MET Flashcards
What are the signs of an approaching TRS
Long swell from direction of TRS
Extensive high cirrus cloud from direction of TRS
Drop in 3Hpa or more below mean pressure
A noticiable change in wind speed and direction
What are the six degrees of freedom
Pitch Roll Yaw heave sway surge
How would you care for your barometer?
keep out of direct sunlight. Keep away from air flow/ air con etc. dust free. Securely fastened at eye level on a secure bulkhead away from vibration.
What is Radiation Fog?
Radiation Fog is generally only found around coastal areas. It is formed on land and moves to the sea. Generally formed in anti cyclonic weather systems with clear sky and no or light winds. The land cools the air to due point temp as it cools during the night. Becomes thicker throughout the night, then gravity pushes it down onto the sea. Dissipates during the day when heated by the sea.
What is Advection Fog?
Advection Fog Forms on the water when warm air moves over a cool sea, causing the water in the air to turn to water vapour.
Define the rotation of HP and LP systems in each hemisphere and the buys ballot law
S.H - LP = clockwise (face wind, left hand out to center)
Describe the effect of barometric pressure on tides and define a storm surge
Higher pressure = lower water level. Every 10Hpa of barometric pressure above/below 1013 will result in 0.1m change in water level. Thus 1HpA = 1cm.
Storm surge = Rise in water level due to lower atmospheric pressure and the effect of wind pushing the water on the land
What is relative humidity
The ratio between the amount of water currently in the air and the maximum amount of water the air can hold.
What conditions are required to form a TRS (tropical cyclone)
Ocean temp of 26.5 at least 50m
Atmospheric instability
High humidity
At least 4.5 deg lat (to allow coriolis force to work)
Low vertical wind shear
Where would you find your weather information for an upcoming passage
1) Official meteorological information provider for that area, e.g) MetService
2) weather routing systems and charts.
3) Internet, predict wind etc.
4) Email routing
5) VHF, inmarsat, Navtex.
What Relative Humidity is necessary for Fog to form
100%
What would we want to consider with regards to weather before departing?
Forecasts from Official sources.
Where to - from
When - Depart arrive
Routing weather charts and ocean passages of the world (NP136)
Sailing directions for arrival port
Insurance
ISM limitations
ICLL seasonal zones
Nav area - met provider (INMARSAT / NAVTEX / HF)
Ship weather routing services
What info would we get on weather routing charts
Climate data
% of time wind blows in certain directions/strengths
Ice Lines
TRS seasonal zones
