Bishop Kenny NJROTC Naval Science Two Lesson Fronts and Storms

1. CHAPTER 4
FRONTS AND STORMS

2. Mariners have much to fear when they
are threatened by a severe storm.

3. A gale can strain rigging, spring seams,
bend plates, smash equipment, and tear
loose topside equipment.

4. The prudent mariner will maneuver to
stay clear of storms whenever possible.

5. An experienced mariner should be able to
see when weather disturbances are coming.

6. Today’s radio communications provide
regular weather summaries.

7. The mariner at sea
will carefully plot
storm information
relative to the
vessel's position
and proposed
track.

8. Fronts develop when air masses of
different temperatures collide. Fronts
are weather systems that are sometimes
called waves, as in the term “cold wave.”

9. Wave
A body of air moving, resembling a
wave of the sea; usually associated
with hot or cold weather

10. Cold Wave
A rapid and considerable drop in
temperature, usually affecting a
large area

11. Usually the colder of
two air masses, being
heavier, predominates
and forces the
warmer air upward.

12. Predominate
To be stronger or leading element
or force

13. A cold front displaces the warm air
ahead of it upward.

14. Cold Front
The zone separating two air masses,
of which the cooler, denser mass is
advancing and replacing the warmer

15. A warm front moves upward over a
retreating cold air mass.

16. Warm Front
A transition zone between a mass
of warm air and the colder air it is
replacing

17. WARM
FRONT
COLD
FRONT

18. When a cold front overtakes a warm front it
pushes the warm air up and converges with
a cooler mass ahead of the warm front.
Upper Air Cumulonimbus
Flow
Warm Air
Cold Air Heavy
Precipitation
Cold Front

19. Converge
To come together

20. Occluded Front
The convergent frontal mass is called an
occluded front.

21. Occluded Front
A composite front formed when a
cold front overtakes a warm front
and forces it aloft

22. Frontal weather disturbances are
normally 15 - 50 miles wide for a cold
front and up to 300 miles wide for a
warm front.

23. The point where the cold and warm
fronts converge is frequently the center
of a low-pressure area.

24. Fronts develop when air masses
of different __________ collide.
a. pressure
b. size
c. speed
d. temperature

25. Fronts develop when air masses
of different __________ collide.
a. pressure
b. size
c. speed
d. temperature

26. 90°N
Polar Easterlies
60°N
Arctic Frontal Zone
30°N
Northeast Trade winds
0°
Intertropical Convergence Zone
Southeast Trade winds
30°S
Antarctic Frontal Zone
60°S
Polar Easterlies
90°S

27. The convergence of 90°N
the northeast trade Polar Easterlies
winds of the 60°N
Northern Arctic Frontal Zone
30°N
Hemisphere
and the Northeast Trade winds
southeast Intertropical Convergence Zone 0°
trade winds of Southeast Trade winds
the Southern 30°S
Hemisphere Antarctic Frontal Zone
cause a band of 60°S
unstable weather Polar Easterlies
called the Intertropical 90°S
Convergence Zone.

28. Intertropical Convergence Zone
(ITCZ)
Situated or occurring between the
tropic of Cancer and the tropic of
Capricorn; band of unstable weather
encircling the Earth

29. The ITCZ is a storm development area
that frequently breeds squalls.

30. Squall
A sudden, violent windstorm, often
accompanied by intense rain, snow,
or sleet

31. 90°N
Polar Easterlies
60°N
The Arctic Frontal
Zone develops Arctic Frontal Zone
30°N
between the
Northeast Trade winds
arctic air of the
0°
far north and Intertropical Convergence Zone
the polar Southeast Trade winds
maritime air of 30°S
Antarctic Frontal Zone
the North Atlantic
60°S
and Pacific Oceans. Polar Easterlies
90°S

32. Arctic Frontal Zone
Located at or near the North Pole
and pertaining to the division
between dissimilar air masses

33. The Polar Frontal Zone 90°N
Polar Easterlies
is formed by the 60°N
Polar Frontal Zone
convergence of
the air that Arctic Frontal Zone
30°N
flows toward Northeast Trade winds
the equator 0°
Intertropical Convergence Zone
from the Polar
Southeast Trade winds
Easterlies and
30°S
the Prevailing Antarctic Frontal Zone
Westerlies (the Polar Frontal Zone 60°S
temperate zones). Polar Easterlies
90°S

