Quartermaster Requirement 15
Quartermaster Requirement 15
Demonstrate your ability to read a barometer, thermometer,
anemometer, psychrometer, and weather vane.
Be familiar with the Beaufort scale of winds and seas.
Read and understand a local weather bulletin.
Know how to obtain current marine and weather reports from the
National Weather Service in your area either by telephone or radio.
Know weather signs for your local area, including cloud types, and
prepare a 48-hour forecast from them.
Compare your forecast with the actual weather that occurred.
"Weather" on page 235.
Weather merit badge pamphlet, No. 33274.
Aug-12 Quartermaster 15 - Weather 2
Wind is the flow of air commonly classified by spatial scale, speed, the
types of forces that cause them, the geographic regions in which they occur,
or their effect.
global winds, such as the wind belts exist between atmospheric
upper-level winds typically include narrow belts of concentrated flow
called jet streams.
synoptic-scale winds that result from pressure differences in surface air
masses in the middle latitudes,
winds that come about as a consequence of geographic features, such
as the sea breezes.
mesoscale winds are those which act on a local scale, such as gust
microscale winds blow on a scale of only tens to hundreds of meters and
are essentially unpredictable, such as dust devils and microbursts.
Aug-12 Quartermaster 15 - Weather 3
Forces which drive wind or affect it are
the pressure gradient force
the Coriolis force
and friction forces
Air tends to flow from a region of high pressure to a region of low
On a rotating planet, flows will be acted upon by the Coriolis force
The two major driving factors of large scale global winds are
the differential heating between the equator and the poles
the rotation of the planet
Aug-12 Quartermaster 15 - Weather 4
Description Sea Condition
0 0 Calm Sea like a mirror
1 1-3 Light Air Ripples but without foam crests
2 4-6 Light Breeze Small wavelets. Crests do not break
3 7 - 10 Gentle Breeze Large wavelets. Perhaps scattered white horses
4 11 - 16 Moderate Breeze Small waves. Fairly frequent white horses.
5 17 - 21 Fresh Breeze Moderate waves, many white horses
6 22 - 27 Strong Breeze Large waves begin to form; white foam crests, probably spray
Sea heaps up and white foam blown in streaks along the direction of the
7 28 - 33 Near Gale
8 34 - 40 Gale Moderately high waves, crests begin to break into spindrift
High waves. Dense foam along the direction of the wind. Crests of waves
9 41 - 47 Strong Gale
begin to roll over. Spray may affect visibility
Very high waves with long overhanging crests. The surface of the sea
10 48 - 55 Storm takes a white appearance. The tumbling of the sea becomes heavy and
shock like. Visibility affected
Exceptionally high waves. The sea is completely covered with long white
11 56 - 63 Violent Storm
patches of foam lying in the direction of the wind. Visibility affected
The air is filled with foam and spray. Sea completely white with driving
12 64+ Hurricane
spray. Visibility very seriously affected.
Aug-12 Quartermaster 15 - Weather 5
A visible aggregate of tiny water droplets or ice crystals
suspended in the atmosphere
Can exist in a variety of shapes and sizes.
Some clouds are accompanied by precipitation; rain,
snow, hail, sleet, even freezing rain.
Generally classified based on characteristics such as
altitude, appearance, or origin.
Aug-12 Quartermaster 15 - Weather 6
Clouds may be thick or thin, have well defined edges or
be very diffuse, appear hair-like, cellular, towering, or in
sheets, and be associated with fair weather or
Most clouds form due to upward vertical motion of air.
Often associated with weather producing phenomena, such
as fronts, troughs, and low pressure systems.
Topography can also help move air upwards and produce
Aug-12 Quartermaster 15 - Weather 7
Water existing as a gas is called water
When referring to the amount of
moisture in the air, we are actually
referring to the amount of water
If the air is described as "moist",
that means the air contains large
amounts of water vapor.
Common sources of moisture for the
United States are:
the warm moist air masses that
flow northward from the Gulf of
Mexico and western Atlantic Ocean
the moist Pacific air masses
brought onshore by the westerlies.
Moisture is a necessary ingredient for
the production of clouds and
Aug-12 Quartermaster 15 - Weather 8
Clouds are classified into a
system that uses Latin words to
describe the appearance of clouds Latin Root Translation
as seen by an observer on the
The four principal types of cumulus heap
clouds are summarized in the
table to the left.
