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Navigation

NAU 102

Lesson 32

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Weather Instruments

The safety of crew, passengers, cargoand the ship itself is dependent on

making good weather decisions.

Weather has a significant impact on

every voyage.

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Weather Instruments

We are our own weather station at sea.

We must develop an accurate

forecast using data received from

shore and that we collect ourselves.

Youll learn how to make a forecast

in Meteorology.

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Duties of the Mate

At all times, be knowledgeable of the

current weather.

Wind direction and speed

Wave direction and heightVisibility

Trend of the barometer

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Duties of the Mate

At all times, be knowledgeable of the

weather forecast.

Obtain 24 hour forecast from

weather fax, messages, etc.

Interpret the forecast for your area.

When necessary, make your own

forecast.

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Weather Instruments

Satellites

Meteorological data is collected by:

Buoys

Ships (thats you)

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Duties of the Mate

Conduct marine surface weather

observations.

Make observations

Log observations

Transmit observations to National

Weather Service

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Duties of the Mate

Conduct marine surface weather

observations.

4 times each day

0000, 0600, 1200, 1800 GMT

Voluntary program

7000+ ships worldwide (600 US)

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Weather Observations

Data is collected and

formatted inaccordance with the

Marine Observers

Handbook.

http://www.nws.noaa.gov/om

/marine/handbk1.pdf

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Weather Instruments

Aneroid Barometer

Measures atmospheric pressure.

Air pressure exerts a crushing force

on a thin metal element.

Linkages move to a pointer to

indicate the pressure on a scale.

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Aneroid Barometer

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Aneroid Barometer

Must be properly adjusted.

(Usually done by a professional, often for free.)

Reading must be adjusted for elevation

to give pressure at sea level.

(Note: Mercurial Barometers must also be

corrected for latitude and temperature.)

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Barometers

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Weather Instruments

Barograph

A recording

barometer.

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Weather Instruments

Thermometer

Measures air

temperature.

You must be able to

convert betweenCelsius and

Fahrenheit scales.

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Temperature Conversions

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Temperature Conversions

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Weather Instruments

Hygrometer

Measures Relative Humidity and

Dew Point.

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Weather Instruments

Relative Humidity ratio of amount

of water vapor in the air to the

amount it could hold at the currenttemperature.

Dew Point the temperature atwhich water vapor will condense.

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Weather Instruments

Hygrometer

Most common type: sling

psychrometer.

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Sling Psychrometer

Two Thermometers: 1 wet, 1 dry

Temperature difference is noted.

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Sling Psychrometer

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Psychrometer

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Introduction to Navigation

Questions?