CHAPTER 4
FRONTS AND STORMS
Mariners have much to fear when they
are threatened by a severe storm.
A gale can strain rigging, spring seams,
bend plates, smash equipment, and tear
loose topside equipment.
The prudent mariner will maneuver to
stay clear of storms whenever possible.
An experienced mariner should be able to
see when weather disturbances are coming.
Today’s radio communications provide
regular weather summaries.
The mariner at sea
will carefully plot
storm information
relative to the
vessel's position
and proposed
track.
Fronts develop when air masses of
different temperatures collide. Fronts
are weather systems that are sometimes
called wav...
Wave

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

A rapid and considerable drop in
temperature, usually affecting a
large area
Usually the colder of
two air masses, being
heavier, predominates
and forces the
warmer air upward.
Predominate

To be stronger or leading element
or force
A cold front displaces the warm air
ahead of it upward.
Cold Front

The zone separating two air masses,
of which the cooler, denser mass is
advancing and replacing the warmer
A warm front moves upward over a
retreating cold air mass.
Warm Front

A transition zone between a mass
of warm air and the colder air it is
replacing
WARM
FRONT



COLD
FRONT
When a cold front overtakes a warm front it
pushes the warm air up and converges with
a cooler mass ahead of the warm fron...
Converge

To come together
Occluded Front




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

A composite front formed when a
cold front overtakes a warm front
and forces it aloft
Frontal weather disturbances are
normally 15 - 50 miles wide for a cold
front and up to 300 miles wide for a
warm front.
The point where the cold and warm
fronts converge is frequently the center
of a low-pressure area.
Fronts develop when air masses
of different __________ collide.

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

a.   pressure
b.   size
c.   speed
d.   temperature
90°N
         Polar Easterlies

                               60°N

       Arctic Frontal Zone
                          ...
The convergence of                    90°N
the northeast trade              Polar Easterlies

winds of the                ...
Intertropical Convergence Zone
              (ITCZ)

Situated or occurring between the
tropic of Cancer and the tropic of
...
The ITCZ is a storm development area
that frequently breeds squalls.
Squall

A sudden, violent windstorm, often
accompanied by intense rain, snow,
or sleet
90°N
                               Polar Easterlies
                                                     60°N
The Arctic ...
Arctic Frontal Zone

Located at or near the North Pole
and pertaining to the division
between dissimilar air masses
The Polar Frontal Zone              90°N
                               Polar Easterlies
is formed by the                 ...
Polar Frontal Zone

A variable frontal zone of middle
latitudes separating air masses of
polar and tropical regions
Temperate

Moderate in respect to temperature;
not subject to prolonged extremes
of hot or cold weather
The three primary frontal zones are the
Intertropical Convergence Zone, the
Arctic Frontal Zone, and the _________
Frontal...
The three primary frontal zones are the
Intertropical Convergence Zone, the
Arctic Frontal Zone, and the _________
Frontal...
You first notice a cold front when the
sky darkens to the north and west.
Soon thereafter, the ceiling lowers and
rain beg...
A rapidly moving
cold front may
move as much as
700 miles in one
day.
Passage of a cold front is usually
marked by:

•   Wind shift
•   Drop in temperature
•   Rise in pressure
•   Rapid clear...
Squall lines often
precede a cold
front. They are often
violent, causing
flash floods from
downpours,
cloudbursts, and
ext...
What type of clouds often precede a cold
front?

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

a.   Cirrus
b.   Cumulonimbus
c.   Nimbostratus
d.   Stratus
Cirrus clouds in parallel precede a
warm front, followed by cirrostratus,
altostratus, nimbostratus, and finally
stratus c...
Visibility is poor in advance of a warm
front. Frequently fog forms, and steady
rain or drizzle prevails. Thunderstorms
ma...
Passage of a warm front is usually
marked by:
• Wind shift
• Rise in temperature
• Pressure remains steady or gradually
  ...
Warm fronts normally move less than
15 miles per hour. Cloud sequences may
begin 48 hours in advance and occur
1,000 miles...
A warm front will be preceded by what
type of clouds?

