A unit of pressure which directly expresses the force exerted by the atmosphere. Equal to 1000 dynes/cm2 or 100 pascals.

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

Wind with a speed between 7 and 10 knots (8 and 12 mph), Beaufort scale number 3.

For a given locality and month, an empirical expression devised for the purpose of classifying climates numerically on the basis of precipitation and evaporation.

Thermometer used for measuring the lowest temperature attained during a given interval of time, for example, a day.

A pyrheliometer of the thermoelectric type. Radiation is allowed to fall on two concentric silver rings, the outer covered with magnesium oxide and the inner covered with lamp black. A system of thermocouples (thermopile) is used to measure the temperatur ...

See mote.

A system of physical units based upon the use of the meter, the metric ton (106 grams), and the second as elementary quantities of length, mass, and time, respectively.

Precipitation of very small, white opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm. The solid equivalent of drizzle.

A line of equal or constant pressure.

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

A thermometer whose sensitive element has been made to resemble a black body by covering it with lamp black. The thermometer is placed in an evacuated transparent chamber which is maintained at a constant temperature. The instrument responds to insolation ...

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

NEXt Generation RADar. A NWS network of about 140 Doppler radars operating nationwide.

The length of air flow past a wind vane required for the vane to respond to 50 percent of a step change in wind direction. Expressed in feet or meters and calculated from delay time times wind tunnel speed.

A small balloon, loaded with ballast and inflated so that it will explode at a predetermined altitude, which is attached to a larger balloon.

An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

A number of quantity defining a limit that errors will not exceed when a device is used under specified operating conditions. Accuracy rating can be expressed in a number of forms, i.e. in terms of the measured variable (+/- 1 C), percent of span (+/-0.5% ...

The elevation of the water surface in a stream as measured by a river gauge with reference to some arbitrarily selected zero datum.

A precipitation gauge consisting of a receiver in the shape of a funnel which empties into a bucket mounted upon a weighing mechanism. The weight of the catch is recorded as inches of precipitation.