Skysail Training © K M Bater 2012 1 of 20 © SKYSAILTRAINING 2012 Feedback is welcome Click on for...

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Skysail

Training

© K M Bater 2012© SKYSAILTRAINING 2012

Feedback is welcome

Click on www.skysailtraining.co.uk

for on line Colregs test and CEVNI test and to buy Weather, Colregs, VHF and more

navigation skills charts

Test Yourself - Online ExamRYA Day Skipper and Yachtmaster

ICC / BSAC SeamanshipMet - Weather Exam / Assessment

MeteorologyWeather at Sea

Mouse click or Page Down to start

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© K M Bater 2012

SKYSAIL SKILLS CHARTS

http://www.btinternet.com/~keith.bater/navigation_skills_charts.htm

Day Skipper

ChartworkWeather

VHF

Extracts from Skysail Skills Charts on the essential navigation subjects – all summarised on A4 laminated charts. For full details click link above

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Before the Meteorology tests

• Here is the full weather presentation if you need it (2MB):

http://www.btinternet.com/~keith.bater/weather_for_yachtmaster_day_skipper_course.pdf

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Forecasts

Where would you find weather forecasts?

On land At seaTVNational radioLocal radioNewspapersTeletextWebBarometerMobile phone

BBC radioCoastguard VHF Metfax to PCNavtexBarometerObservationMobile phone

Day Skipper Weather

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Forecasts

What is the sequence of the Shipping Forecast?

Gale warnings

Day Skipper Weather

General Synopsis at time of issueWind now - direction and forceWind laterSea stateWeather - fair, rain, etcVisibility

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Shipping Forecast Terms

What do the following mean?Within 6 hoursImminent

SoonLater

6 to 12 hours

After 12 hours

of the time of issue of the forecast

Very poor

Poor

Moderate

Good

< 1000 metres visibility

< 2 Miles

> 5 Miles

2 - 5 Miles

Fair No precipitation

1.25 – 2.5

2.5 – 4.0

4.0 – 6.0

Moderate

Rough

Very rough

Wave height m

Day Skipper Weather

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Wave height

What factors affect wave height?

Wind speed and duration

Tide speed and direction wind against tide gives higher waves

Depth of water

Fetch - the distance over which the wind blows

Swell - the wave pattern before the current weather

1

2

3

4

5

Day Skipper Weather

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Wind

How do you define the following?

Direction

Cyclonic

Veering

Backing

Direction from which wind blows

Changing direction clockwise

Rapid changes in wind direction(Possibly at the centre of a depression)

Changing direction anticlockwise

Day Skipper Weather

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Training

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Pressure / Wind / Waves

What is likely if the pressure has changed by 6 millibars in the last 3 hours?

A gale(whether the change is rising or falling)

Day Skipper Weather

From these descriptions estimate what the Beaufort wind force is:

a) Moderate waves, many white crests.

b) Sea heaps up, spray, breaking waves, foam blows in streaks.

Force 5 17-21 knots

Force 7 28-33 knots

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Training

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Fronts / Buys Ballot

How do you define the following?

Occluded Front

Buys Ballot’s Law in the Northern Hemisphere, if you stand with your back to the wind, the area of low pressure is to your left and the high pressure to the right.

An occluded front is formed when the faster moving cold front overtakes and merges with the warm front. Typical weather is cloudy, with light rain and poor visibility

Warm Front

Cool air

Warm air

Advancing cold air

Cold Front

OccludedFront

Day Skipper Weather

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Training

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Depressions

What is the weather and wind at A, B, C, D?

A

BC

L

Day Skipper Weather

H

D

FairLight winds

Clear, brightShowersGood visibilityWind veers and increases

CumulonimbusHeavy rainThunder LightningSqualls

Broken cloudShowersVery poor visibilityWind steady

Light RainWind backs

Heavy rainPoor visibilityWind increases

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Training

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Coldfront

Warmfront

Warmsector

F

Depressions

What is the weather at A, B, C, D, E, F, H?

NimbostratusHeavy rainPoor visibilityWind increases

CumulonimbusHeavy rainLightning ThunderSqualls

A

E

D

B

C

Cirrus, fair

Cirrostratus

AltostratusLight RainWind backsPressure falls

Broken cloudAlto cumulusShowersVery poor visibilityWind veers, steadyPressure is steady

Yachtmaster Meteorology

H

FairLight winds

Clear, bright.Cumulus ShowersGood visibility except in showers.Wind veers sharply and increases.Pressure rises

L

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Clouds

What type of clouds and what do they signify?

Cumulus - fair weather

Cumulonimbus - thundercloud, squally, lightning. Cold front.

Cirrus - can indicate an approaching depression


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Training

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Sea Breezes

SEA AIRMoist & cool

Cumuluscloud

LAND AIRDry & warm

Cloudcurtain

Highpressure

Offshore gradient wind

Lowpressure

Sea Breeze front

Upper returncurrent

Sea breezes are caused by unequal heating of land and sea surfaces. During the day, especially in summer, solar radiation heats the land surface to become warmer than the sea surface which stays cold all summer. The temperature difference rises to a maximum around mid afternoon. The warm air rises over the land and cool air from the sea is drawn in, setting up an onshore wind. As the heating effect increases, the sea breeze strengthens, and may reach 15 knots (F4). A land breeze develops at night as the land cools relative to the sea and an opposite but weaker circulation sets up.

What is a sea breeze?What causes it?


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Sea Fog

1.What causes sea fog?

2.In which season is itmost frequent?

3.Will there be wind?

4.What makes it clear?

It occurs when warm air flows overa cold sea surface (advection flow).

Spring / early summer whenthe sea is still cold.

Yes

A change in wind directionor sea temperature


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Land Fog

1.What causes land fog?

2.In which season is it mostfrequent?

3.Will there be wind?

4.What makes it clear?

It occurs when land coolsovernight by radiation of heat. The air cools and moisture condenses to form fog.

Late Autumn / Winter when pressure is high and thereis no cloud.

No. Land fog can form in valleys and drift out to sea.

The heat of the sun thefollowing morning.


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Coastal Winds

With the gradient wind as shown, what will the wind be on the coast lines?

Gradient wind

Sea wind

Land

win

d

Land wind

Sea wind

Winds diverge.

Coastal wind is weaker

Winds converge.

Coastal wind is stronger


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Training

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Depression

Cold Front

Cold Air

WarmSector

Cool Air 20

,00

0 f

t

EastWest

Nimbostratus

Cirrostratus

Altostratus

Warm Front

Cumulus

Cumulus

Cumulonimbus

Cirrocumulus

Altocumulus

Stratocumulus

600 M300 M200 M

PASSAGE OF A DEPRESSIONCirrus

Warm AirFractostratus

WIND Strong gustsVeering sharply

SquallsSteady Veering Backing & increasing WIND

PRESSURERising, then

steadyRising quickly Steady Steady Falling PRESSURE

RAINSunny, squally

showersHeavy rain,thunder, hail

Lightrain

DrizzleBecoming heavier and

prolongedRAIN

VISIBILITYGood exceptin showers

Poor in rainPoorFog

Poor Deteriorating VISIBILITY

TEMP Cold Falls Warm Warm Rising TEMP

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Pressure Systems

What is the likely wind at A, B, C ?Variable, light

SW, light

NW, strong

SSE, strongC

LL

A

H

LB

H

DL

Deep depression


Skysail Training © K M Bater 2012 1 of 20 © SKYSAILTRAINING 2012 Feedback is welcome Click on for...

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