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

a.   Cirrus
b.   Cumulus
c.   Nimbus
d.   Stratus
An occluded front is an unstable frontal
cyclonic rotation with a rapidly moving
cold front.
In a cold front type of occlusion, the cold
front that remains on the surface is called
the occluded front and the warm fr...
Upper Front

A warm front raised aloft by a cold
front or a cold front raised aloft by
a warm front
Occlusions of this type:
• Occur on eastern portions of continents
• Have heavy frontal precipitation with
  thunderstorms...
Warm front occlusion
                                Warm Air
           Cold front aloft

Cold Front                    W...
Occlusions of this type:
• Occur chiefly in the Pacific Northwest
• Cause severe icing and precipitation
With occluded fronts, the front that is
raised or lifted is called the ________
front.

a.   Dominate
b.   Occluded
c.   S...
With occluded fronts, the front that is
raised or lifted is called the ________
front.

a.   Dominate
b.   Occluded
c.   S...
Thunderstorms occur within clouds with
vertical development, such as cumulus
and cumulonimbus. They are of short
duration ...
Thunderstorm

A transient storm of lightning and
thunder, usually with rain and
gusty winds, sometimes with hail
or tornad...
The first stage of a
thunderstorm is the
cumulus stage
characterized by an
updraft of warm
moist air into the
atmosphere, ...
The second stage,
called the mature
stage of
thunderstorm
development, is
characterized by
both updrafts and
downdrafts wi...
The final stage is
called the
dissipating or anvil
stage. The entire
lower portion of the
cloud becomes a
downdraft and hi...
Dissipate

To scatter in various directions;
disperse; dispel
Anvil

A cloud with a flat top, shaped like
an anvil
There are many weather phenomena
within thunderstorms. Rain is found in
all thunderstorms. Hail and snow may
also form and...
Phenomena

Something that is impressive or
extraordinary
A thunderstorm is most turbulent in
the area of heaviest precipitation.
Icing will often occur just above the
freezing lev...
Turbulent

Being in a state of agitation or
tumult; disturbed
Thunderstorms usually occur with what
types of clouds?

a.   Cirrus and Cirrostratus
b.   Cumulus and cumulonimbus
c.   Ni...
Thunderstorms usually occur with what
types of clouds?

a.   Cirrus and Cirrostratus
b.   Cumulus and cumulonimbus
c.   Ni...
The leading gust of wind, sometimes
called a microburst, is one of a
thunderstorm’s dangers.
Microburst

An intense, localized downdraft
of air that spreads on the ground,
causing rapid changes in wind
direction and...
The speed of the first gust is usually the
highest and can blow in any direction, even
opposite of the wind pushing the st...
Wind Shear

A condition, dangerous to aircraft,
in which the speed or direction of
the wind changes abruptly
Surging air currents
in the thunderhead
cloud create static
electricity, the
source of lightning.
Lightning

A brilliant electric spark discharge
in the atmosphere, occurring within
a thundercloud, between clouds, or
bet...
The process is not completely understood.
Positive charges develop near the top of the
cloud, and negative particles accum...
Lightning may flash within a cloud.
Lightning may jump from cloud to cloud.
Lightning may jump from cloud to
ground or ground to cloud.
Lightning occurs in two steps:

• A leader of electrified (ionized) air runs
  between two oppositely charged
  regions
• ...
Brush Fire




   Satellite Antenna Dish
Lightning generates terrific
heat, causing an explosive
expansion of glowing hot
...
Lightning follows the shortest route
between a cloud and ground. High points
are most likely to be struck. Do not stand
un...
Lightning also follows
the easiest route to
 ground after striking.
It is very unwise
to be on or near
bodies of water
during a
thunderstorm.
Mountainous areas,
especially with
crevices or rushing
mountain streams
should be avoided
during
thunderstorms.
Crevice

A crack forming an opening; cleft;
rift; fissure
A fundamental rule for pilots is never to
fly under or through a
thunderstorm. But if
unavoidable, it should
be penetrated...
A gust in a thunderstorm that blows in
opposition to the surface wind can result
in _________.

a.   a tornado
b.   an occ...
A gust in a thunderstorm that blows in
opposition to the surface wind can result
in _________.

a.   a tornado
b.   an occ...
The most intense and violent of
localized storms is the tornado.
Tornado

A localized, violently destructive
windstorm occurring over land,
especially in the Middle West, and
characterize...
Vortex




Tornadoes are very small in diameter,
usually 300 to 400 feet; but may continue
on an erratic path for more tha...
Vortex

