HOPKINS GLOSSARY OF WEATHER TERMS W

water vapor channel

wavelength

• The distance between successive maxima (crests) or minima (troughs) of a wave train, measured along the direction of wave propagation. The wavelength is one of the ways used to identify wave phenomena. Wavelength units are units of distance, such as micrometers or meters.

weather radar

weather satellite

wet-bulb temperature

• The final temperature attained by the wetted muslin covered wet bulb thermometer of a psychrometer when thoroughly ventilated. The lowest temperature that an air parcel would have if cooled adiabatically to saturation at constant pressure by evaporation of water into it, assuming that all latent heat required for evaporation would be supplied by the air parcel itself. The units for wet bulb temperature are the same for air temperature. Contrast with dry-bulb temperature.

wet-bulb thermometer (or wet-bulb)

• The thermal sensor in a psychrometer that has a muslin covered bulb which is saturated with water and then ventilated thoroughly to attain the wet-bulb temperature. Contrast with dry-bulb thermometer.

wind

• Air in motion relative to the earth's surface, caused by the average movement of a "large number" of molecules of air, usually with scales larger than the random motions of individual molecules; often refers only to the horizontal motion because vertical wind components, especially near the earth's surface are relatively small.

wind profiler

• The wind profiler is an array of Doppler radar units that measures and displays wind information (wind speed and direction) from the earth's surface up to an altitude of 16 km. These instruments are generally used to detect low level wind shear.

wind shear

• The difference between wind velocity measured at two specific locations divided by the distance between those two positions; wind shear consists of a combination of speed shear and directional shear.

wind vane

• Any instrument designed primarily to measure wind direction .

wind velocity

• A vector quantity that describes wind motion in terms of wind speed and wind direction.