34. Polar Frontal Zone
A variable frontal zone of middle
latitudes separating air masses of
polar and tropical regions

35. Temperate
Moderate in respect to temperature;
not subject to prolonged extremes
of hot or cold weather

36. The three primary frontal zones are the
Intertropical Convergence Zone, the
Arctic Frontal Zone, and the _________
Frontal Zone.
a. Antarctic
b. Occluded
c. Polar
d. Subtropical

37. The three primary frontal zones are the
Intertropical Convergence Zone, the
Arctic Frontal Zone, and the _________
Frontal Zone.
a. Antarctic
b. Occluded
c. Polar
d. Subtropical

38. You first notice a cold front when the
sky darkens to the north and west.
Soon thereafter, the ceiling lowers and
rain begins.

39. A rapidly moving
cold front may
move as much as
700 miles in one
day.

40. Passage of a cold front is usually
marked by:
• Wind shift
• Drop in temperature
• Rise in pressure
• Rapid clearing

41. Squall lines often
precede a cold
front. They are often
violent, causing
flash floods from
downpours,
cloudbursts, and
extremely turbulent
winds.

42. What type of clouds often precede a cold
front?
a. Cirrus
b. Cumulonimbus
c. Nimbostratus
d. Stratus

43. What type of clouds often precede a cold
front?
a. Cirrus
b. Cumulonimbus
c. Nimbostratus
d. Stratus

44. Cirrus clouds in parallel precede a
warm front, followed by cirrostratus,
altostratus, nimbostratus, and finally
stratus clouds.

45. Visibility is poor in advance of a warm
front. Frequently fog forms, and steady
rain or drizzle prevails. Thunderstorms
may develop ahead of a warm front.

46. Passage of a warm front is usually
marked by:
• Wind shift
• Rise in temperature
• Pressure remains steady or gradually
drops
• Gradual clearing

47. Warm fronts normally move less than
15 miles per hour. Cloud sequences may
begin 48 hours in advance and occur
1,000 miles in advance of the front itself.

48. A warm front will be preceded by what
type of clouds?
a. Cirrus
b. Cumulus
c. Nimbus
d. Stratus

49. A warm front will be preceded by what
type of clouds?
a. Cirrus
b. Cumulus
c. Nimbus
d. Stratus

50. An occluded front is an unstable frontal
cyclonic rotation with a rapidly moving
cold front.

51. In a cold front type of occlusion, the cold
front that remains on the surface is called
the occluded front and the warm front that
is raised aloft is called the upper front.

52. Upper Front
A warm front raised aloft by a cold
front or a cold front raised aloft by
a warm front

53. Occlusions of this type:
• Occur on eastern portions of continents
• Have heavy frontal precipitation with
thunderstorms
• Are of less intensity than cold fronts

54. Warm front occlusion
Warm Air
Cold front aloft
Cold Front Warm Front
(Fast-moving) (Slow-moving)
Cool Air Cold Air
In a warm front type of occlusion, the warm
front that remains on the surface is called
the occluded front and the cold front that
is raised aloft is called the upper front.

55. Occlusions of this type:
• Occur chiefly in the Pacific Northwest
• Cause severe icing and precipitation

56. With occluded fronts, the front that is
raised or lifted is called the ________
front.
a. Dominate
b. Occluded
c. Shear
d. Upper

57. With occluded fronts, the front that is
raised or lifted is called the ________
front.
a. Dominate
b. Occluded
c. Shear
d. Upper

58. Thunderstorms occur within clouds with
vertical development, such as cumulus
and cumulonimbus. They are of short
duration and difficult to forecast.

59. Thunderstorm
A transient storm of lightning and
thunder, usually with rain and
gusty winds, sometimes with hail
or tornadoes

60. The first stage of a
thunderstorm is the
cumulus stage
characterized by an
updraft of warm
moist air into the
atmosphere, clouds
growing taller and
taller.

61. The second stage,
called the mature
stage of
thunderstorm
development, is
characterized by
both updrafts and
downdrafts within
the storm-producing
cloud. Rain drops
and hail form and
begin to fall.

