This weather glossary contains information on more than 2000 terms,
phrases and abbreviations used by the National Weather Service (NWS)...
the government agency who makes weather forecasts, and issues weather advisories, watches, and warnings, for the United States, and its
territories.

Many of these terms and abbreviations are used by NWS forecasters to communicate between each other and have been in use for many years and
before many NWS products were directly available to the public. It is the purpose of this glossary to aid you in better understanding NWS products.

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K
Smoke- Smoke in various concentrations can cause significant problems
for people with respiratory ailments. It becomes a more universal
hazard when visibilities are reduced to ? mile or less.

K AMS
Cold Air Mass

K Corona
In solar-terrestrial terms, of the white-light corona (that is, the
corona seen by the eye at a total solar eclipse), that portion which is
caused by sunlight scattered by electrons in the hot outer atmosphere
of the sun.

K-Index
A measure of the thunderstorm potential based on vertical temperature
lapse rate, moisture content of the lower atmosphere, and the vertical
extent of the moist layer. The temperature difference between 850 mb
and 500 mb is used to parameterize the vertical temperature lapse rate.
The 850 dew point provides information on the moisture content of the
lower atmosphere. The vertical extent of the moist layer is represented
by the difference of the 700 mb temperature and 700 mb dew point. This
is called the 700 mb temperature-dew point depression. The index is
derived arithmetically and does not require a plotted sounding.

K-index = (850 mb temperature - 500 mb temperature) + 850 mb dew
point - 700 mb dew point depression.

Katabatic Wind
A wind that is created by air flowing downhill.

Katafront
A front where the warm air descends the frontal surface (except in the
low layers of the atmosphere).

Keetch-Byrum Drought Index
An index used to gage the severity of drought in deep duff and organic
soils.

Kelvin Temperature Scale
An absolute temperature scale in which a change of 1 Kelvin equals a
change of 1 degree Celsius; 0øK is the lowest temperature on the Kelvin
scale. The freezing point of water is +273øK (Kelvin) and the boiling
point of +373øK. It is used primarily for scientific purposes. It is
also known as the Absolute Temperature Scale.

Kelvin Waves
Fluctuations in wind speed at the ocean surface at the Equator result
in eastward propagating waves, known as Kelvin Waves. Kelvin Waves
cause variations in the depth of the oceanic thermocline, the boundary
between warm waters in the upper ocean and cold waters in the deep
ocean. They play an important role in monitoring and predicting El Ni¥o episodes.

Kelvin-Helmholtz Waves
Vertical waves in the air associated with wind shear across
statically-stable regions. Can appear as breaking waves and as braided
patterns in radar images and cloud photos.

Kilopascal
The internationally recognized unit used by the Atmospheric Environment
Service for measuring atmospheric pressure. Abbreviated kPa.

Kinetic Energy
Energy that a body has as a result of its motion. Mathematically, it is
defined as one-half the product of a body's mass and the square of its
speed (KE = 1/2 * mass * velocity squared).

Klystron
An electron tube used as a low-power oscillator or a high-power amplifier
at ultrahigh frequencies.

Knot
(abbrev. Kt) Unit of speed used in navigation, equal to 1 nautical mile
(the length of 1 minute latitude) per hour or about 1.15 statue miles
per hour, or 0.5 meters/sec).

Knuckles
Slang for 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 and anvil rollover.

Kp Index
A 3-hourly planetary geomagnetic index of activity generated in
Gottingen, Germany, based on the K Index from 12 or 13 stations
distributed around the world.

KT
(Knot)- Unit of speed used in navigation, equal to 1 nautical mile (the
length of 1 minute latitude) per hour or about 1.15 statue miles per
hour, or 0.5 meters/sec).

KTS
Knots
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