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Weather glossary: What does it all mean?

Published: 3:17PM Monday December 10, 2007

Common weather terms

Fine: Dry weather with mainly sunny or bright conditions - characterised by an absence of precipitation.

Dry: Free from rain.

Precipitation: Any type of water particle (e.g.rain, hail or snow), that falls to the ground.

Rain: Precipitation from dense, continuous clouds.

Shower: Precipitation from individual clouds. Relatively short-lived and punctuated by periods of blue sky.

Drizzle: Precipitation made up of small water droplets that are close to one another.

Snow: Frozen precipitation in the form of ice.

Fog: Very small water droplets suspended in the air, which reduces visibility at ground level to less than a kilometre.

Mist: Like fog, but visibility is more than a kilometre.

Cloudy: More cloud than clear sky. e.g the sun being obscured by cloud for long periods of time.

Sky covered by cloud.

Low pressure system*: A low pressure system is usually formed by a mass of warm air being forced upwards by cold air. Air pressure decreases toward the centre and often results in unsettled weather conditions.

High pressure system*: Also known as anti-cyclones high pressure systems are areas of high atmospheric pressure which have diverging winds. They generally create cooler, dryer temperatures, with little or no clouds.

Isobar: A line of equal or constant atmospheric pressure (see high and low pressure systems). Usually the closer isobars are together the stronger the winds are.

Front: The point at which two different air masses meet, sometimes resulting in severe weather changes. A cold front is where colder air overtakes and replaces warm air and a warm front is therefore where warm air overtakes and replaces colder air.

*Low and high pressure systems are measured by hectopascals (hPA).

Distribution of weather phenomena

Isolated: Showers/rain are separated in space during a certain time period.

Scattered: Showers/rain can occur anywhere in a particular area. Slightly more frequent that isolated conditions.

Patchy: Occurs irregularly over a particular area.

Occurs extensively throughout an area.

Squally: Brief periods of violent wind or rain.

What is wind and types of wind
Wind is air that flows from an area of high pressure to an area of low pressure. It is measured by speed, and direction. Winds are named by the direction they blow from i.e southerly winds blow from the south.

Gust: Any sudden increase of wind of short duration (usually just a few seconds).

Gale: A very strong wind of at least 28 knots (51 kph) and up to 55 knots (102 kph).