| GLOSSARY |
Our comprehensive earth science glossary is available to assist in your understanding of the MY NASA DATA microsets, lesson plans and computer tools. Please select the first letter of the word you wish to check for a definition and further information. |
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| radiation: |
| energy that is emitted from a source in the form of rays or waves. Solar and terrestrial radiation are said to be electromagnetic, made up of oscillating electric and magnetic fields which propogate at the speed of light. Solar radiation is shortwave and terrestrial radiation is longwave.
More about electromagnetic waves
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| radiosonde: |
| a weather balloon and receiver system used to collect a vertical profile of data, usually temperature, dew point temperature and atmospheric pressure at a particular time and location. The data is often used as input for numerical forecast models and local severe weather forecasting. Some radiosondes are also equipped to measure the speed and direction of winds (rawinsondes) or ozone (ozonesondes).
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| rainshadow effect: |
| the reduction of precipitation commonly found on the leeward side of a mountain range. The reduction in precipitation is the result of descending air that warms and reduces convection and condensation.
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| Rayleigh scattering: |
| In the 19th century, Lord Rayleigh theorized that the sky is blue because our atmosphere causes the sun's light to bend or scatter into the colors of the visible light spectrum, thus we see blue because blue light scatters more than do other colors of light.
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| reflection: |
| the return of sound or light back to its source. In the atmosphere, the process where incoming solar rays are redirected back upwardly after striking particles. Cloud water and ice account for most reflection of solar radiation.
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Image courtesy University of Virginia |
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| reflectivity: |
| The fraction of radiation (for example, light) reaching a surface that is reflected by that surface. A mirror has a very high reflectivity, near 1. In contrast, black objects generally have a very low reflectivity. A perfect blackbody (see definition) would have a reflectivity of 0..
Surface Reflectivity
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| refraction: |
| the redirection of light after entering a medium; in the atmosphere, solar rays are redirected by interactions with air, cloud and aerosol particles.
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| relative humidity: |
| the ratio between the amount of water vapor in the air and the amount required for saturation; depends on atmospheric temperature and pressure.
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| renewable energy: |
| energy that can be replenished in a short period of time such as energy from solar, wind, water or geothermal sources. Typically, there is little concern that these sources of energy will become scarce or used up, unlike fossil fuels.
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| resolution: |
| refers to the separation of data points, whether in space or in time. See also pixel.
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