W

warm front
A front in which a warm air mass replaces a cold air mass.
water column
A vertical column of ocean water, divided into different zones according to their depth.
water purification
Any process used to produce safe drinking water by removing contaminants.
water table
The upper surface of ground water.
water vapor
Water in the form of a gas. Water vapor is invisible to humans; when we see clouds, we actually are seeing liquid water in the clouds.
wave
A change in the shape of water caused by energy from wind.
wave-cut cliff
A sea cliff cut by strong wave energy.
wave-cut platform
Level area formed by wave erosion as waves undercut cliffs.
wavelength
Horizontal distance from wave crest to wave crest, or wave trough to wave trough.
weather
The temporary state of the atmosphere in a region.
weather map
A map showing weather conditions over a wide area at a given time.
weathering
The chemical or physical breakdown of rocks, soils or minerals at Earth’s surface.
well
A circular hole that goes into an aquifer to allow people to access groundwater.
wetland
Lands that are wet a large amount of the time.
white dwarf
A small to mid-sized star that has collapsed.