What is the Jetstream and how does it affect us?
- High altitude fast moving band of air
- Boundary zone between polar and temperate air
- Allows for the formation of lows
- Lows move along jetstream
- Jetstream is 6mile high, 100km wide and 3 km deep.
- Moves with earth & temperature of sun
What is Advection fog. How is it formed?
- Warm moist air over cold sea.
- May form and persist even with strong winds.
- Common during spring and early summer
- Needs some turbulence to spread i.e. light winds.
What is the Met Office’s involvement with weather forecasting for seafarers?
- Issues forecast 4 x per day
- Gale forecasts, inshore waters, strong winds, high seas and storm warnings
- Can be distributed by VHF / MF/ HF, SAT-C, NAVTEX, fax, email, radio / tv
What are the features of an occluded front?
- Cold front has caught up with warm front
- Warm air mass now trapped
- High winds close to centre
- Large amounts of precipitation
What is Sea smoke and how is it formed?
- Cold dry air moves over warm sea surface
- Evaporates from surface of water
- Air is unable to contain water vapour so immediately condenses.
How can the weather be observed on board?
- Barometer
- Thermometer (wet and dry bulb)
- Radar -> Rain / precipitation
- Wind speed and direction
- Cloud recognition
What is the Jetstream?
- High altitude fast moving band of air
- Boundary zone between polar and temperate air
- Allows for the formation of lows
- Lows move along jetstream
- Jetstream is 6mile high, 100km wide and 3 km deep.
- Moves with earth & temperature of sun
What is Radiation fog and how is it formed?
- Low land and clear nights
- Long wave radiation
- Cools below dewpoint
- Sea temperature is warmer than land.
- Easily dispersed.
Where can expected weather conditions be found?
- Routing charts
- Admiralty sailing directions
- Ocean Passages for the world
- Weather routing services
- Mariners’ handbook.
How does the Jetstream affect the UK?
- Drives low pressure towards UK.