―short-term and potentially heavy downpours that rarely last more than one hour.

Snow―continuous and steady frozen precipitation that will last at least one hour.

Snow showers―short-term and potentially heavy frozen downpours that rarely last more than
one hour.

Fog, haze―obstructs visibility of ground objects.

Thunderstorms―a potentially dangerous storm. Thunderstorms will produce lightning, heavy
downpours, colder temperatures, tornadoes (not too frequently), hail, and strong gusty winds at
the surface and aloft. Winds commonly exceed 35 knots.

TOTAL CLOUD COVER
1-103. Assess total cloud cover in eighths. Divide the sky into eight different sections measuring from
horizon to horizon. Count the sections with cloud cover, which gives the total cloud cover in eighths. (For
example, if half of the sections are covered with clouds, total cloud cover is 4/8.)

CEILING HEIGHT
1-104. Estimate where the cloud base intersects elevated terrain. Note if bases are above all terrain. If
clouds are not touching terrain, then estimate to the best of your ability.

TEMPERATURE
1-105. Assess temperature with or without a thermometer. With a thermometer, assess temperature in
degrees Celsius (use Fahrenheit only if Celsius conversion is not available). To convert Fahrenheit to
Celsius: C = F minus 32 times .55. To convert Celsius to Fahrenheit: F = 1.8 times C plus 32.

Example:

41 degrees F – 32 x .55 = 5 degrees C
5 degrees C x 1.8 + 32 = 41 degrees F

1-106. Without a thermometer, estimate temperature as above or below freezing (0 degrees C), as well as
an estimated temperature.

PRESSURE TREND
1-107. With a barometer or altimeter, assess the pressure trend.

1-22

TC 3-97.61

26 July 2012