A whirling mass of air in the form of
a visible column or spiral
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 t...
A tornado forms as a funnel cloud on
the forward edge of a fully developed
cumulonimbus cloud. When the funnel
touches the...
If a funnel forms over water, it is called
a waterspout. It is laden with mist and
spray.
A dust devil is a small whirlwind,
common in dry regions on hot, calm
afternoons made visible by dust, debris,
and sand it...
1981 - 1990 F1 through F5 Tornados




The Midwestern United States is the
most tornado-ravaged area of the world.
The extreme low pressure in the vortex
of a tornado causes homes to explode
outward from the normal pressure of
air trappe...
Where are tornadoes most common?

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

a.   Doldrums
b.   Equator
c.   Polar Frontal Zone
d.   Temperate zone
Tropical cyclones are subdivided into
three categories:

• Tropical depression – maximum wind
  less than 34 knots

• Trop...
Cyclone

A large scale atmospheric wind-and-
pressure system characterized by low
pressure at its center and by circular
w...
Large tropical
cyclones occur
in many places
in the world and
are called by
various names.
North
          Pacific Ocean                       North
                                         Atlantic Ocean
Typhoon
...
Hurricane

A violent, tropical, cyclonic storm
of the western North Atlantic,
having wind speeds of or in excess
of 64 kno...
Typhoon

A tropical cyclone or hurricane of
the western Pacific area and the
China seas
Willy-willies

A severe tropical typhoon off
Australia
Baguios

A severe tropical typhoon off the
Philippines
ALBERTO
                       BERYL
                       CHRIS
                       DEBBY
                       ERNE...
The velocities of hurricanes are
much less than tornadoes, but their
destruction covers hundreds of miles
and last much lo...
Hurricanes and typhoons were named
after women only until what year?

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

a.   1964
b.   1974
c.   1978
d.   1988
The birth of a
hurricane often
occurs near the
equator. They
never occur
right on the
equator because
the twisting
Corioli...
Hurricanes:

• Vary in diameter from 60 - 1,000 miles

• Have moderate winds on the outside
  and velocities as high as 17...
At the center of a hurricane is the eye
of the storm that averages 14 miles in
diameter. This area is calm, with light
win...
Eye

The approximate circular region
of relatively light winds and fair
weather found at the center of a
hurricane
The Atlantic hurricane starts
as a tropical low, grows into a storm,
and matures into a hurricane.
When it curves
to the northeast it
comes over cooler
waters and cooler
air, reduces internal
action and dissipates,
eventu...
• Winds increase from the outer limits to
  the edge of the eye
• Temperature rises and humidity falls
  at the center
• P...
Quadrant

One quarter of a circle; an arc of
90 degrees
Hurricanes are usually associated with
great wind-caused tides called storm
surges that inundate the land areas and
cause ...
Inundate

To flood; cover or overspread with
water; deluge
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
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
Hurricanes occur most frequently in
September and October but can happen
anytime from June to December. Heavy
rains and ti...
With less frequency, but often with
greater violence, are hurricanes that
originate in the Gulf of Mexico. They
can wreak ...
Tropical
Cyclone
 Track
When a typhoon veers into the Asian
continent, it is usually accompanied by
significant storm surge.
Bay of
                  Bengal


Just as a hurricane may move into the
Gulf of Mexico, a typhoon may sweep
south of Indon...
In probably the greatest natural catastrophe
of history, a typhoon swept over the Bay of
Bengal in 1737. The storm pushed ...
Catastrophe

A sudden and widespread disaster
A hurricane hit Galveston, Texas
in 1900, killing 6,000.
A hurricane hit New England in 1938,
killing 600 and causing damage in
excess of $250 million.
The boardwalk at Atlantic City, New Jersey
has been swept away several times.
The city of Belize was totally destroyed
by a hurricane in the late 1960s.
One of the strongest hurricanes ever recorded
in the Western Hemisphere was Hurricane
Gilbert that hit the Yucatan Peninsu...
One of Florida’s greatest disasters
happened in 1992 when Hurricane
Andrew crossed the Florida Peninsula.
Hurricane Katrina caused major damage
to the New Orleans area. Levies broke
that caused major flooding of the city.
Hurricane
 Katrina
Devastation
of Hurricane
   Katrina
DANGEROUS
                    SEMI-CIRCLE