Further classification identifies stratus layer
clouds by height of cloud base.
cloud names containing the
prefix "cirr-" are located at high
levels cirrus curl of hair
cloud names with the prefix
"alto-” are found at middle
Aug-12 Quartermaster 15 - Weather 9
High clouds Fog – cloud in contact with the ground
Have bases above 18,000 feet Multi-level clouds – vertically thick
Primarily composed of ice crystals spanning multiple layers
Middle clouds Heavy precipitation producers
Have bases between 7,000 and Orographic clouds – distinct clouds
18,000 feet that form via interaction between wind
Contain ice crystals or water and mountainous terrain features
droplets Produced by the strong flow of air
May be associated with some light interacting with mountainous
Have bases below 7,000 feet
Most often composed of water
droplets, but can have ice crystals
in colder climates
Can produce heavy precipitation,
thunder and lightning
Aug-12 Quartermaster 15 - Weather 10
High Clouds - Cirrus
High altitude wispy clouds.
Typically found at heights
greater than 20,000 feet.
Usually quite thin and often have a
hair-like or filament type of
Composed of ice crystals that
originate from the freezing of
super-cooled water droplets
Curled up ends are very
Generally occur in fair weather
and point in the direction of air
movement at their elevation.
Aug-12 Quartermaster 15 - Weather 11
High Clouds - Cirrocumulus
High clouds that have a
distinct patchy and/or wavelike
(Above Right) A patchwork
composed of many
individual cloud elements
(Below Right) A wavy
cirrocumulus photo with its
banded linear structure.
These features are common to
all types of cumuloform clouds.
Aug-12 Quartermaster 15 - Weather 12
High Clouds- Cirrostratus
High stratiform clouds that
usually blanket the sky in ill-
Usually optically thin and the
sun and moon can usually
shine some light through.
Usually can't detect distinct
cells or sharp features.
Aug-12 Quartermaster 15 - Weather 13
Middle Clouds - Altocumulus
Are either in a patchy, scattered
distribution or can appear in linear
composed primarily of water
droplets and are located
between 6,500 and 20,000 feet
Usually form by convection in an
unstable layer aloft, which may
result from the gradual lifting of air
in advance of a cold front.
The presence of altocumulus
clouds on a warm and humid
summer morning is commonly
followed by thunderstorms later in
Aug-12 Quartermaster 15 - Weather 14
Middle Clouds - Altostratus
Have a more uniform and diffuse
Often difficult to detect individual
elements or features.
Often confused with high-level
A halo is not observed around
the sun (or moon) when
viewed through altostratus as it
is with cirrostratus
In fact, the sun (or moon) is
only vaguely visible through
altostratus clouds and appears
as if it were shining through
Aug-12 Quartermaster 15 - Weather 15
Low Clouds - Cumulus
Usually puffy and often have
very distinct edges and usually
a noticeable vertical
Often have a popcorn-like
Cells can be isolated or
grouped together in
Given suitable conditions, fair
weather cumulus can develop
into towering cumulonimbus
associated with powerful
Aug-12 Quartermaster 15 - Weather 16
Low Clouds - Stratocumulus
Generally appear as a low, lumpy
layer of clouds that is sometimes
accompanied by weak intensity
Can be widely scattered but are
usually concentrated closer
together in clusters or layers and
have very little vertical
Relatively flat clouds usually lack
the sharp edges and "popcorn"
appearance of most normal
Vary in color from dark gray to
light gray and may appear as
rounded masses, rolls, etc., with
breaks of clear sky in between.
Aug-12 Quartermaster 15 - Weather 17
Low Clouds - Stratus
Usually the lowest of the low
Often appear as an overcast
deck but can be scattered.
The individual cloud elements
have very ill-defined edges
compared to most low
cumuloform clouds (e.g.
cumulus and stratocumulus).
Fog can be considered as a low
stratus cloud in contact with the
When the fog lifts, it usually
becomes true stratus.
Aug-12 Quartermaster 15 - Weather 18
Multi-layer clouds - Cumulonimbus
Can produce lightning, thunder,
heavy rains, hail, strong winds,
Are the tallest of all clouds that
can span all cloud layers and
extend above 60,000 feet.
