A wind blowing in a direction opposite to the heading of a moving object, thus opposing the object's intended progress; the opposite of a tailwind.

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

An instrument which measures the spectral distribution of the intensity of direct solar radiation.

A type of cyanometer. an instrument used to measure the blueness of the sky. The Linke-scale is simply a set of eight cards of different standardized shades of blue. They are evenly numbered 2 to 26. The odd numbers are used by the observer if he or she j ...

An effect noted primarily in wet snow conditions when snow clings to the sides of a precipitation gauge and gradually accumulates until the gauge orifice is capped with accumulated snow. This effect can be minimized by using large collectors, and wind scr ...

A general term for instruments designed to measure the amount of cloudiness.

A type of directional antenna used on some types of radar and radio equipment consisting of an array of elemental, single- wire dipole antennas and reflectors.

Either of two colored luminous spots that appear at points 22

Determined by weighing a special type of wooden stick that has been exposed in the woods, its weight being proportional to its contained water.

A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.

To free something from the binding action of ice by warming it to a temperature above the melting point of ice. Also, a warm spell when ice and snow melt.

Integrated Flood Observing and Warning System. National Weather Service flood warning program.

An increase in the central pressure of a pressure system; opposite of a deepening. More commonly applied to a low rather than a high.

A small balloon whose ascent is followed by a theodolite in order to obtain data for the computation of winds aloft.

The total of all deviations of a transducer's output from a specified straight line in a constant environment.

A combination cup anemometer and pressure-plate anemometer, consisting of an array of cups about a vertical axis of rotation, the free rotation of which is restricted by a suitable spring arrangement.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

An instrument which automatically records the voltage applied to it, as a function of time.

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

A photometric unit of illuminance or illumination equal to one lumen per square meter