 NAVIGABLE
SEMI-CIRCLE
              Northern Hemisphere


              South...
navigable           dangerous
           semicircle          semicircle



                    storm
                   di...
Maneuvering a vessel in a hurricane
consists of determining whether she is in,
or approaching, the dangerous semicircle,
a...
If you face in the same direction a
hurricane in the Northern Hemisphere is
moving, winds in the left semicircle are
calle...
If you face in the same direction a
hurricane in the Northern Hemisphere is
moving, winds in the left semicircle are
calle...
Flags and pennants
hoisted at the National
Weather Service and
other shore stations
indicate the presence
or forecast pres...
SMALL
                    CRAFT
                   WARNING



One red pennant displayed by day,
and a red light over a whi...
GALE
                    WARNING




Two red pennants by day, and a white
light above a red light at night, indicate
winds...
STORM
                       WARNING




A single square red flag with a black center
displayed by day, and two red lights...
HURRICANE
                 WARNING




Two square red flags with black centers
by day and a white light between two
red li...
Which storm warning signal is composed
of a white light above a red light at night?

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

a.   Gale
b.   Hurricane
c.   Small c...
The U.S. Hurricane
Warning System
was set up in 1938.
Reconnaissance airplanes equipped
with radar and weather instruments are
sent to scout suspected storm areas
and to monito...
Reconnaissance

A general examination or survey
of a region
In recent years,
weather satellites
supplemented by
reconnaissance
aircraft are used
to supply data
on hurricanes.
Bulletins are issued every couple of
hours to warn all who are in danger to
prepare for the storm by securing their
proper...
In what year was the U.S. Hurricane
Warning System set up?

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

a.   1938
b.   1947
c.   1966
d.   1974
Q.1. What are weather fronts?
Q.1. What are weather fronts?


A.1. The boundary between air
     masses with different
     characteristics, e.g., moist...
Q.2. What causes fronts to form
     wave-like patterns?
Q.2. What causes fronts to form
     wave-like patterns?


A.2. The friction of the ground and
     circular motion of the...
Q.3. How far may a frontal wave
     extend?
Q.3. How far may a frontal wave
     extend?


A.3. For hundreds of miles along
     the surface
Q.4. How far do frontal weather
     disturbances extend for cold
     and warm fronts?
Q.4. How far do frontal weather
     disturbances extend for cold
     and warm fronts?


A.4. Generally from 15 - 50 mile...
Q.5. What are the primary frontal
     zones around the world?
Q.5. What are the primary frontal
     zones around the world?


A.5. a. The Intertropical
        Convergence Zone
     b...
Q.6. What forms the Intertropical
     Convergence Zone (ITCZ)?
Q.6. What forms the Intertropical
     Convergence Zone (ITCZ)?


A.6. The convergence of the trade
     winds from the No...
Q.7. What happens to the Arctic
     Frontal Zone during the
     summer?
Q.7. What happens to the Arctic
     Frontal Zone during the
     summer?


A.7. It moves to the north and
     disappears
Q.8. What is the significance of the
     Polar Frontal Zone?
Q.8. What is the significance of the
     Polar Frontal Zone?


A.8. It has the greatest influence on
     the weather in ...
Q.9. What kind of weather is
     produced in front of a fast-
     moving cold front?
Q.9. What kind of weather is
     produced in front of a fast-
     moving cold front?


A.9. Violent thunderstorms and ra...
Q.10. Where do tornadoes develop?
Q.10. Where do tornadoes develop?


A.10. Generally within a squall line
      or severe thunderstorm in
      front of a ...
Q.11. What is a tropical cyclone?
Q.11. What is a tropical cyclone?


A.11. A low pressure circulation
      that forms in the tropics
Q.12. What are the three categories
      of tropical cyclones?
Q.12. What are the three categories
      of tropical cyclones?


A.12. a. Tropical depressions
      b. Tropical storms
 ...
Q.13. Where do hurricanes form?
Q.13. Where do hurricanes form?


A.13. Over the tropical water of the
      Atlantic and the Pacific (out to
      the In...
Q.14. How far in advance of a
      hurricane can the effects be
      seen?
Q.14. How far in advance of a
      hurricane can the effects be
      seen?


