Initial Publication Date: July 5, 2011

Climate Glossary


to enter a body. For example, radiation from the sun is absorbed by the surface of the earth, water or the atmosphere.


the process in which something takes in a substance or energy.


a measure of the reflectivity of a surface ranging from 0 to 1; albedo is calculated by taking the ratio of reflected radiation to incoming radiation, such that a surface that reflects 100% of light hitting it has an albedo of 1 and a surface that absorbs 100% of the light hitting it has an albedo of 0.


a component of biodiversity indicating how common or rare a species is relative to other organisms in an ecosystem


the capacity of an organism to thrive in its ecosystem. E.g. Desert plants have thick leaves that hold water, an adaptation to hot and dry climate.


adjustment in natural or human systems to a new or changing environment.

air mass

an extensive body of air throughout which the horizontal temperature and moisture characteristics are similar.

angle of incidence

an angular measurement of an object away from 'straight up.' Ex. If a flag pole is perpendicular to the ground it has an angle of incidence of '0'. If it is tilted to one side it's angle of incidence is the degrees away from perpendicular.


irregularity or deviation from normal.


made by people or resulting from human activities. Usually used in the context of emissions that are produced as a result of human activities.


the diversity of a region based on the number and kinds of different plant and animal organisms.


communities of plants and animals that are defined geographically and climatically. For example, rainforests are a biome defined as warm all year round with plenty of rain and sunlight, generally found near the equator with lush plant growth and a diversity of animals.


a region's long-term, average weather elements such as temperature and precipitation. The climate generally determines what kind of plants will grow in that region.

climate change

a significant and long-term change in the weather patterns over periods ranging from decades to thousands of years. The change may range over a specific region or the entire Earth.


the process where a substance reacts with oxygen and gives off heat and light.


the amount per unit volume or area. When discussing sea ice it refers to the percent of water surface covered by ice.


in general, the physical process by which a vapor (gaseous state of a liquid) becomes a liquid; the opposite of evaporation.


the use of something such as food or energy.


to reduce in size.

convection currents

one of the major modes of heat transfer by the movement of mass, liquid or gas.


decaying or breaking into pieces. The process of a material separating into two or more things that may differ from each other and the original material.


the calculated mass per unit volume of a substance. Less dense fluids and gases float on denser fluids and gases, unless they mix. Hot air is less dense than cold air, which is why hot air balloons rise.


how biological organisms, plants or animals, are geographically arranged. The distribution of some species may be continent wide or limited to a specific valley or mountain top.


the number of species, plant and animal, in a region as well as their relative abundance.


a geographical region defined by all the living organisms (biotic) as well as the nonliving (abiotic) components such as climate, topography and geology.

electromagnetic spectrum

the range of all possible frequencies of electric radiation. Short frequency waves such as x-rays are high energy, long frequencies such as radio waves are low energy.


the height above a fixed reference. The most commonly used reference is sea level.


an indirectly observed quantity, it is usually defined as the ability to do work. Energy can be stored or transferred and like mass is considered important to be conserved.


refers to the region near the Equator of the planet.


occurs twice a year on a day in March and September, when the tilt of the Earth is neither towards, nor away from the sun. On these two days, the day length and night length equal 12 hours.


the physical process by which a liquid, such as water, is transformed into a gaseous state, such as water vapor. It is the opposite physical process of condensation.


incremental change in an organism over time.


increase in size.


the range, magnitude, or distance that something covers. When discussing sea ice, it refers to how many square miles of ice there is or how far away from the center the ices reaches.


species of organisms that once lived on Earth but are no longer present. Examples are the large dinosaurs as well as more recent additions to the list, such as the passenger pigeons and the great auk.

food chain

the sequence of who eats who in an ecosystem. Primary producers (plants) use the energy from the sun to create food, primary consumers (animals) eat the plants and secondary consumers eat the primary consumers. Grass – rabbit - fox is a simple food chain.

food web

a complex system of who eats who in an ecosystem More than one consumer may eat an organisms giving rise to a web of food chains; that is, several food chains present in an ecosystem will invariably interconnect and create a food web.


preserved remains or evidence of plants and animals from the past.


the transition zone or interface between two air masses of different densities, which usually means different temperatures. For example, the area of convergence between warm, moist air and cool, dry air.


a large body of ice spreading over the land, down a mountain slope or through a valley.

greenhouse effect

the overall warming of Earth's lower atmosphere primarily due to carbon dioxide and water vapor, which permit the Sun's rays to heat Earth, but then restrict some heat-energy from escaping back into space.


the environment where a plant or animal normally lives and grows.

hadley cells

a direct, thermally driven and zonally symmetric circulation under the strong influence of Earth's rotation, first proposed by George Hadley in 1735 as an explanation for the trade winds. It consists of the equator-ward movement of the trade winds between about latitude 30° and the equator in each hemisphere, with rising wind components near the equator, pole-ward flow aloft, and, finally, descending components at about latitude 30° again.

hydrologic cycle

the process of evaporation, vertical and horizontal transport of vapor, condensation, precipitation, and the flow of water from continents to oceans. It is a major factor in determining climate through its influence on surface vegetation, the clouds, snow and ice, and soil moisture. The hydrologic cycle is responsible for 25 to 30 percent of the mid-latitudes' heat transport from the equatorial to polar regions.

