| term | meaning (click term for explanation in text) |
| acceleration zone | area subject to increased wind because of the way the air flows round high land |
| advection | see fog, advection |
| air mass | term used to describe a large region of atmoshperic air with similar properties, e.g. wet, dry, warm, cold |
| anticyclone | an area of high pressure |
| Atlantic depression, Atlantic low | a frontal low pressure system that forms in the north Atlantic - the cause of much wind and rain in the UK and Ireland |
| backing | wind changing direction in an anticlockwise sense e.g. west to south |
| bar | unit of pressure approximately equal to the average atmospheric pressure: 1000 milibars |
| Beaufort scale | standard scale for wind strength |
| Buys Ballot's Law | law of meteorology which describes the relationship between wind and atmoshperic pressure |
| cold front | a front in which a cold air mass is "pushing into" a warm one, giving particular weather characteristics |
| convection | vertical movement of air due to temperature: warm air rising |
| coriolis | effect which causes objects/fluids to move in a curved line on the earth, due to its rotation |
| cumulonimbus Cb | type of cloud: towering cumulus with rain or hail showers |
| cumulus Cu | type of cloud: isolated, low level fluffy clouds, caused by convection |
| cyclonic | wind changing direction due to close passage of the centre of a depression |
| depression | see Atlantic depression |
| fetch | distance the wind blows over sea to build up waves |
| fog | term for visibility of less than 1000m |
| fog, advection | fog which forms when "wet" air blows over a cold surface |
| fog, radiation | fog which forms when land cools down at night under clear sky |
| front | weather pattern caused by two air masses meeting - usually part of a low pressure system |
| good (visibility) | visibility greater than 5 miles |
| gradient wind | general (as opposed to local) wind caused by the atmospheric pressure distribution |
| hectopascal | unit of pressure equal to milibar |
| high (pressure) | see anticyclone |
| high, very high (sea state) | sea states with greater than 6m wave height |
| imminent | within 6 hours of the issue time of the forecast/warning |
| inshore waters forecast | forecast service from UK Met Office, for up to 12 miles offshore |
| isobar | line on a weather map joining places of equal atmospheric pressure |
| katabatic wind | wind caused by cold air flowing down from high ground |
| land breeze | local off-shore wind near coast at night, caused by air cooling and sinking over land |
| later | more than 12 hours from the issue time of the forecast | low | see Atlantic depression |
| Marinecall | UK weather forecasting service |
| milibar | unit of atmospheric pressure, approx one thousandth of average atmospheric pressure |
| moderate (sea state) | sea state with wave height between 1.25m and 2.5m |
| moderate (visibility) | visibility between 2 and 5 miles |
| occlusion, occluded front | type of front where the warm air mass is no longer in contact with the surface |
| phenominal (sea state) | something you probably never want to experience: wave height in excess of 14m |
| poor (visibility) | visibility between 2 miles and 1000m |
| pressure gradient | area of changing atmospheric pressure (analogous to sloping ground) |
| ridge | elongated area of high pressure |
| rough, very rough | sea states: wave height 2.5m to 4m; and 4m to 6m |
| sea breeze | local wind near the coast, caused by warm air rising over the land |
| sea state | description of how rough the sea is: wave height in open water |
| secondary depression | a depression that forms along a front from another depression |
| slight | sea state with wave height from 0.5m to 1.25m |
| smooth | sea stath with wave height less than 0.5m |
| soon | between 6 and 12 hours from time of issue of forecast/warning |
| synoptic chart | weather chart showing isobars and fronts |
| unstable atmosphere | condition when upper air is particularly cold, favouring the development of cumulonimbus clouds and heavy showers |
| veering | wind changing direction in a clockwise sense e.g. west to north |
| vortex | circular movement of fluid round extreme low pressure (e.g. plug hole in bath!) |
| warm front | a front in which a warm air mass is "pushing into" a cold one, giving particular weather characteristics |
| water vapour | invisible gas state of water, generally part of the mix of gasses in atmosperic air |