Sea weather
Sea weather includes all weather phenomena at sea (on the sea and the coasts) and is a sub-area of meteorology .
Historical meaning
The wind was the driving force for the sailing ships of merchant shipping until the 18th century. Wind direction and wind strength were the most important information for estimating the necessary travel time and possible dangers. From the experience gained over centuries, the most important seasonal global wind currents and ocean currents were shown in wind maps.
research
In addition to meteorology, hydrology , oceanography and climatology also deal with sea weather . The energy exchange via wind, waves, currents, evaporation and precipitation, driven by temperature and pressure differences as a result of solar radiation, is examined. These and many other forces that determine the weather are in a highly complex systemic relationship. The aim of marine weather research is to reliably forecast wind, waves, currents and other values that are important for seafaring.
wind
Wind direction and wind strength are decisive for locomotion while sailing and for assessing possible dangers at sea. From long-term observations, seasonal values are shown in the so-called "monthly maps" ("pilot charts") with wind arrows and wind diagrams. For current forecasts, air pressure and temperature are recorded worldwide and processed in complex computer models in large computers.
wave
The wave height ( swell ) is directly dependent on the strength of the wind, and also on its duration and length of attack. The wave is sluggish: when the wind has subsided, it remains as a swell for hours or even days. If a swell that has built up over a long period of time comes together with waves from a current wind ( wind sea ), dangerous cross lakes are created . These also occur when waves or swells meet a strong current.
flow
The warming and cooling and the different salinity of water masses and the resulting transport of energy is a motor of global weather. The main currents are the Gulf Stream , Labrador Current , Equatorial Current , and North Atlantic Deep Water . Currents are important to shipping because they increase or decrease cruising speed or move ships sideways.
Global wind systems
This describes the global shift of air masses between the climatic zones ( tropics , low pressure channels , subtropics ), caused by temperature differences and the resulting high pressure areas and low pressure areas and the wind that creates the pressure compensation, e.g. trade winds , monsoons . Or the formation of cyclones and typhoons , and what happens in weather fronts .
Local wind systems
Here local weather phenomena are described, for example the land wind and the sea wind , caused by different degrees of warming of land and water by solar radiation. Or seasonal wind systems such as Bora , Meltemi , Scirocco and Mistral , or the formation of thunderstorms .
Sea weather reports
Independent sea meteorological services or specialist departments of weather services create weather forecasts for both coastal shipping. These can be sea weather reports or maps. Maps for the forecast swell or wind sea are also offered according to requirements. For the oceans with their longer passages, forecasts of the high altitude weather are also made available, which enable your own assessment of the long-term development.
North and east Sea
The maritime weather service of the German Meteorological Service publishes a maritime weather report as well as maritime weather maps for the North and Baltic Seas. The coast station DP07 offers a daily weather report for the North and Baltic Seas. The BBC's marine weather report for the North Sea, the Shipping Forecast, is also well known .
Worldwide
OpenSeaMap offers a meteogram for 5000 ports worldwide with an 8-day forecast for wind direction, wind strength, air pressure, air temperature, relative humidity, cloud cover and wave height. A worldwide wind map is displayed on the nautical chart , with wind forecasts for 3 days. Wind direction and wind strength are shown as wind arrows.