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. ...

The correctable part of the inaccuracy of an instrument.

The process by which small particles suspended in a medium of a different refractive index diffuse a portion of the incident radiation in all directions. In scattering no energy transformation results, only a change in the spatial distribution of the radi ...

The lowest value of a measured quality at which a sensor meets its accuracy specification.

Abbreviation for visual flight rules, but commonly used to refer to the relatively favorable weather and/or flight conditions to which these rules apply.

The height at which the maximum wind speed occurs, determined in a winds-aloft observation.

The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.

National Weather Service. Administered by the U.S. Department of Commerce.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

The distance or length of flow of the air past a point during a given interval of time.

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

A hydrometeor consisting of an aggregate of microscopic and more-or-less hygroscopic water droplets suspended in the atmosphere. It reduces visibility to a lesser extent than fog. The relative humidity of mist is often less than 95 percent.

A scale with the ice point at zero degrees and the boiling point of water at 80 degrees, with pressure of one atmosphere.

The decrease of an atmospheric variable with height, the variable being temperature, unless otherwise specified.

A set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.

The element directly responsive to the value of the measured variable.

An instrument designed to measure the effect of sunlight on evaporation from plant foliage. It consists of a porous clay atmometer whose surface has been blackened so that it absorbs radiant energy.

That portion of the atmosphere which is above the lower troposphere. Generally applied to levels above 850 mb.

A forecast of weather elements of particular interest to aviation; including ceiling, visibility, upper winds, icing, turbulence, precipitation types, and storms.

The record or trace made by a microbarograph.