NAVIGATION TRAINING - PowerPoint PPT Presentation

Loading...

PPT – NAVIGATION TRAINING PowerPoint presentation | free to view - id: 71116-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

NAVIGATION TRAINING

Description:

Mean Sea Level Pressure ... In the northern hemisphere the circulation is anticlockwise around low pressure ... white horses. CANADIAN COAST GUARD AUXILIARY ... – PowerPoint PPT presentation

Number of Views:57
Avg rating:3.0/5.0
Slides: 58
Provided by: danrob
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: NAVIGATION TRAINING


1
NAVIGATION TRAINING Section 11 Weather
2
Table of Contents
  • Section 1 Types of Navigation
  • Section 2 Terrestial Coordinates
  • Section 3 Charts
  • Section 4 Compass
  • Section 5 Nautical Publications
  • Section 6 Navigational Aids

3
Table of Contents
  • Section 7 Buoyage
  • Section 8 Position Lines and Fixes
  • Section 9 Tides
  • Section 10 Currents
  • Section 11 Weather

4
Weather
5
Atmospheric Pressure
6
Atmospheric Pressure
  • The standard atmosphere (symbol atm) is a unit
    of pressure and is defined as being precisely
    equal to 101.325 kilopascals, 1013.25 millibars,
    or 29.92 inches of mercury.
  • The pressure gradient between a high pressure
    area and a low pressure area governs the strength
    of the wind, the wind blowing from high pressure
    to low pressure.
  • The greater the gradient the stronger the wind.

7
Atmospheric Pressure
  • An extreme example is the centre of a hurricane
    which can go as low as 94.8 kilopascals. The
    pressure gradient is huge, causing the winds to
    blow at 100 to 150 knots (nautical miles per
    hour).

8
Mean Sea Level Pressure
  • Where air masses meet, there are well-marked
    boundary zones called fronts. This is where most
    cloud and precipitation occurs.
  • In the northern hemisphere the circulation is
    anticlockwise around low pressure and clockwise
    around high pressure. The air flows almost
    parallel to the isobars but actually 10-15
    degrees inwards towards the low pressure.

9
Mean Sea Level Pressure
15 year average Mean Sea Level Pressure for June
July August 15 year average Mean Sea Level
Pressure for December January February
10
Global Circulation
  • The Earth rotates at a constant rate, and the
    winds blow, the transfer of momentum between
    Earth/atmosphere /Earth must be in balance and
    the angular velocity of the system maintained.
  • The atmosphere is rotating in the same direction
    as the Earth but westerly winds move faster and
    easterly winds move slower than the Earth's
    surface.

11
Global Circulation
  • Remember winds are identified by the direction
    they are coming from, not heading to!

12
Weather Fronts
  • Where air masses meet, there are well-marked
    boundary zones called fronts. This is where most
    cloud and precipitation occurs.
  • In the northern hemisphere the circulation is
    anticlockwise around low pressure and clockwise
    around high pressure. The air flows almost
    parallel to the isobars but actually 10-15
    degrees inwards towards the low pressure.

13
Weather Fronts
  • There are three types of front
  • 1. Warm front
  • 2. Cold front
  • 3. Occlusions and Occluded Fronts

14
Warm Fronts
  • When a warm moist air mass rises above a cold air
    mass, a warm front forms. The gradient of the
    front is very shallow. Warm fronts occur at the
    forward edge of a depression (a low-pressure
    system).

15
Warm Fronts
16
Warm Fronts
17
Cold Fronts
18
Cold Fronts
19
Cold Fronts
A cold front marks the advance of colder air
undercutting warm air. The gradient of the cold
front is steeper than that of a warm front, and
the rainfall is usually heavier. Thunderstorms
sometimes form along a cold front.
20
Occluded Fronts
  • Depressions and other frontal systems have a
    three-dimensional structure.
  • Most depressions weaken when the cold front
    catches up with the warm front and cuts it off
    from the ground.
  • If the cold front rises over the warm front, this
    is a warm occlusion.
  • If the cold front undercuts the warm front this
    is a cold occlusion.

21
Occluded Fronts
  • Weather systems grow mature and decay and as
    they do, new ones are created. This creates
    families of weather systems.

