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

A measure of luminous flux remaining in a light beam after it has passed through a specified distance of the atmosphere.

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

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

Wind with a speed between 17 and 21 knots (19 and 24 mph); Beaufort scale number 5.

Read Only Memory. A memory that cannot be altered in normal use of a computer, Usually used to store information permanently, such as firmware programs.

An accumulation of granular ice tufts on the windward sides of exposed objects that is formed from supercooled fog or cloud and built out directly against the wind.

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

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 ...

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

That portion of the record of a microbarograph between any two (or a specified small number) of successive crossings of the average pressure level (in the same direction). Analogous to microseism.

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

For a given location, a measure of the long-range effectiveness of precipitation in promoting plant growth. Also called precipitation-evaporation index.

A strong wind characterized by a sudden onset, a duration on the order of minutes, and a rather sudden decrease in speed.

The process by which water in plants is transferred as water vapor to the atmosphere. Also, the amount of water so transferred.

Same as Aeolian.

A hygrometer which includes an arrangement for the time recording of atmospheric humidity.

Thermodynamic change of state of a system in which there is transfer of heat across the boundaries of the system. Compare to adiabatic process.

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 ...

An anemometer which measures wind speed by means of the properties of wind-borne sound waves. It operates on the principle that the propagation velocity of a sound wave in a moving medium is equal to the velocity of sound with respect to the medium plus t ...