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Weather Glossary - K


Katabatic wind

A local wind which develops due to cool, dense air flowing downhill. The cooler air is generally a result of night time radiational cooling in the lower layers of the atmosphere, but katabatic winds also occur over snow fields and glaciers. See also anabatic winds.


A front where the warm air descends the frontal surface, except in the low layers.


Unit of thermodynamic temperature. Zero Kelvin is absolute zero (-273.15░C). Temperatures in Kelvin can be obtained from temperatures in Celsius by the formulae K=C+273.2.

Kelvin-Helmholtz billows

A phenomenon that occurs in a high-shear environment between two layers of fluid which are stably stratified (i.e. a denser fluid beneath a lighter fluid).

Kinetic energy

The energy a body possesses as a consequence of its motion. Defined as half the product of its mass and the square of its speed.


The unit of speed equal to 1 nautical mile/hour, or 1.85 km/h. The knot is commonly used to report wind speed and ocean current speed.


[Slang] Lumpy protrusions on the edges, and sometimes the underside, of a thunderstorm anvil. They usually appear on the upwind side of a back-sheared anvil, and indicate rapid expansion of the anvil due to the presence of a very strong updraft. They are not mammatus clouds. See also cumuliform anvil, anvil rollover.

K°ppen's classification of climates

Classification of climate based on annual and monthly means of temperature and precipitation which also takes into account the vegetation limits. It is a tool for presenting the world pattern of climate and for identifying important deviations from this pattern.

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Weather News

Aurora Australis puts on a show

11:14 EDT

The last few nights have brought a spectacular light show to Tasmania, southern Victoria and New Zealand, with the potential for more to come over the next few weeks.

Grantham floods inquiry: Denis Wagner considers legal options after report finds quarry impact 'insignificant'

07:47 EDT

The former owner of the Grantham quarry is considering his legal options after an inquiry found it did not contribute to the town's deadly 2011 floods.

Grantham floods inquiry: Quarry played 'insignificant' role in disaster, commission rules

19:22 EDT

The Grantham Floods Commission of Inquiry has ruled the Grantham quarry played little role in the deadly 2011 flood and its owners were unjustly blamed.