A line drawn through geographical points where a given seasonal biological event occurs on the same date.

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

An instrument for determining the direction of cloud motion. There are two basic designs of nephoscope, the directvision nephoscope and the mirror nephoscope.

A navigational aid used to facilitate the landing of an aircraft at an airport in instrument weather, i.e. low visibility.

An instrument that automatically records pressure and temperature.

A mercury barometer designed for use aboard ship. The instrument is of the fixed-cistern type (see Kew barometer). The mercury tube is constructed with a wide bore for its upper portion and with a capillary bore for its lower portion. This is done to incr ...

A protocol similar to RS232 which permits data interchange on multidrop networks of up to 32 nodes using a single twisted pair cable. In order for this protocol to be used, each device on a network must have some level of intelligence in order establish o ...

A set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.

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

In general, solar radiation received at the earth's surface. Contracted from incoming solar radiation.

An air-launched balloon designed to be released in the eye of a tropical cyclone, float within the eye at predetermined levels, and transmit radio signals for RDF positioning.

The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.

Winds which, over a small area, differ from those which would be appropriate to the general pressure distribution.

A type of rain gauge shield consisting of freely hanging, evenly spaced slats arranged circularly around the gauge. The advantage of this shield is that the slats do not easily accumulate snow, permitting its use on unattended gauges. See rain gauge shiel ...

Determination of the total amount of snow covering a watershed or a given region. Both depth and water content of the snow may be measured, and the results may be used to predict the amount of water that will be available after melting.

Moisture contained in the soil above the water table, including water vapor which is present in the soil pores. In some cases this term refers strictly to the humidity contained in the root zone of plants.

Same as dew-point hygrometer.

General term for any device that measures precipitation: principally a rain gauge or snow gauge.

In general, the transformation of data from a "raw" form to some useable form. In meteorology, this often refers to the conversion of the observed value of an element to the value which it would theoretically have at some selected or standard level. The m ...

Same as atmometer.