22
Wind
23
Wind
Wind is primarily the result of uneven heating of
the earths surface, which causes large hotter
areas and large cooler areas.
24
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 0 0-1
0-1 Calm Sea like a mirror
25
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 1 1-3
1-3 Light air Ripples with the
appearance of
scales are formed, but without
foam crests.
26
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 2 4-7
4-6 Light Breeze Small wavelets, still
short,
but more pronounced. Crests
have a glassy appearance
and do
not break.
27
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 3 8-12
7-10 Gentle Breeze Large wavelets. Crests
begin
to break. Foam of glassy
appearance. Perhaps scattered
white
horses.
28
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 4 13-18
11-16 Moderate Breeze Small waves, becoming
larger
fairly frequent white horses.
29
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 5 19-24
17-21 Fresh Breeze Moderate waves, taking
a more
pronounced long form many
white horses are formed.
Chance of
some spray.
30
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 6 25-31
22-27 Strong Breeze Large waves begin to
form the
white foam crests are more
extensive everywhere.
Probably
some spray.
31
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 7 32-38
28-33 Near Gale Sea heaps up and white
foam
from breaking waves begins to
be blown in streaks along
the
direction of the wind.
32
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 8 39-46
34-40 Gale Moderately high waves
of greater
length edges of crests begin to
break into
spindrift. The foam is
blown in well-marked streaks
along the
direction of the wind.
33
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 9 47-54
41-47 Severe Gale High waves. Dense
streaks of
foam along the direction of the
wind. Crests of
waves begin to
topple, tumble and roll over.
Spray may affect
visibility.
34
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 10 55-63
48-55 Storm Very high waves with
long over-
hanging crests. The resulting
foam, in great
patches, is blown
in dense white streaks along the
direction of
the wind. On the
whole the surface of the sea
takes on a white
appearance.
The 'tumbling' of the sea becomes
heavy and
shock-like. Visibility
affected.
35
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 11 64-72
56-63 Violent Storm Exceptionally high
waves (small
and medium-size ships might be for
a time lost to
view behind the
waves). The sea is completely
covered with
long white patches
of foam lying along the direction
of the
wind. Everywhere the edges
of the wave crests are blown
into
froth. Visibility affected.
36
Wind Force
FORCE EQUIVALENT SPEED DESCRIPTION
SPECIFICATIONS FOR USE AT SEA 10 m above
ground miles/hour knots 12 73-83
64-71 Hurricane The air is filled with
foam and
spray. Sea completely white with
driving spray
visibility very
seriously affected.
37
Sea Breeze
  • A sea-breeze (or onshore breeze) is a wind from
    the sea that develops over land near coasts.
  • It is formed by increasing temperature
    differences between the land (which heats up
    faster) and water (which warms slower) which
    create a pressure minimum over the land due to
    its relative warmth and forces higher pressure,
    cooler air from the sea to move inland.

38
Sea Breeze
It generally occurs in the afternoon.
39
Land Breeze
  • A land-breeze (or offshore breeze) is a wind to
    the sea that develops over land near coasts.
  • It is formed by increasing temperature
    differences between the land (which cools faster)
    and water (which cools slower) which create a
    pressure minimum over the sea due to its relative
    warmth and forces higher pressure, cooler air
    from the land to move offshore.

40
Land Breeze
It generally occurs in the very early morning.
41
Katabatic Winds
  • A katabatic wind, from the Greek word katabatikos
    meaning "going downhill", is a wind that blows
    down a topographic incline such as a hill,
    mountain, or glacier.
  • The cold form of katabatic wind originates in a
    cooling, either radiatively or through vertical
    motion, of air at the top of the mountain,
    glacier, or hill.

42
Katabatic Winds
  • Since the density of air increases with lower
    temperature, the air will flow downwards, warming
    adiabatically as it descends, but still remaining
    relatively cold.

43
Wind Force Sea State
  • The visible effects of the wind on the sea will
    be modified by the relative directions of wind
    and tide.
  • If the wind and tide are in opposite directions,
    then a larger chop will be created, giving the
    impression of the wind being stronger.
  • If wind and tide are in the same direction, the
    amount of sea will be reduced, giving the
    impression of the wind being less.

44
Sea and Swell
  • Sea is the effect of wind passing over the water
    locally.
  • Swell is only found in the open ocean and will be
    effects of weather systems, hundreds of miles
    away.

45
Fog
46
Fog
47
Fog
  • Fog is a cloud in contact with the ground.
  • Fog differs from other clouds only in that fog
    touches the surface of the Earth.
  • The same cloud that is not fog on lower ground
    may be fog where it contacts higher ground such
    as hilltops or mountain ridges.
  • Fog is distinct from mist only in its density.

48
Fog
  • Fog is defined as cloud which reduces visibility
    to less than 1 nautical mile, where as mist is
    that which reduces visibility to more than 1
    nautical mile.

49
Fog
  • Fog forms when water vapor in the air at the
    surface begins to condense into liquid water.
  • Fog normally occurs at a relative humidity of
    100. This can be achieved by either adding
    moisture to the air or dropping the ambient air
    temperature.
  • Fog can form at lower humidities, and fog can
    sometimes not form with relative humidity at 100.

50
Fog
  • Advection fog occurs when moist air passes over a
    cool surface by advection (wind) and is cooled.
    It is common as a warm front passes over an area
    significantly cooler. It's most common at sea
    when tropical air encounters cooler waters, or in
    areas of upwelling.

51
Upslope Fog
52
Other Types of Fog
53
Fog Slight Sea, Low Swell, Cloudy, Fine and
Clear
54
Precipitation
55
Orographic Rain
  • Orographic rain (or relief rain) is caused when
    the warm moisture-laden wind blowing in to the
    land from the sea encounters a natural barrier
    such as mountains. This forces the wind to rise.
  • With gain in altitude, the air expands
    dynamically due to a decrease in air pressure.
  • Due to this the wind experiences a decrease in
    temperature, which results in the increase of the
    relative humidity.

56
Orographic Rain
  • This causes condensation of the water vapour into
    water droplets to form clouds.
  • The relative humidity continues to increase until
    the dewpoint reaches the level of condensation,
    causing air to be saturated.
  • This height where the condensation occurs is
    called the level of condensation.
  • When the cloud droplets become too heavy to be
    suspended, rain falls.

57
Orographic Rain in Howe Sound
About PowerShow.com