62. The final stage is
called the
dissipating or anvil
stage. The entire
lower portion of the
cloud becomes a
downdraft and high
winds flatten the top
of the cloud. Rain
falls heavily, but the
storm dissipates in
a short time.

63. Dissipate
To scatter in various directions;
disperse; dispel

64. Anvil
A cloud with a flat top, shaped like
an anvil

65. There are many weather phenomena
within thunderstorms. Rain is found in
all thunderstorms. Hail and snow may
also form and fall.

66. Phenomena
Something that is impressive or
extraordinary

67. A thunderstorm is most turbulent in
the area of heaviest precipitation.
Icing will often occur just above the
freezing level, making this a very
hazardous area for aircraft.

68. Turbulent
Being in a state of agitation or
tumult; disturbed

69. Thunderstorms usually occur with what
types of clouds?
a. Cirrus and Cirrostratus
b. Cumulus and cumulonimbus
c. Nimbus and Nimbostratus
d. Stratus and Cirrostratus

70. Thunderstorms usually occur with what
types of clouds?
a. Cirrus and Cirrostratus
b. Cumulus and cumulonimbus
c. Nimbus and Nimbostratus
d. Stratus and Cirrostratus

71. The leading gust of wind, sometimes
called a microburst, is one of a
thunderstorm’s dangers.

72. Microburst
An intense, localized downdraft
of air that spreads on the ground,
causing rapid changes in wind
direction and speed, a localized
downburst

73. The speed of the first gust is usually the
highest and can blow in any direction, even
opposite of the wind pushing the storm.
Such conditions can cause wind shear.

74. Wind Shear
A condition, dangerous to aircraft,
in which the speed or direction of
the wind changes abruptly

75. Surging air currents
in the thunderhead
cloud create static
electricity, the
source of lightning.

76. Lightning
A brilliant electric spark discharge
in the atmosphere, occurring within
a thundercloud, between clouds, or
between clouds and the ground

77. The process is not completely understood.
Positive charges develop near the top of the
cloud, and negative particles accumulate in
the lower reaches. An electrical discharge
occurs when the strength of the charges
overcomes the resistance.

78. Lightning may flash within a cloud.

79. Lightning may jump from cloud to cloud.

80. Lightning may jump from cloud to
ground or ground to cloud.

81. Lightning occurs in two steps:
• A leader of electrified (ionized) air runs
between two oppositely charged
regions
• The second stroke is the one you see,
and causes the thunder when the
circuit is completed.

82. Brush Fire
Satellite Antenna Dish
Lightning generates terrific
heat, causing an explosive
expansion of glowing hot
air and producing the
audible thunder. Burns

83. Lightning follows the shortest route
between a cloud and ground. High points
are most likely to be struck. Do not stand
under trees during a thunderstorm.

84. Lightning also follows
the easiest route to
ground after striking.

85. It is very unwise
to be on or near
bodies of water
during a
thunderstorm.

86. Mountainous areas,
especially with
crevices or rushing
mountain streams
should be avoided
during
thunderstorms.

87. Crevice
A crack forming an opening; cleft;
rift; fissure

88. A fundamental rule for pilots is never to
fly under or through a
thunderstorm. But if
unavoidable, it should
be penetrated at
1/3 its height.

89. A gust in a thunderstorm that blows in
opposition to the surface wind can result
in _________.
a. a tornado
b. an occluded front
c. squalls
d. wind shear

90. A gust in a thunderstorm that blows in
opposition to the surface wind can result
in _________.
a. a tornado
b. an occluded front
c. squalls
d. wind shear

91. The most intense and violent of
localized storms is the tornado.

92. Tornado
A localized, violently destructive
windstorm occurring over land,
especially in the Middle West, and
characterized by a long, funnel
shaped cloud extending to the
ground and made visible by
condensation and debris

93. Vortex
Tornadoes are very small in diameter,
usually 300 to 400 feet; but may continue
on an erratic path for more than 100 miles.
Winds in the vortex may exceed 300 mph.

94. Vortex
A whirling mass of air in the form of
a visible column or spiral

95. The speed of a tornado moving over the
Earth may be 25 - 40 mph. The duration
at any given spot may be only seconds,
but the devastation can be almost total.

96. A tornado forms as a funnel cloud on
the forward edge of a fully developed
cumulonimbus cloud. When the funnel
touches the ground it is called a
tornado.