A.14. Clouds, weather and swells
      can ...
Q.15. When do most hurricanes
      occur?
Q.15. When do most hurricanes
      occur?


A.15. June to December is
      hurricane season, but most
      hurricanes o...
Q.16. Which is the most dangerous
      semicircle of a hurricane?
Q.16. Which is the most dangerous
      semicircle of a hurricane?


A.16. The right semicircle (when
      facing in the ...
Q.17. What warnings are displayed
      to indicate the presence or
      forecast of unfavorable or
      dangerous winds?
Q.17. What warnings are displayed
      to indicate the presence or
      forecast of unfavorable or
      dangerous winds...
Q.18. What countries are associated
      with (a) typhoons and
      (b) baguios?
Q.18. What countries are associated
      with (a) typhoons and
      (b) baguios?


A.18. a. China
      b. The Philippin...
Q.19. What information on a storm
      does a weather forecast
      consist of?
Q.19. What information on a storm
      does a weather forecast
      consist of?


A.19. Probable path, intensity, and
  ...
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NS2 3.4 Fronts and Storms

  1. 1. CHAPTER 4 FRONTS AND STORMS
  2. 2. Mariners have much to fear when they are threatened by a severe storm.
  3. 3. A gale can strain rigging, spring seams, bend plates, smash equipment, and tear loose topside equipment.
  4. 4. The prudent mariner will maneuver to stay clear of storms whenever possible.
  5. 5. An experienced mariner should be able to see when weather disturbances are coming.
  6. 6. Today’s radio communications provide regular weather summaries.
  7. 7. The mariner at sea will carefully plot storm information relative to the vessel's position and proposed track.
  8. 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. 9. Wave A body of air moving, resembling a wave of the sea; usually associated with hot or cold weather
  10. 10. Cold Wave A rapid and considerable drop in temperature, usually affecting a large area
  11. 11. Usually the colder of two air masses, being heavier, predominates and forces the warmer air upward.
  12. 12. Predominate To be stronger or leading element or force
  13. 13. A cold front displaces the warm air ahead of it upward.
  14. 14. Cold Front The zone separating two air masses, of which the cooler, denser mass is advancing and replacing the warmer
  15. 15. A warm front moves upward over a retreating cold air mass.
  16. 16. Warm Front A transition zone between a mass of warm air and the colder air it is replacing
  17. 17. WARM FRONT COLD FRONT
  18. 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. 19. Converge To come together
  20. 20. Occluded Front The convergent frontal mass is called an occluded front.
  21. 21. Occluded Front A composite front formed when a cold front overtakes a warm front and forces it aloft
  22. 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. 23. The point where the cold and warm fronts converge is frequently the center of a low-pressure area.
  24. 24. Fronts develop when air masses of different __________ collide. a. pressure b. size c. speed d. temperature
  25. 25. Fronts develop when air masses of different __________ collide. a. pressure b. size c. speed d. temperature
  26. 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. 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. 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. 29. The ITCZ is a storm development area that frequently breeds squalls.
  30. 30. Squall A sudden, violent windstorm, often accompanied by intense rain, snow, or sleet
  31. 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. 32. Arctic Frontal Zone Located at or near the North Pole and pertaining to the division between dissimilar air masses
  33. 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. 34. Polar Frontal Zone A variable frontal zone of middle latitudes separating air masses of polar and tropical regions
  35. 35. Temperate Moderate in respect to temperature; not subject to prolonged extremes of hot or cold weather
  36. 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. 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. 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. 39. A rapidly moving cold front may move as much as 700 miles in one day.
  40. 40. Passage of a cold front is usually marked by: • Wind shift • Drop in temperature • Rise in pressure • Rapid clearing
  41. 41. Squall lines often precede a cold front. They are often violent, causing flash floods from downpours, cloudbursts, and extremely turbulent winds.
  42. 42. What type of clouds often precede a cold front? a. Cirrus b. Cumulonimbus c. Nimbostratus d. Stratus
  43. 43. What type of clouds often precede a cold front? a. Cirrus b. Cumulonimbus c. Nimbostratus d. Stratus
  44. 44. Cirrus clouds in parallel precede a warm front, followed by cirrostratus, altostratus, nimbostratus, and finally stratus clouds.
  45. 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. 46. Passage of a warm front is usually marked by: • Wind shift • Rise in temperature • Pressure remains steady or gradually drops • Gradual clearing
  47. 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. 48. A warm front will be preceded by what type of clouds? a. Cirrus b. Cumulus c. Nimbus d. Stratus
  49. 49. A warm front will be preceded by what type of clouds? a. Cirrus b. Cumulus c. Nimbus d. Stratus
  50. 50. An occluded front is an unstable frontal cyclonic rotation with a rapidly moving cold front.
