Understanding Key Environmental and Soil Science Terms

Precipitation

All forms of water that fall to Earth, including rain, snow, hail, sleet, fog, mist, drizzle, and the measured amounts of each.

Rain Shadow

A dry region on the leeward side of a mountain range resulting from a reduction in rainfall.

Runoff

The draining away of water.

Soil

Soil is the medium for plant growth, the principal factor controlling the fate of water in terrestrial environments, nature's recycling system (which breaks down the waste products of plants and animals and transforms them into their basic elements), and a habitat to a diversity of animal life, from small mammals to countless forms of microbial life.

Short-Day Plant

A plant that flowers only after being exposed to light periods shorter than a certain length, typically in early spring or fall.

Soil Horizon

A major zone or layer of soil with its own particular structure and characteristics.

Surface Tension

An elastic film across the surface of a liquid, caused by the attractive forces between molecules at the surface of the liquid.

Temperature

A measure of the average speed or kinetic energy of atoms and molecules in a substance.

Trade Winds

Tropical easterly winds that blow in a steady direction from the subtropical high-pressure areas to the equatorial low-pressure areas between latitudes 30 and 40 degrees north and south. They are generally northeasterly in the Northern Hemisphere and southeasterly in the Southern Hemisphere.

Transpiration

The loss of water vapor from a plant to the outside atmosphere.

Weathering

The physical and chemical breakdown of rock and its components at and below Earth's surface.

Water Cycle

The movement of water between the atmosphere and Earth by way of precipitation and evaporation.

Weather

The combination of temperature, humidity, precipitation, wind, cloudiness, and other atmospheric conditions at a specific time and place.

Westerlies

The dominant east-to-west motion of the winds centered over the middle latitudes of both hemispheres.

Andisols

Soils with volcanic parent material that are not highly weathered; upper layers are dark-colored with low bulk density.

Aridisols

Soils found in very dry environments, low in organic matter, high in base content, and prone to the process of salinization.

Entisols

Immature soils that lack vertical development of horizons, associated with recently deposited sediments.

Histosols

Soils with a high content of organic matter, formed in areas with poor drainage; bog and muck soils.

Mollisols

Soils with surface horizons that are dark brown to black with a soft consistency, rich in bases; soils of semihumid regions prone to the process of calcification.

Oxisols

Highly weathered soils with a nearly featureless profile, red, yellow, or gray in color, rich in kaolinite, iron dioxides, and often humus; found in tropical and subtropical regions.

Ultisols

Intensely leached soils with strong clay translocation and low base content; found in humid, warm climates; formed by the process of laterization.

pH influences the availability of nutrients and restricts the environment of organisms sensitive to acidic conditions.