Lower levels consist mostly of
At higher elevations, where
temperatures are well below 0
degrees Celsius, ice crystals
Usually have large anvil-shaped
tops that form because of the
stronger winds at those higher
levels of the atmosphere.
Aug-12 Quartermaster 15 - Weather 19
Multi-layer clouds - Nimbostratus
Often included in many texts as
Vertical extent often goes well into
the middle cloud region
Often have even taller
cumulonimbus clouds embedded
Are very dark, usually overcast,
and are associated with large
areas of continuous precipitation.
On a gray and rainy day, the sky
most will most likely be filled with
Aug-12 Quartermaster 15 - Weather 20
Mammatus are pouch-like
cloud structures and a rare
example of clouds in sinking
Sometimes very ominous in
clouds are harmless
do not mean that a tornado
is about to form; a
In fact, mammatus are usually
seen after the worst of a
thunderstorm has passed.
Aug-12 Quartermaster 15 - Weather 21
Orographic clouds - Cap clouds
Form when air containing water vapor is uplifted on the windward
slide of the slope and reaches saturation producing liquid water
cloud droplets and a cloud which can "cap" the summit.
Aug-12 Quartermaster 15 - Weather 22
Orographic clouds - Lenticular clouds
Lens-shaped clouds that can result
from strong wind flow over rugged
Sometimes stack up like pancakes in
The strong flow produces a distinct up
and down wavelike pattern on the lee
side of the mountain or large hill and
the lenticular clouds tend to form at the
peaks of these waves.
They sometimes are very round and
the edges are so well defined that they
resemble flying saucers.
Often placed into the middle cloud
category since they are most common
at those altitudes.
Aug-12 Quartermaster 15 - Weather 23
When cloud particles become too heavy to remain
suspended in the air, they fall to the earth as
Precipitation occurs in a variety of forms:
Rain and Hail
Aug-12 Quartermaster 15 - Weather 24
Cloud Type SW W NW N NE E SE S
Cirrus Good Weather Precipitation in 20 to 30 hours
Cirrocumulus Overcast Skies Precipitation in 15 to 25 hours
Cirrostratus Overcast Skies Precipitation in 15 to 25 hours
Altocumulus Overcast Skies Precipitation in 15 to 20 hours
Altostratus Overcast Skies Precipitation in 10 to 20 hours
Cumulus Fair Weather Watch closely
Stratocumulus Overcast Skies Threatening Weather
Stratus Drizzle or Overcast Skies Heavy Precipitation
Cumulonimbus Precipitation likely and soon usually from SW to NW
Nimbostratus Precipitation of short duration Precipitation of long duration
Aug-12 Quartermaster 15 - Weather 25
A device for measuring the velocity or the pressure of the
Derived from the Greek word, anemos, meaning wind.
also called a wind vane, a movable device for showing the
direction of the wind.
Often are in the shape of cockerels or arrows, but a
multitude of designs have been used
Aug-12 Quartermaster 15 - Weather 26
An instrument used to measure atmospheric pressure by using water, air, or
mercury or springs.
Pressure tendency can forecast short term changes in the weather.
Numerous measurements of air pressure are used within surface weather
analysis to help find surface troughs, high pressure systems, and frontal
a device that measures temperature or temperature gradient, using a variety of
derived from thermo from the Greek for heat and meter from Gree, meaning to
has two important elements,
the temperature sensor (e.g. the bulb on a mercury thermometer) in which some
physical change occurs with temperature,
plus some means of converting this physical change into a value (e.g. the scale on
a mercury thermometer)
Aug-12 Quartermaster 15 - Weather 27
Hygrometers are instruments used for measuring humidity.
A simple form of a hygrometer
consists of two thermometers, one of which includes a dry bulb and the
other of which includes a bulb that is kept wet to measure wet-bulb
Evaporation from the wet bulb lowers the temperature, so that the wet-
bulb thermometer usually shows a lower temperature than that of the
dry-bulb thermometer, which measures dry-bulb temperature.
Relative humidity is computed from the ambient temperature as shown
by the dry-bulb thermometer and the difference in temperatures as
shown by the wet-bulb and dry-bulb thermometers.
Aug-12 Quartermaster 15 - Weather 28