  51. 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. 52. Upper Front A warm front raised aloft by a cold front or a cold front raised aloft by a warm front
  53. 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. 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. 55. Occlusions of this type: • Occur chiefly in the Pacific Northwest • Cause severe icing and precipitation
  56. 56. With occluded fronts, the front that is raised or lifted is called the ________ front. a. Dominate b. Occluded c. Shear d. Upper
  57. 57. With occluded fronts, the front that is raised or lifted is called the ________ front. a. Dominate b. Occluded c. Shear d. Upper
  58. 58. Thunderstorms occur within clouds with vertical development, such as cumulus and cumulonimbus. They are of short duration and difficult to forecast.
  59. 59. Thunderstorm A transient storm of lightning and thunder, usually with rain and gusty winds, sometimes with hail or tornadoes
  60. 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. 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. 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. 63. Dissipate To scatter in various directions; disperse; dispel
  64. 64. Anvil A cloud with a flat top, shaped like an anvil
  65. 65. There are many weather phenomena within thunderstorms. Rain is found in all thunderstorms. Hail and snow may also form and fall.
  66. 66. Phenomena Something that is impressive or extraordinary
  67. 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. 68. Turbulent Being in a state of agitation or tumult; disturbed
  69. 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. 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. 71. The leading gust of wind, sometimes called a microburst, is one of a thunderstorm’s dangers.
  72. 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. 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. 74. Wind Shear A condition, dangerous to aircraft, in which the speed or direction of the wind changes abruptly
  75. 75. Surging air currents in the thunderhead cloud create static electricity, the source of lightning.
  76. 76. Lightning A brilliant electric spark discharge in the atmosphere, occurring within a thundercloud, between clouds, or between clouds and the ground
  77. 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. 78. Lightning may flash within a cloud.
  79. 79. Lightning may jump from cloud to cloud.
  80. 80. Lightning may jump from cloud to ground or ground to cloud.
  81. 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. 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. 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. 84. Lightning also follows the easiest route to ground after striking.
  85. 85. It is very unwise to be on or near bodies of water during a thunderstorm.
  86. 86. Mountainous areas, especially with crevices or rushing mountain streams should be avoided during thunderstorms.
  87. 87. Crevice A crack forming an opening; cleft; rift; fissure
  88. 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. 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. 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. 91. The most intense and violent of localized storms is the tornado.
  92. 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. 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. 94. Vortex A whirling mass of air in the form of a visible column or spiral
  95. 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. 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. 97. If a funnel forms over water, it is called a waterspout. It is laden with mist and spray.
  98. 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. 99. 1981 - 1990 F1 through F5 Tornados The Midwestern United States is the most tornado-ravaged area of the world.
  100. 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. 101. Where are tornadoes most common? a. Doldrums b. Equator c. Polar Frontal Zone d. Temperate zone
  102. 102. Where are tornadoes most common? a. Doldrums b. Equator c. Polar Frontal Zone d. Temperate zone
  103. 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. 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. 105. Large tropical cyclones occur in many places in the world and are called by various names.
  106. 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. 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. 108. Typhoon A tropical cyclone or hurricane of the western Pacific area and the China seas
  109. 109. Willy-willies A severe tropical typhoon off Australia
  110. 110. Baguios A severe tropical typhoon off the Philippines
  111. 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. 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. 113. Hurricanes and typhoons were named after women only until what year? a. 1964 b. 1974 c. 1978 d. 1988
  114. 114. Hurricanes and typhoons were named after women only until what year? a. 1964 b. 1974 c. 1978 d. 1988
  115. 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. 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. 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. 118. Eye The approximate circular region of relatively light winds and fair weather found at the center of a hurricane
  119. 119. The Atlantic hurricane starts as a tropical low, grows into a storm, and matures into a hurricane.
  120. 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. 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. 122. Quadrant One quarter of a circle; an arc of 90 degrees
  123. 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. 124. Inundate To flood; cover or overspread with water; deluge