97. If a funnel forms over water, it is called
a waterspout. It is laden with mist and
spray.

98. A dust devil is a small whirlwind,
common in dry regions on hot, calm
afternoons made visible by dust, debris,
and sand it picks up from the ground.

99. 1981 - 1990 F1 through F5 Tornados
The Midwestern United States is the
most tornado-ravaged area of the world.

100. The extreme low pressure in the vortex
of a tornado causes homes to explode
outward from the normal pressure of
air trapped inside.

101. Where are tornadoes most common?
a. Doldrums
b. Equator
c. Polar Frontal Zone
d. Temperate zone

102. Where are tornadoes most common?
a. Doldrums
b. Equator
c. Polar Frontal Zone
d. Temperate zone

103. Tropical cyclones are subdivided into
three categories:
• Tropical depression – maximum wind
less than 34 knots
• Tropical storm – winds of 34 - 63
knots
• Hurricane or typhoon – winds of 64
knots and up

104. Cyclone
A large scale atmospheric wind-and-
pressure system characterized by low
pressure at its center and by circular
wind motion, counterclockwise in the
Northern Hemisphere, and clockwise in
the Southern Hemisphere

105. Large tropical
cyclones occur
in many places
in the world and
are called by
various names.

106. North
Pacific Ocean North
Atlantic Ocean
Typhoon
Baguios Hurricane
Hurricane
Cyclone
Willy-willies
Cyclone
South Indian
South Atlantic Ocean Ocean
Pacific Ocean
Hurricanes in the West Indies and on
the International Date Line, Typhoons
off China, Willy-willies off the west
coast of Australia, and Baguios off the
Philippines.

107. Hurricane
A violent, tropical, cyclonic storm
of the western North Atlantic,
having wind speeds of or in excess
of 64 knots (74 mph)

108. Typhoon
A tropical cyclone or hurricane of
the western Pacific area and the
China seas

109. Willy-willies
A severe tropical typhoon off
Australia

110. Baguios
A severe tropical typhoon off the
Philippines

111. ALBERTO
BERYL
CHRIS
DEBBY
ERNESTO
FLORENCE
GORDON. . .
Today, hurricanes and typhoons are
given alternating women's and men's
names. Before 1978, all of these
storms were named after women.

112. The velocities of hurricanes are
much less than tornadoes, but their
destruction covers hundreds of miles
and last much longer. It is the most
destructive of all weather phenomena.

113. Hurricanes and typhoons were named
after women only until what year?
a. 1964
b. 1974
c. 1978
d. 1988

114. Hurricanes and typhoons were named
after women only until what year?
a. 1964
b. 1974
c. 1978
d. 1988

115. The birth of a
hurricane often
occurs near the
equator. They
never occur
right on the
equator because
the twisting
Coriolis forces
are not there.

116. Hurricanes:
• Vary in diameter from 60 - 1,000 miles
• Have moderate winds on the outside
and velocities as high as 175 kts
(200 mph) toward the center

117. At the center of a hurricane is the eye
of the storm that averages 14 miles in
diameter. This area is calm, with light
winds and clear or moderately clear
skies with some drizzle.
Eye of
The Storm

118. Eye
The approximate circular region
of relatively light winds and fair
weather found at the center of a
hurricane

119. The Atlantic hurricane starts
as a tropical low, grows into a storm,
and matures into a hurricane.

120. When it curves
to the northeast it
comes over cooler
waters and cooler
air, reduces internal
action and dissipates,
eventually ending up as a gale or storm
over the North Atlantic or North Sea.

121. • Winds increase from the outer limits to
the edge of the eye
• Temperature rises and humidity falls
at the center
• Precipitation is heaviest in the right
front quadrant

122. Quadrant
One quarter of a circle; an arc of
90 degrees

123. Hurricanes are usually associated with
great wind-caused tides called storm
surges that inundate the land areas and
cause more damage than the wind or rain.

124. Inundate
To flood; cover or overspread with
water; deluge

125. Hurricanes are born in what type of air
mass?
a. Cold and dry
b. Cold and moist
c. Hot and dry
d. Hot and moist

126. Hurricanes are born in what type of air
mass?
a. Cold and dry
b. Cold and moist
c. Hot and dry
d. Hot and moist

127. Hurricanes occur most frequently in
September and October but can happen
anytime from June to December. Heavy
rains and tidal flooding are a danger.

