An aviation weather forecast for a specific flight.

Hygrometer in which the dew (frost) point is determined by observing the temperature of an artificially cooled surface at the moment at which dew (frost) first appears on it.

Transistor-Transistor Logic.

An instrument which measures the rate of evapotranspiration. It consists of a vegetation soil tank so designed that all water added to the tank and all water left after evapotranspiration can be measured.

A vent used with pressure sensors to reduce the effect of wind on the pressure inlet. It is normally mounted remotely and connected to the sensor using airtight tubing.

Same as aneroid barometer. Holostelic means wholly made of solids, while aneroid means devoid of liquid.

An anemometer in which the sensor rotation is transmitted to a mechanical counter which directly integrates the air movement past the sensor. Used to determine total air passage (wind run). Average wind speed can be calculated from the difference between ...

A momentary decrease in the speed of the wind.

Wind with a speed between 41 and 47 knots (47 and 54 mph); Beaufort scale number 9.

The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve. Usually expressed as a percentage of full- scale range.

The closeness of agreement among a number of consecutive output values measuring the same input value under the same operating conditions, approaching from the same direction. Usually measured as nonrepeatability but expressed as repeatability, a percenta ...

Similar to the spectroheliograph, but used for visual instead of photographic purposes.

An early and once universal name for the mercury barometer.

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.

Any emission of light at temperatures below that required for incandescence.

Same as dew-point hygrometer.

The change in barometric pressure within a specified period of time (typically 3 hours for meteorological observations).

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

In meteorology, an area of low pressure; a low or trough.

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.