  125. 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. 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. 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. 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. 129. Tropical Cyclone Track
  130. 130. When a typhoon veers into the Asian continent, it is usually accompanied by significant storm surge.
  131. 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. 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. 133. Catastrophe A sudden and widespread disaster
  134. 134. A hurricane hit Galveston, Texas in 1900, killing 6,000.
  135. 135. A hurricane hit New England in 1938, killing 600 and causing damage in excess of $250 million.
  136. 136. The boardwalk at Atlantic City, New Jersey has been swept away several times.
  137. 137. The city of Belize was totally destroyed by a hurricane in the late 1960s.
  138. 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. 139. One of Florida’s greatest disasters happened in 1992 when Hurricane Andrew crossed the Florida Peninsula.
  140. 140. Hurricane Katrina caused major damage to the New Orleans area. Levies broke that caused major flooding of the city.
  141. 141. Hurricane Katrina
  142. 142. Devastation of Hurricane Katrina
  143. 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. 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. 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. 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. 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. 148. Flags and pennants hoisted at the National Weather Service and other shore stations indicate the presence or forecast presence of unfavorable winds.
  149. 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. 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. 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. 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. 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. 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. 155. The U.S. Hurricane Warning System was set up in 1938.
  156. 156. Reconnaissance airplanes equipped with radar and weather instruments are sent to scout suspected storm areas and to monitor hurricanes.
  157. 157. Reconnaissance A general examination or survey of a region
  158. 158. In recent years, weather satellites supplemented by reconnaissance aircraft are used to supply data on hurricanes.
  159. 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. 160. In what year was the U.S. Hurricane Warning System set up? a. 1938 b. 1947 c. 1966 d. 1974
  161. 161. In what year was the U.S. Hurricane Warning System set up? a. 1938 b. 1947 c. 1966 d. 1974
  162. 162. Q.1. What are weather fronts?
  163. 163. Q.1. What are weather fronts? A.1. The boundary between air masses with different characteristics, e.g., moisture, temperature, etc.
  164. 164. Q.2. What causes fronts to form wave-like patterns?
  165. 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. 166. Q.3. How far may a frontal wave extend?
  167. 167. Q.3. How far may a frontal wave extend? A.3. For hundreds of miles along the surface
  168. 168. Q.4. How far do frontal weather disturbances extend for cold and warm fronts?
  169. 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. 170. Q.5. What are the primary frontal zones around the world?
  171. 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. 172. Q.6. What forms the Intertropical Convergence Zone (ITCZ)?
  173. 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. 174. Q.7. What happens to the Arctic Frontal Zone during the summer?
  175. 175. Q.7. What happens to the Arctic Frontal Zone during the summer? A.7. It moves to the north and disappears
  176. 176. Q.8. What is the significance of the Polar Frontal Zone?
  177. 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. 178. Q.9. What kind of weather is produced in front of a fast- moving cold front?
  179. 179. Q.9. What kind of weather is produced in front of a fast- moving cold front? A.9. Violent thunderstorms and rain
  180. 180. Q.10. Where do tornadoes develop?
  181. 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. 182. Q.11. What is a tropical cyclone?
  183. 183. Q.11. What is a tropical cyclone? A.11. A low pressure circulation that forms in the tropics
  184. 184. Q.12. What are the three categories of tropical cyclones?
  185. 185. Q.12. What are the three categories of tropical cyclones? A.12. a. Tropical depressions b. Tropical storms c. Hurricanes (or typhoons)
  186. 186. Q.13. Where do hurricanes form?
  187. 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. 188. Q.14. How far in advance of a hurricane can the effects be seen?
  189. 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. 190. Q.15. When do most hurricanes occur?
  191. 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. 192. Q.16. Which is the most dangerous semicircle of a hurricane?
  193. 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. 194. Q.17. What warnings are displayed to indicate the presence or forecast of unfavorable or dangerous winds?
  195. 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. 196. Q.18. What countries are associated with (a) typhoons and (b) baguios?
  197. 197. Q.18. What countries are associated with (a) typhoons and (b) baguios? A.18. a. China b. The Philippines
  198. 198. Q.19. What information on a storm does a weather forecast consist of?
  199. 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

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