Meteorology Flashcards

1
Q

How would you predict fog?

A

To predict fog you will need a wet & dry hygrometer,

you compare the wet & dry temperature and enter the dewpoint table in NP100,

then you plot dewpoint against sea temperature to give you an indication of the likelyhood of fog.

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2
Q

What is a stevenson screen?

A

A shelter for met instruments against rain and direct heat, still allowing air to circulate around the instrument

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3
Q

What is advection fog?

A

Warm moist air over cold sea.
Advection fog is a type of fog formed when warm, moist air moves over a cooler surface, causing the air to cool and condense into fog.

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4
Q

What is radiation fog?

A

Fog that forms when the ground loses heat through radiation, cooling the air near the surface to its dew point, leading to condensation and fog formation.

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5
Q

What is sea breeze?

A

A sea breeze is a wind that blows from the sea to the land

Caused by the land heating up faster than the sea, creating a pressure difference.

Typically occurs in the afternoon when the temperature difference is greatest.

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6
Q

What is land breeze?

A

A land breeze is a wind that blows from the land to the sea

Caused by the land cooling down faster than the sea, creating a pressure difference.

Typically occurs at night or early morning.

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7
Q

What is katabatic winds?

A

Katabatic winds are gravity-driven winds that occur when cold, dense air descends from higher elevations to lower areas, typically forming at night.

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8
Q

What are the 4 big winds in the meds?

A

Mistral - Gulf of Lyon, is a type of katabatic wind, cold air descends from the Alps and flows toward the Mediterranean Sea.

Meltemi - Greece
Bernoulli - Gibraltar
Sirocco - from Africa

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9
Q

What is a anomometer?

A

Instrument to determine apparent wind direction & speed, placed eg on top of the mast

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10
Q

Sources of weather information?

A

Own ship, VHF, Navtex, local forecasts, SAT-C, weather fax, synoptic charts,

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11
Q

Reference publications for more weather information?

A

NP100 (Mariners Handbook)
Admiralty list of radio signals vol.3
Admiralty routeing charts
Admiralty Sailing directions
Ocean passages of the world

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12
Q

Tropical revolving storm? “Hurricane” “Typhoon” “Cyclone”

A

Non-frontal low pressure system
Intense rotating depression

Require right position and right time of the year

Require warm water (sea surface temp of at least 26-28°C)

Requires low wind shear

Requires Coriolis effect

Tend to form towards the eastern part of an ocean between 5° & 15° latitude North or South.

They move in a east-westerly fashion due to the trade winds

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13
Q

Signs of an approaching TRS? (5)

A

Barometer drops 3 millibars below the mean reading

significant change of direction or strength of wind

Long low swell is observed from the approximate centre of the storm

Heavy rain.

Lack of wildlife

General atmosphere is very oppressive and dark

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14
Q

Where do I get synoptic charts?

A

Metoffice

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15
Q

Geostrophic windspeed?

A

Wind 600m over sea level
over sea level 2/3
over land 1/3

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16
Q

Frontolysis?

A

Weakening of a front
. on a synoptic chart

17
Q

Frontogenesis?

A

Formation of a front
x on a synoptic chart

18
Q

Hydrometer?

A

Measures density

Measure density before departure to calculate stability for the voyage

19
Q

Frontal fog?

A

Warm moist air behind the warm front replacing the cooler air ahead of it
Reaches dewpoint

20
Q

Where can you find informations where and when TRSs are likely to occur?

A

NP100

21
Q

In front of a warm front? (Stage 1 of 3)

A

Clouds:
High level cirrus -> Alto stratus -> Nimbostratus

Rain:
Light showers towards the end

Visibility:
Moderate - Poor (Frontal fog)

Wind:
Backing
Will start to increase

Pressure:
Slowly dropping and a sharp drop when we enter the warm front

Temp:
Slowly increasing and a sharp increase when we enter the warm front

22
Q

Warm sector? (Stage 2 of 3)

A

Clouds:
Low clouds

Rain:
Light showers

Visibility:
Moderate - Poor (Advection fog)

Wind:
Steady

Pressure:
Low but steady

Temp:
Warm but steady

23
Q

Passage of a cold front?
(Stage 3 of 3)

A

Clouds:
Cumulonimbus

Rain:
Heavy rain and potential thunder

Visibility:
Poor in the rain, exceptional once we get out

Wind:
Veer and drop off

Pressure:
Rise

Temp:
Decrease

24
Q

What is an occluded front?

A

Warm and cold front together
Lots of clouds
Lots of rain
Poor visibility
Confused wind
Shit weather

25
Q

Trough?

A

Line of unstable air
Rain & clouds