ice sheets

great ice masses covering both Greenland and Antarctica.


to pass through a substance by filtering or permeating. Water infiltrates through soil, sand and gravel.


the long wave, electromagnetic radiation of radiant heat emitted by all hot objects. On the electromagnetic spectrum, it can be found between microwave radiation and visible light. Water vapor, ozone, and carbon dioxide are capable of absorbing or transmitting infrared radiation. May be referred to as IR.


the amount of solar radiation received by Earth in a given area in a given time. It is usually expressed as watts per square meter, (W/m2).

kinetic energy

energy of motion.

land use

human modification and management of land, such as agriculture, homes, or other development.

latent heat

the energy required to change a substance to a higher state of matter (solid to liquid to gas). This same energy is released from the substance when the change of state is reversed (gas to liquid to solid).


circular lines around Earth that measure the angular distance from the Equator in degrees. The Equator is 0˚ latitude, and divides Earth into the Northern and Southern hemispheres.


the angular distance along the equator measured from the prime meridian to the meridian of the point in question.


the study of atmospheric phenomenon, usually used in reference to the study of weather.


to move from one region to another usually seasonally for breeding or feeding.


the act of reducing the severity of something.


a mathematical representation of a process, system, or object developed to understand its behavior or to make predictions. The representation always involves certain simplifications and assumptions.

ocean current

a continuous and directed movement of the oceans water due to winds, waves, temperature, density or the movement of the Earth.


ozone is a form of oxygen made up of three atoms of oxygen rather than the usual two. It forms a protective layer high up in the stratosphere that absorbs some of the ultraviolet (UV) radiation from the sun. Too much UV radiation can cause health problems and damage plants.


past or ancient climates.


the slow passage of a liquid through a filtering medium, such as soil or gravel.


periodical natural events that are correlated with climate and seasonal cycles. Examples include: flowers blooming, insects hatching, fish spawning, leaves turning color, maple sap running.


a process occurring in plants which takes the energy of the Sun, carbon dioxide, and water and produces sugars and other plant tissues.


refers to the regions of Earth near the poles.


any and all forms of water, liquid or solid, that falls from clouds and reaches the ground. This includes drizzle, freezing drizzle, freezing rain, hail, ice crystals, ice pellets, rain, snow, snow pellets, and snow grains. The amount of fall is usually expressed in inches of liquid water depth of the substance that has fallen at a given point over a specified time period.

proxy data

proxy data is data that paleoclimatologists gather from natural recorders of climate variability, e.g., tree rings, ice cores, fossil pollen, ocean sediments, coral and historical data. By analyzing records taken from these and other proxy sources, scientists can extend our understanding of climate far beyond the 140-year instrumental record.


the change in direction of waves as they interact with a substance. Common waves are water, sound and light.


referring to the amount of dissolved minerals in water, usually salt specifically.


an imagined or projected sequence of events, especially any of several detailed plans or possibilities.

sea ice

sea water that freezes. Because of the salt content of the oceans, the freezing point is below 0°C.

sea level

the average height of the ocean's surface, used as a standard for measuring the elevation of land.

semi- permanent pressure systems

a relatively stable, stationary, pressure-and-wind system where the pressure is predominately high or low with the changing season. They are not of a transitory nature, like migratory lows that develop from temperature and density differences.

sensible heat

the excess radiative energy that has passed from Earth's surface to the atmosphere through advection, conduction, and convection processes.

solar radiation

the electromagnetic radiation coming to Earth from the Sun. Is also called sunshine.


an event that occurs twice a year when Earth's tilt causes the Sun to reach the most northern and most southern extremes.


a detailed description of the plot or sequence of events.


stratocumulus clouds are usually large and rounded. They seldom produce precipitation, but often indicate that a storm is coming.


the layer above the troposphere and below the mesosphere. The ozone layer is located here and temperature increases slightly with altitude.


the process of phase transition from solid directly to vapor in the absence of melting. For example, an ice crystal or icicle sublimes under low relative humidity at temperatures below 0°C. The process is analogous to evaporation of a liquid.


a physical property of matter that directly relates to the amount of energy is contained by the matter. Matter with a high amount of energy is considered warmer than matter containing a low amount of energy.


thermo = heat, haline = salinity. The thermohaline circulation of the oceans refers to the deep water current that is driven by cold, dense, salty water and warm surface waters.


the shape and features of Earth's surface E.g. Mountains, valleys, and plains.


the process by which water in plants is transferred as water vapor to the atmosphere.


the lowest layer of the atmosphere and where weather occurs.


the state of the atmosphere at a given location and time. It includes such variables as temperature, precipitation, cloudiness, wind speed and direction, and relative humidity.


air that flows in relation to Earth's surface, generally horizontally. There are four areas of wind that are measured: direction, speed, character (gusts and squalls), and shifts. Surface winds are measured by wind vanes and anemometers, while upper level winds are detected through pilot balloons, radiosonde for wind, or aircraft reports.

Climate Glossary References and Additional Resources

Use the following links to locate additional definitions for weather and climate terminology.

AMS Glossary of Meteorology

EPA Glossary of Climate Change

NASA Earth Observatory Glossary

U.S. Climate Resilience Toolkit Glossary