128. With less frequency, but often with
greater violence, are hurricanes that
originate in the Gulf of Mexico. They
can wreak havoc throughout the Gulf
Coast and Mississippi Valley.

129. Tropical
Cyclone
Track

130. When a typhoon veers into the Asian
continent, it is usually accompanied by
significant storm surge.

131. Bay of
Bengal
Just as a hurricane may move into the
Gulf of Mexico, a typhoon may sweep
south of Indonesia into the Bay of Bengal
and then the coast of southern Asia.

132. In probably the greatest natural catastrophe
of history, a typhoon swept over the Bay of
Bengal in 1737. The storm pushed a 40-foot
surge of water inland, killing 300,000.

133. Catastrophe
A sudden and widespread disaster

134. A hurricane hit Galveston, Texas
in 1900, killing 6,000.

135. A hurricane hit New England in 1938,
killing 600 and causing damage in
excess of $250 million.

136. The boardwalk at Atlantic City, New Jersey
has been swept away several times.

137. The city of Belize was totally destroyed
by a hurricane in the late 1960s.

138. One of the strongest hurricanes ever recorded
in the Western Hemisphere was Hurricane
Gilbert that hit the Yucatan Peninsula in 1988,
killing 500 and rendering 500,000 homeless.

139. One of Florida’s greatest disasters
happened in 1992 when Hurricane
Andrew crossed the Florida Peninsula.

140. Hurricane Katrina caused major damage
to the New Orleans area. Levies broke
that caused major flooding of the city.

141. Hurricane
Katrina

142. Devastation
of Hurricane
Katrina

143. DANGEROUS
SEMI-CIRCLE
NAVIGABLE
SEMI-CIRCLE
Northern Hemisphere
Southern Hemisphere
Cyclonic winds rotate counterclockwise
in the Northern Hemisphere and
clockwise in the Southern Hemisphere.

144. navigable dangerous
semicircle semicircle
storm
direction
Winds in the right semicircle draw ships
into the path of the storm. Winds in the
left semicircle tend to drive the ship out
of the path of the storm.

145. Maneuvering a vessel in a hurricane
consists of determining whether she is in,
or approaching, the dangerous semicircle,
and if she is, finding the best method of
working out of the undesirable position.

146. If you face in the same direction a
hurricane in the Northern Hemisphere is
moving, winds in the left semicircle are
called the navigable semicircle.
a. True
b. False

147. If you face in the same direction a
hurricane in the Northern Hemisphere is
moving, winds in the left semicircle are
called the navigable semicircle.
a. True
b. False

148. Flags and pennants
hoisted at the National
Weather Service and
other shore stations
indicate the presence
or forecast presence
of unfavorable winds.

149. SMALL
CRAFT
WARNING
One red pennant displayed by day,
and a red light over a white light at
night, indicate winds of up to 33 knots
(38 mph) and sea conditions dangerous
to small craft are forecast.

150. GALE
WARNING
Two red pennants by day, and a white
light above a red light at night, indicate
winds ranging from 34-47 knots (39-54
mph) are forecast.

151. STORM
WARNING
A single square red flag with a black center
displayed by day, and two red lights at
night, indicate that winds of48 knots (55
mph) and above are forecast.

152. HURRICANE
WARNING
Two square red flags with black centers
by day and a white light between two
red lights at night, indicate winds 64
knots (74 mph) or greater are forecast.

153. Which storm warning signal is composed
of a white light above a red light at night?
a. Gale
b. Hurricane
c. Small craft
d. Storm

154. Which storm warning signal is composed
of a white light above a red light at night?
a. Gale
b. Hurricane
c. Small craft
d. Storm

155. The U.S. Hurricane
Warning System
was set up in 1938.

156. Reconnaissance airplanes equipped
with radar and weather instruments are
sent to scout suspected storm areas
and to monitor hurricanes.

157. Reconnaissance
A general examination or survey
of a region

158. In recent years,
weather satellites
supplemented by
reconnaissance
aircraft are used
to supply data
on hurricanes.

159. Bulletins are issued every couple of
hours to warn all who are in danger to
prepare for the storm by securing their
property and to evacuate.

