ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Terminology of Radiation Balance

Updated on January 17, 2014

Radiation Budget: The temperature of the Earth’s surface, atmosphere and oceans and the rate of change of those temperatures depends on the detailed balance of energy fluxes; commonly referred to as the ‘Radiation Budget/Balance’,

Energy balance: The difference between the total incoming and total outgoing energy. If this balance is positive, warming occurs; if it is negative, cooling occurs.

Radiation: Radiation is the propagation and emission of energy in the form of electromagnetic waves. The types of radiation include, light, heat and sound.

Short-wave Radiation: Shortwave radiation (SW) is the radiant energy with wavelengths in the visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) spectra. In broad sense we may defined it to all radiation with a wavelength between 0.1μm and 5.0μm.

Long-wave Radiation: Longwave radiation is the infrared energy emitted by the earth and atmosphere at wavelengths between about 5 and 25 micrometers.

Wavelength: Forms of electromagnetic radiation like radio waves, light waves or infrared (heat) waves make characteristic patterns as they travel through space. Each wave has a certain shape and length. The distance between peaks (high points) is called wavelength.

Solar Radiation: Solar radiation is the electromagnetic radiation emitted by the Sun. Almost all known physical and biological cycles in the Earth system are driven by the solar radiation reaching the Earth.

Solar Spectrum: The distribution of solar radiation as a function of the wavelength is called the solar spectrum, which consists of a continuous emission with some superimposed line structures.

Solar Constant: The solar constant is the amount of solar radiation received outside the Earth’s atmosphere on a surface normal to the incident radiation per unit time and per unit area at the Earth’s mean distance from the Sun.

Solar Insolation: The solar insolation is the actual amount of solar radiation incident upon a unit horizontal surface over a specified period of time for a given locality.

Direct Solar Radiation: The radiation coming directly from the Sun received at the Earth’s surface is called direct solar radiation.

Diffuse Solar Radiation: The amount of scattered radiation coming from all other directions is called diffuse solar radiation.

Terrestrial Radiation: Long-wave electromagnetic radiation originating from Earth and its atmosphere. It is the radiation emitted by naturally radioactive materials on Earth including uranium, thorium, and radon.

Net Radiation: Difference in intensity between all incoming energy and all outgoing energy carried by both shortwave and longwave radiation.

Flux: Rate of energy transfer by electromagnetic radiation.

Radiant Flux Density: The radiant flux density is the amount of radiant flux (or power) crossing a unit of area, and is measured in W m-2. Radiant flux density is also known as intensity or irradiance.

Blackbody Radiation: the electromagnetic radiation that would be radiated from an ideal black body; the distribution of energy in the radiated spectrum of a black body depends only on temperature and is determined by Planck's radiation law.

Emissivity: The emissivity of a surface is defined as the ratio of the radiation emitted by the surface to the radiation emitted by a blackbody at the same temperature. Thus,

0≤ ε≤1

Absorptibity: Absorptivity is the fraction of irradiation absorbed by the surface.

Reflectivity: Reflectivity is the fraction of irradiation reflected by the surface.

Transmissivity: Transmissivity is the fraction of irradiation transmitted through the surface.

Radiosity: total radiation energy streaming from a surface, per unit area per unit time. It is the summation of the reflected and the emitted radiation.

Diffuse surface: Diffuse surface is a surface which its properties are independent of direction.

Gray surface: Gray surface is a surface which its properties are independent from wavelength.

Sensible Heat Flux: The flux of heat from the Earth’s surface to the atmosphere that is not associated with phase changes of water; a component of the surface energy budget.

Latent Heat Flux: The flux of heat from the Earth’s surface to the atmosphere that is associated with evaporation or condensation of water vapour at the surface; a component of the surface energy budget.

Soil Heat Flux: The amount of heat flowing into a cross-sectional area of soil per unit time.

The Principle of Conservation of Energy: A principle stating that the total energy of an isolated system remains constant regardless of changes within the system.

Heat Capacity: The ratio of the heat energy absorbed by a substance to the substance's increase in temperature.

Specific Heat: The amount of heat, measured in calories, required to raise the temperature of one gram of a substance by one Celsius degree.

Evaporation: The process by which a liquid becomes a gas.

Evapotranspiration: The combined process of evaporation from the Earth’s surface and transpiration from vegetation.

Condensation: The process by which a gas or vapor changes to a liquid.

Ideal Surface: An ideal solid surface is one that is flat, rigid, perfectly smooth, chemically homogeneous, and has zero contact angle hysteresis.

Albedo: Some of this incoming flux is reflected straight back to space by the atmosphere, the clouds and the Earth’s surface. The fraction of the radiation that is reflected is called the albedo of the Earth or planetary albedo (α). In present-day conditions, it has a value of about 0.3.

Surface Temperature: Surface Temperature is the temperature of the atmosphere which represents the average kinetic energy of the molecular motion in a small region and is defined in terms of a standard or calibrated, thermometer in thermal equilibrium with the air.

Air temperature: The temperature describes the kinetic energy, or energy of motion, of the gases that make up air. As gas molecules move more quickly, air temperature increases.

Bowen Ratio: The ratio of sensible to latent heat fluxes from the Earth’s surface up into the atmosphere.

Horizontal surface: a flat surface at right angles to a plumb line.

Absorption: Absorption is a process by which incident radiant energy is passed to the molecular structure of a substance.

Scattering: Is an atmospheric process where small particles and gas molecules diffuse part of the incoming solar radiation in random directions without any alteration to the wavelength of the electromagnetic energy.

Solar thermal: Solar thermal is the conversion of solar radiation into thermal energy (heat). Thermal energy carried by air, water, or other fluid is commonly used directly, for space heating, or to generate electricity using steam and turbines.

Blackbody: A blackbody is defined as a perfect em itter and absorber of radiation. At a specified temperature and wavelength, no surface can emit more energy than a blackbody.

Irradiance: Irradiance is the power of electromagnetic radiation per unit area (radiative flux) incident on a surface. Radiant emittance or radiant exitance is the power per unit area radiated by a surface. The SI units for all of these quantities are watts per square meter (W/m2).


IPCC, 2003: Definitions and Methodological Options to Inventory

Emissions from Direct Human-Induced Degradation of Forests and Devegetation of Other Vegetation Types [Penman, J., et al. (eds.)]. The Institute for Global Environmental Strategies (IGES), Japan, 32 pp.

Taylor F.W. (2005). Elementary Climate Physics. Oxford University Press. 212pp

Trenberth K.E. and J.M. Caron, (2001). Estimates of meridional atmosphere and ocean heat transport. Journal of Climate 14: 3433-3443.

Trenberth, K. E., J. T. Fasullo and J. Kiehl (2009). Earth's global energy budget. Bull. Amer. Meteor. Soc., 90: 311-323.

Wallace J.M. and P.V. Hobbs (2006). Atmospheric science: an introductory survey (2nd edition). International Geophysics Series 92, Associated press, 484pp.

R Goody and H Hu, Absorption and Thermal Emission Harvard University, Cambridge,


AMS, 2000: AMS Glossary of Meteorology, 2nd Ed. American Meteorological Society, Boston, MA,


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)