Glossary

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Warm Desert -  Desert found in the subtropics or interiors of continents at the middle latitudes where precipitation is low and surface air temperatures are high.
Warm Front -  A transition zone in the atmosphere where an advancing warm air mass displaces a cold air mass.
Wash -  (1) Coarse alluvial sediments. (2) The downslope movement of small particles of soil by overland flow. Also called sheetwash. (3) A term used in the United States for a shallow intermittent stream channel found in arid and semi-arid regions.
Water Consumption -  The complete removal of water from some type of source, like groundwater, for some use by humans. This water is not returned to the source. Compare with water withdrawal.
Water Table -  Top surface of groundwater.
Water Withdrawal -  The removal of water from some type of source, like groundwater, for some use by humans. The water is subsequently returned some period of time later after its is used. The quality of the returned water may not be the same as when it was originally removed. Compare with water consumption.
Waterfall -  (1) A location in the long profile of a stream where water flows vertically. A nickpoint. (2) Verical drop in elevation that causes a stream's dischange to flow vertically.
Watershed -  Catchment area of a drainage basin.
Watershed -  The topographic ridge that separates drainage basins.
Waterspout -  A vortex of rapidly moving air over water that is associated with some thunderstorms.
Wave -  A moving swell or ridge on the surface of a solid or liquid or within the medium of a gas. Electromagnetic radiation also travels in waves.
Wave Crest -  The curved tops or ridges of an oscillating wave.
Wave Cyclone -  Another name for mid-latitude cyclone.
Wave Height -  Vertical distance between a wave's trough and crest.
Wave Period -  The time elapsed for a wave to travel the distance of one wavelength.
Wave Refraction -  The re-orientation of a wave so that it approaches a shoreline at a more perpendicular angle. This process is caused by the differential reduction of water depth as a linear wave approaches a curved shoreline. A reduction in water depth causes a wave to slow down causing the waves approaching a nonlinear shoreline to curve with the shore's shape.
Wave Trough -  Area in between wave crests.
Wave-Cut Notch -  A rock recess at the foot of a sea cliff where the energy of water waves is concentrated.
Wave-Cut Platform -  A flat or slightly sloping bedrock surface that forms in the tidal zone. Caused by wave erosion.
Wavelength -  Distance between two successive wave crests or troughs.
Weather -  The state of the atmosphere at a specific time and place.
Weather Map -  Map that displays the condition of the physical state of the atmosphere and its circulation at a specific time over a region of the Earth.
Weathering -  Physical, chemical or biological breakdown of rocks and minerals into smaller sized particles.
Weathering Landform -  Is a landform created by the physical or chemical decomposition of rock through weathering. Weathering produces landforms where rocks and sediments are decomposed and disintegrated. This includes landforms with some of the following geomorphic features: karst, patterned ground, and soil profiles.
Westerlies -  Dominant winds of the mid-latitudes. These winds move from the subtropical highs to the subpolar lows from west to east.
Wet Adiabatic Lapse Rate -  The rate of decline in the temperature of a rising parcel of air after it has reached saturation. This rate is less than the dry adiabatic lapse rate (9.8° Celsius per 1000 meters) because of the heat energy added to the ascending air parcel from condensation and deposition processes.
Wet Deposition -  The transport of gases and minute liquid and solid particles from the atmosphere to the ground surface with the aid of precipitation or fog. Compare with dry deposition.
Wet-Bulb Depression -  The value calculated by subtracting a wet-bulb thermometer reading from a dry-bulb thermometer reading. Used to determine the air's relative humidity or dew point from a psychrometric table.
Wet-Bulb Thermometer -  Thermometer on a psychrometer that has a moisten wick on its reservoir bulb. When ventilated this thermometer records a temperature that is modified by the cooling effects of evaporation. This measurement and the temperature reading from a dry-bulb thermometer are then used to determine the air's relative humidity or dew point from a psychrometric table.
Wetland -  Natural land-use type that is covered by salt water or fresh water for some time period. This land type can be identified by the presence of particular plant species or characteristic conditions.
Wetting and Drying -  Physical weathering process where rocks are mechanically disintegrated by the accumulation of successive layers of water molecules in between the mineral grains of a rock. Sometimes called slaking.
Wind -  Air moving horizontally and/or vertically.
Wind Ripples -  Wind ripples are miniature sand dunes between 5 centimeters and 2 meters in length and 0.1 to 5 centimeters in height. They are created by saltation when the sand grains are of similar size and the wind has a constant speed. Also called sand ripples.
Wind Vane -  A mechanical device used to measure the direction of wind flow. Usually consists of a horizontal bar with a fin at one end and a aerodynamic pointer at the other end. The center of horizontal is attached to a vertical spindle which is connected to a mechanical device that records direction.
Windward -  Upwind side or side directly influenced to the direction that the wind blows from. Opposite of leeward.
Winter -  Season between fall and spring. Astronomically it is the period from the winter solstice to the vernal equinox in the Northern Hemisphere.
Winter Solstice -  The winter solstice denotes the first day of the winter season. For the Northern Hemisphere, the date of winter solstice is either on December 21 or 22 (changes yearly). June 21 or 22 is the date of the winter solstice for the Southern Hemisphere. During the winter solstice, locations in their respective hemispheres experience the shortest day of the year.