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The terms and definitions found in the glossary relate to the science of meteorology.
For descriptions and definitions of words used in the Bureau's forecasts and warnings, please refer to Weather Words.
- Gale Warning
- A Gale Warning is a statement which warns of winds averaging from 34 knots and up to 47 knots in coastal waters and high seas areas.
- Geopotential height
- Geopotential height approximates the actual (gravity-weighted) height of a pressure level above mean sea-level.
- Geostrophic wind
- When the wind is steady, horizontal, and flowing parallel to straight isobars it is called the geostophic wind. Where the Pressure Gradient force is exactly balanced by the Coriolis force.
- Gradient wind
- A steady, horizontal wind flowing along curved isobars is called gradient wind. Where there is imbalance between the pressure gradient and Coriolis forces.
When the pressure gradient force is greater than the Coriolis force, the flow takes on a curved path around low pressure.
When Coriolis is the larger force, the curved flow is around high pressure. - Greenhouse effect
- A natural warming process of the earth. When the sun's energy reaches the earth some of it is reflected back to space and the rest is absorbed. The absorbed energy warms the earth's surface which then emits heat energy back toward space as longwave radiation. This outgoing longwave radiation is partially trapped by greenhouse gases such as carbon dioxide, methane and water vapor which then radiate the energy in all directions, warming the earth's surface and atmosphere.
Without these greenhouse gases the earth's average surface temperature would be about 33 degrees Celsius cooler.
Click here for more information. - Global radiation
- Global (short wave) radiation includes both that radiation energy reaching the ground directly from the sun, and that received indirectly from the sky, scattered downwards by clouds, dust particles etc.
- Gust
- A gust is any sudden increase of wind of short duration, usually a few seconds.