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 273.16 K. The size of the degree is the same as on the Celsius scale, and the zero point is absolute zero.

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.

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 atmosphere, or 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.