A type of pressure-tube anemometer, named after the inventor.

An instrument for measuring radiant energy. It consists of an ether differential thermometer with blackened bulbs. One of the bulbs is exposed to the unknown radiation and the other to a black body source whose temperature can be varied. Equality of radia ...

Radiation coming from the solid angle of the sun's disc, as opposed to diffuse sky radiation, effective terrestrial radiation, or radiation from any other source. Direct solar radiation is measured by pyrheliometers.

Rate of flow of water past a point in a stream, expressed as volume per unit time, i.e. cubic feet per second.

Apparatus designed to measure and record the size distribution of raindrops as they occur in the atmosphere.

An instrument for measuring snow hardness in terms of the resistance of snow to the pressure exerted by a disk attached to a spring-loaded rod, a gauge calibrated in pounds per square inch registers the amount of resistance. See Canadian hardness gauge.

The length of fluid flow (gas or liquid) past a sensor required for the sensor to respond to 63.2% of a step change in speed. Expressed in feet or meters. For anemometers, this value is calculated from time constant times wind tunnel speed.

A photoelectric spectrophotometer which is used in the determination of the ozone content of the atmosphere.

An instrument for measuring the ultraviolet in solar and sky radiation.

A technique for making winds aloft observations in which two theodolites located at either end of a baseline follow the ascent of a pilot balloon. Synchronous measurements of the elevation and azimuth angles of the balloon. taken at periodic intervals, pe ...

A relatively small-scale, downward moving current of air.

Solar and terrestrial radiation directed downwards (towards the earth's surface); incoming radiation.

The direction toward which the wind is blowing; with the wind.

The size of the area comprising a watershed or river basin. Also called catchment area.

Very small precipitation drops (diameters less than 0.5 mm) that appear to float with air currents while falling in an irregular path. Unlike fog droplets, drizzle falls to the ground.

A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.

An instrument used to measure the amount of dew formed on a given surface.

The rate of decrease of temperature with height when unsaturated air is lifted adiabatically (without exchange of heat with its surroundings). The decrease is due to expansion as the air is lifted to a lower pressure.

Technically, the temperature registered by the dry-bulb thermometer of a psychrometer. However, it is identical with the temperature of the air and may also be used in that sense.

Companion to the wet-bulb thermometer in a psychrometer. Used to measure ambient air temperature.