Meteorology Flashcards
Name some sources of meteorological information?
- UK offshore shipping forecast through NAVTEX, BBC radio 4 and MF/VHF
- From the 21 METAREAS
- Relevant internet sources like the Met Office
- Can refer to ALRS volume 3 for broadcast details
- Routeing charts
What weather would you expect with a high pressure reading on the barometer?
You would expect to see calm, clear, sunny conditions but possible trapped cloud or fog.
What weather would you expect with a low pressure reading on the barometer?
You would expect to see clouds and precipitation with areas of deep lows potentially leading to storm conditions.
What is a barometer?
A barometer is an instrument that gives an indication of the atmospheric pressure at the time of checking.
What is a hygrometer?
The purpose of the hygrometer is to measure the amount of humidity in the air.
You would measure the difference between the ‘wet’ and ‘dry’ bulbs, which is called the ‘depression of the wet bulb’
Using this information you are able to look up the dew point from the dew point table in the mariners handbook (NP100), which will indicate the likelihood of fog occurring.
What is the anemometer?
An anemometer indicates the wind speed and direction.
It can be used to assist the bridge team in ensuring that the ship remains on its charted track.
How do you know the wind direction from a synoptic chart?
Air moves around high pressure in a clockwise direction
Air moves around low pressure in a anti-clockwise direction
What do the isobars indicate on a synoptic chart?
They indicate the strength of the wind.
If they are close together there will be a strong wind and if they are further apart they less strong.
What is a warm front?
A warm front is shown as a red semi-circle line on a synoptic chart.
Warm air will follow the front and along the front an increase in the amount of cloud and rain will be likely.
What is a cold front?
A cold front is shown as blue triangles line on a synoptic chart.
Cold air will follow the front and along the front a increase in the amount of cloud and rain will be likely.
What is a warm sector?
A warm front is located between two fronts, the weather you can expect in the sector is usually fairly cloudy, mist, fog and out breaks of rain.
What is an occluded front?
A occluded front is shown as purple triangles and semi-circles line on a synoptic chart.
This front is when a cold front catches up to a warm front, within this sector low cloud and patchy rain will be experienced.
What is a trough?
A trough is shown as a black line with no shapes on a synoptic chart.
They mark areas of unstable air and showers would be expected.
What is a geostrophic wind scale on a synoptic chart?
It is the geomagnetic activity index, used to describe the earths disturbance of the magnetic field caused by solar wind.
What is a Tropic Revolving Storm?
A TRS is named different depending on their location in the world:
- Atlantic = Hurricanes
- Pacific = Typhoons
- Indian Ocean = Cyclones
TRS’s usually form between 5’N - 20’N and 5’S - 20’S and they usually track west until they curve towards each poles. In the northern hemisphere they rotate anti-clockwise and in the southern hemisphere they rotate in a clockwise direction.
