• 30-year historical normal — A statistically adjusted 30-year average officially published by the National Oceanic and Atmospheric Administration every 10 years; also called a "climate normal."

A

• Agribusiness — Farming engaged in as a large-scale business operation embracing the production, processing, and distribution of agricultural products and the manufacture of farm machinery, equipment, and supplies.
• Albedo — The fraction of incoming radiation that is reflected.

B

• Barometer — An instrument for determining the weight or pressure of the atmosphere.
• Barometric pressure — Atmospheric pressure as indicated by a barometer.

C

• Climate — The accumulation of daily and seasonal weather events over a long period of time.
  Click here for information about the climate of North Carolina.
• Convection — Heat transfer in which mass is exchanged. A net movement of mass may occur, but more commonly parcels with different energy amounts change places, so that energy is exchanged without a net movement in mass.
• Coriolis force — An apparant force which acts solely from the earth's rotation to deflect parcels or objects. It is a function of latitude and speed of object.

D

• Degree days — A unit used in estimating fuel requirements for heating a building.
• Disaster mitigation — Process of lessening the impacts of disasters.
• Drought — A period of abnormally dry weather sufficiently long enough to cause serious effects on agriculture and other activities in the affected area.
  Click here for information about drought in North Carolina.

E

• El Niño — An extensive ocean warming that begins along the coast of Peru and Ecuador. Major El Niño events occur once every 3 to 7 years as a current of nutrient-poor tropical water moves southward along the west coast of South America.
  Click here for information about El Niño.
• Energy balance — A condition in which the energy budget is balanced; the system neither gains nor loses energy.
• Energy budget — Measure of energy entering and leaving a system, such as Earth's climate system.

G

• Gage height — The height of water in a river or stream above a reference point. In other words, gage height measures the elevation of a water surface (in feet) at a given location.
• Global teleconnections — Links between changes in weather environmental conditions between distant geographical locations.
• Groundwater — Water that seeps into the ground and saturates soil or rock. Groundwater is measured based upon the depth (in feet) at which water is first found below the earth's surface.
• Growing degree days — A form of the degree-day used as a guide for crop planting and for estimating crop maturity dates.

H

• Heat flux — The amount of heat transferred in the atmosphere per unit of time through a unit of area.
• Horticulture — The science or art of cultivating fruits, vegetables, flowers, or ornamental plants.
• Hurricane — A severe tropical cyclone having winds in excess of 64 knots (74 mph).
  Click here for information about hurricanes in North Carolina.

L

• La Niña — A condition where the central and eastern tropical Pacific Ocean turns cooler than normal.
  Click here for information about La Niña.
• Lapse rate — Rate of decline of temperature with height in the atmosphere.
• Latent heat — The heat energy required to change a substance from one state to another. It is an important source of atmospheric energy, especially for storms, such as thunderstorms and hurricanes.

M

• Mesoscale circulations — Horizontal atmospheric circulation on the order of 10 to 1000 km.

N

• Numerical model — A model expressed in mathematical formulas and solved approximately on a computer.

P

• Percentile — The rank of a particular value, in a dataset, on a percentage scale from 1 to 99, where the 1st percentile represents the lowest value (minimum), and the 99th percentile represents the highest value (maximum).
• Photosynthetically active radiation — Specific spectrum of so radiation used by plants in the photosynthesis process.

S

• Season — Expressed in terms of the declination angle of the sun, which is the latitude of the point on the surface of the Earth directly under the sun at noon.
• Solar Radiation — Total radiation from the sun.
• Storm surge — An abnormal rise of several meters in the ocean level. It is produced by the combination of high water and high winds.
• Streamflow — A measure of the volume of water that flows past a given point in a river or steam, recorded in cubic-feet per second. Another name for streamflow is discharge. Peak streamflow refers to the highest instantaneous streamflow measurement for a given year.

T

• Temperature inversion — A region of negative lapse rate where the temperature increases with altitude.
• Thermohaline circulation — In the ocean, when temperature and salinity act together. It is a vertical circulation induced by surface cooling, which causes convective overturning.
• Topography — The natural and manmade features and relief of Earth's surface.
• Tornado — An intense, rotating column of air that protrudes from a cumulonimbus cloud in the shape of a funnel or a rope whose circulation is present on the ground.
  Click here for information about tornadoes in North Carolina.
• Tropical cyclone — A violent storm originating over tropical or subtropical waters, characterized by violent rainstorms and high-velocity cyclonic winds.
• Tropical depression (TD) — A mass of thunderstorms and clouds generally with a cyclonic wind circulation between 20 and 34 knots (23-49mph).
• Tropical storm (TS) — Organized thunderstorms with a cyclonic wind circulation between 35 and 64 knots (40-74 mph).
• Troposphere — The atmospheric layer from Earth's surface to the tropopause; that is, the lowest 10-20km of the atmosphere where most weather occurs.

U

• Undulation — A wavelike form, outline, or appearance.