An instrument which measures the scattering function of particles suspended in a medium in order to determine the visual range through the medium. See visibility meter.

Literally "not wet", containing no liquid.

A line of equal or constant pressure.

Automated Local Evaluation in Real Time. Network of automatic rain gauges that transmit via VHF radio link when precipitation occurs. Some sites are also equipped with other sensors such as temperature, wind, pressure, river stage or tide level. More info ...

An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.

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 ...

February 2nd. In American folklore, a day that is popularly supposed to provide the key to the weather for the remainder of the winter. Specifically, if the ground-hog upon emerging from its hole casts a shadow, it will return underground, thereby forebod ...

Solar radiation of selected wavelengths.

A graphical representation of a frequency distribution. The range of the variable is divided into class intervals for which the frequency of occurrence is represented by a rectangular column. The height of the column is proportional to the frequency of ob ...

That temperature at which, in a specified latitude, the reading of a particular barometer requires no temperature or latitude correction.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

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

Radiation with wavelengths less than 4 microns.

A mercury barometer arranged so that the position of the upper or lower meniscus may be measured photographically. In one design the image of the meniscus is formed on a rotating drum covered with sensitized paper so that a continuous record of pressure a ...

The play or loose motion in an instrument due to the clearance existing between mechanically contacting parts.

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

Erasable Programmable Read Only Memory. Programable read-only memory which can be erased, usually by ultraviolet light, and re-programmed.

A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

A forecast of the expected stage or discharge at a specified time, or of the total volume of flow within a specified Interval of time, at one or more points along a stream.

The closeness of agreement among measurements of the same value of the same quantity where the individual measurements are made under different defined conditions, i.e. by different methods or with different measuring instruments.