Glossary of Meteorological Terms (K)

K

Katabatic wind

Any wind blowing down an incline. If warm, it is a foehn. If cold, it may be a fall wind or a gravity wind.

Katathermometer

A type of cooling-power anemometer based upon the principle that the time constant of a thermometer is a function of its ventilation.

Kelvin temperature scale

An absolute temperature scale with the ice point of pure water defined as 273.16K. The size of the degree is the same as on the Celsius scale, and the zero point is absolute zero. Temperatures on this scale are called kelvins, not degrees kelvin, the unit kelvin is not capitalized, and the symbol (capital K) stands alone with no degree symbol. There are no negative temperatures in the Kelvin scale. In photometry, the Kelvin scale is used to express "color temperature," a simplified way to characterize the spectral properties of a light source. Technically, color temperature refers to the temperature to which one would have to heat a theoretical "black body" source to produce light of the same visual color. The Kelvin temperature scale is named after the British mathematician and physicist William Thomson (Lord Kelvin), who proposed it in 1848.

Kew-pattern barometer

Mercurial barometer with a fixed scale and cistern and which therefore requires only one adjustment before each reading.

Kilogram calorie

See calorie.

Koschmieder’s law

A basic equation in daytime visual range theory, relating the apparent luminance of a distant black object, the apparent luminance of the background sky above the horizon, and the extinction coefficient of the atmosphere.

Knot

The unit of speed in the nautical system; one nautical mile per hour. It is equal to 1.1508 statute miles per hour or 0.5144 meters per second.

Konimeter

An instrument for determining the dust content of a sample of air. Also spelled conimeter.

Koniscope

An instrument which indicates the presence of dust particles in the atmosphere. Also spelled coniscope.

Koschmieder’s Law

A basic equation in daytime visual range theory, relating the apparent luminance of a distant black object, the apparent luminance of the background sky above the horizon, and the extinction coefficient of the air layer near the ground. Also called airlight formula.

Krypton

An inert gas. An element found in the atmosphere to the extent of only 0.000114 percent by volume. Its molecular weight is 83.7.

Kytoon

A captive balloon used to maintain meteorological equipment aloft at approximately a constant height. The kytoon is streamlined and combines the aerodynamic properties of a balloon and a kite.