A direct-vision nephoscope constructed in the following manner: A grid-work of bars is mounted horizontally on the end of a vertical column and made free to rotate about the vertical axis. The observer rotates the grid and adjusts his or her position unti ...

General term for an instrument which records the vertical electric current in the atmosphere.

An instrument for measuring radiant energy. See actinometer, Dines radiometer, photometer, Tulipian radiometer.

Precipitation composed of balls or irregular lumps of ice with diameters between 5 and 50 mm.

A liquid-in-glass or liquid-in-metal thermometer using mercury as the liquid.

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

An inert gas. A colorless, monatomic element which is found to occur in dry air to the extent of only 0.000524 percent by volume. Helium is very light, having a molecular weight of only 4.003 and specific gravity referred to air of 0.138. Because helium i ...

A self-recording thermometer.

The general term for dry atmospheric suspensoids, including dust, haze, smoke. and sand. Compare to hydrometeor.

Instrument for measuring the intensity of radiant energy. Its principle is based on the variation of electrical resistance, with the incoming radiation, of one or both the metallic strips which the instrument comprises.

Instrument for measuring the depth to which the soil is frozen.

Of or pertaining to rain.

An inert gas. An element found in the atmosphere to the extent of only 0.000114 percent by volume. Its molecular weight is 83.7.

The height of the cloud base above the local terrain.

The volume of water required to cover one acre to a depth of one foot: 43,560 cubic feet.

An instrument consisting of a series of graduated cylinders possessing selective collection efficiencies. It is used for the measurement of quantities relating to the size distribution of cloud droplets.

A buoyant balloon kept from rising freely by means of a line secured to a point on the ground, as opposed to a free balloon. See kytoon.

A device which converts energy from one form into another, i.e. an ac generator transducer which converts the mechanical motion of anemometer cups into an electrical signal.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.