160. In what year was the U.S. Hurricane
Warning System set up?
a. 1938
b. 1947
c. 1966
d. 1974

161. In what year was the U.S. Hurricane
Warning System set up?
a. 1938
b. 1947
c. 1966
d. 1974

162. Q.1. What are weather fronts?

163. Q.1. What are weather fronts?
A.1. The boundary between air
masses with different
characteristics, e.g., moisture,
temperature, etc.

164. Q.2. What causes fronts to form
wave-like patterns?

165. Q.2. What causes fronts to form
wave-like patterns?
A.2. The friction of the ground and
circular motion of the air in
front of and behind the fronts

166. Q.3. How far may a frontal wave
extend?

167. Q.3. How far may a frontal wave
extend?
A.3. For hundreds of miles along
the surface

168. Q.4. How far do frontal weather
disturbances extend for cold
and warm fronts?

169. Q.4. How far do frontal weather
disturbances extend for cold
and warm fronts?
A.4. Generally from 15 - 50 miles
wide in front of a cold front,
and up to 300 miles wide for
a warm front

170. Q.5. What are the primary frontal
zones around the world?

171. Q.5. What are the primary frontal
zones around the world?
A.5. a. The Intertropical
Convergence Zone
b. The Arctic Frontal Zone
c. The Polar Frontal Zone

172. Q.6. What forms the Intertropical
Convergence Zone (ITCZ)?

173. Q.6. What forms the Intertropical
Convergence Zone (ITCZ)?
A.6. The convergence of the trade
winds from the Northern and
Southern Hemispheres

174. Q.7. What happens to the Arctic
Frontal Zone during the
summer?

175. Q.7. What happens to the Arctic
Frontal Zone during the
summer?
A.7. It moves to the north and
disappears

176. Q.8. What is the significance of the
Polar Frontal Zone?

177. Q.8. What is the significance of the
Polar Frontal Zone?
A.8. It has the greatest influence on
the weather in the temperate
zone.

178. Q.9. What kind of weather is
produced in front of a fast-
moving cold front?

179. Q.9. What kind of weather is
produced in front of a fast-
moving cold front?
A.9. Violent thunderstorms and rain

180. Q.10. Where do tornadoes develop?

181. Q.10. Where do tornadoes develop?
A.10. Generally within a squall line
or severe thunderstorm in
front of a fast-moving cold
front

182. Q.11. What is a tropical cyclone?

183. Q.11. What is a tropical cyclone?
A.11. A low pressure circulation
that forms in the tropics

184. Q.12. What are the three categories
of tropical cyclones?

185. Q.12. What are the three categories
of tropical cyclones?
A.12. a. Tropical depressions
b. Tropical storms
c. Hurricanes (or typhoons)

186. Q.13. Where do hurricanes form?

187. Q.13. Where do hurricanes form?
A.13. Over the tropical water of the
Atlantic and the Pacific (out to
the International Date Line)

188. Q.14. How far in advance of a
hurricane can the effects be
seen?

189. Q.14. How far in advance of a
hurricane can the effects be
seen?
A.14. Clouds, weather and swells
can be seen up to 1,000 miles
in advance.

190. Q.15. When do most hurricanes
occur?

191. Q.15. When do most hurricanes
occur?
A.15. June to December is
hurricane season, but most
hurricanes occur in
September and October.

192. Q.16. Which is the most dangerous
semicircle of a hurricane?

193. Q.16. Which is the most dangerous
semicircle of a hurricane?
A.16. The right semicircle (when
facing in the direction the
hurricane is moving) because
the winds tend to draw ships
toward the worst weather

194. Q.17. What warnings are displayed
to indicate the presence or
forecast of unfavorable or
dangerous winds?

195. Q.17. What warnings are displayed
to indicate the presence or
forecast of unfavorable or
dangerous winds?
A.17. Small craft, gale, storm, and
hurricane warnings

196. Q.18. What countries are associated
with (a) typhoons and
(b) baguios?

197. Q.18. What countries are associated
with (a) typhoons and
(b) baguios?
A.18. a. China
b. The Philippines

198. Q.19. What information on a storm
does a weather forecast
consist of?

199. Q.19. What information on a storm
does a weather forecast
consist of?
A.19. Probable path, intensity, and
timely warning to all who may
be in danger