| 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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| SAGE III: |
| Stratospheric Aerosol and Gas Experiment is one of the scientifc satellite instruments developed for NASA's Earth Observing System (EOS). SAGE III's role is to provide global, long-term measurements of key components (aerosols and ozone) of the Earth's atmosphere. Measurements are taken from the uppper troposphere through the stratosphere.
SAGE III Science Team Website
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Image courtesy The SAGE III Science Team |
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| satellite: |
| Something that is in orbit around something else. For example, the Moon is a natural satellite in orbit around the Earth. Terra and Aqua are artificial satellites put into Earth orbit. The Mars Reconnaissance Orbiter is an artificial satellite put into orbit around Mars.
Satellite Tracking site
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Image courtesy NASA |
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| saturation: |
| the atmospheric condition when water will begin to change phase from vapor to liquid or solid; occurs when relative humidity reaches 100 percent, usually by cooling.
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| scanning instrument: |
| An instrument which is attached to a spacecraft on an assembly that is designed to move. The field of view of a scanning instrument sweeps back and forth across the Earth under the satellite's path, or using some other pre-determined pattern.
The ERBE scanning instrument
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Image courtesy NASA |
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| scatter plot: |
| a plot used to compare pairs of values where one variable (x) is graphed versus another variable (y), usually to determine any correlation.
More about scatter plots
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| sea breeze: |
| Wind that occurs in a coastal area and blows from ocean to land, usually during the day, due to differences in the heating of the land and sea surface. At night the process reverses and a land breeze blows from land to ocean.
Diagrams illustrating sea and land breezes
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| sea level: |
| the average height or elevation of Earth's ocean surface. This height or level defines the zero value of elevation for land masses and ocean depths.
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| sea surface temperature: |
| the temperature of the very top layer of water (or the effective temperature of a thicker layer that includes the top) of Earth's oceans and other large bodies of water. The satellite remote sensing method used determines which sea surface temperature (SST) can be measured. See also the definition for surface temperature.
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| SeaWiFS: |
| the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project. SeaWiFS provides quantitative data on global ocean bio-optical properties. Subtle changes in ocean color represent various types and quantities of marine phytoplankton. The ocean color in the visible light region (wavelengths of 400-700 nm) varies with the concentration of chlorophyll and other plant pigments present in the water. The more phytoplankton present, the greater the concentration of plant pigments and the greener the water. These microscopic marine plants, such as algae and some bacteria, exist at the lowest levels of the food chain and use sunlight or chemical energy, rather than organic material, as sources of energy. It is thought that marine plants remove carbon from the atmosphere at a rate equivalent to terrestrial plants, but knowledge of interannual variability is needed.
The SeaWiFS Project
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| shortwave radiation: |
| Electromagnetic radiation with a wavelength shorter than about 5 microns. Bodies with temperatures in the range of our Sun have a peak energy emission in this wavelength range.
Radiation Explanation
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| slope: |
| the steepness of a line on a coordinate plane, usually defined as the vertical change (rise) over the horizontal change (run) traveling along the line. The slope of a line may be positive or negative, zero or undefined. The image to the right illustrates a positive slope.
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| snow and ice: |
| The amount of snow and ice cover detected on the surface of the Earth from satellite observations. A key challenge to this observation is the detection of clouds, which can look confusingly like snow or ice when viewed from space.
The Cryosphere - Where the World is Frozen
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| snow cover: |
| See snow and ice.
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| snow pit: |
| A hole that is dug into the snow to be able to see all the layers from the ground to the top of the snowpack. This is used to study layers in the snow from different snowfall events, and changes in the snow from any warming (melting) events or other weather conditions that can affect snow cover.
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Image courtesy NASA GSFC |
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| solar collector: |
| a device that captures the Sun's energy and focuses it in a small area as a more usable or storable form. These devices can be simple, such as a greenhouse, or complex like solar panels or solar concentrators.
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| Solar constant: |
| the amount of solar radiation received at the top of the atmosphere on a normal plane at the mean Earth-sun distance; the value is generally accepted to be 1365 Watts per square meter (although this value is still subject to debate).
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| solar declination: |
| the latitude on Earth where the sun is directly overhead at solar noon.
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| solar occultation: |
| A technique of measuring vertical profiles of atmospheric optical depth form Earth orbit using the Sun as a light source..
SAGE III SOLAR
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| solar radiation: |
| the electromagnetic radiation or energy emitted by the Sun. The energy coming from the Sun peaks in visible wavelengths, but also includes ultraviolet and infrared wavelengths.
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| solar zenith angle: |
| the angle between the local zenith (up) and the line of sight to the sun.
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| solstice: |
| the date when solar declination - the latitude on the Earth where the Sun is directly overhead at noon - is +/-23.5 degrees. This occurs twice yearly on June 21 (summer solstice, +23.5 degrees, over Northern Hemisphere) and December 21 (winter solstice, -23.5 degrees, over Southern Hemisphere).
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Image courtesy NOAA |
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| spatial resolution: |
| refers to the horizontal and/or vertical resolution of a data set.
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| SRB: |
| The Surface Radiation Budget Project. SRB data sets contain global averages of surface longwave and shortwave radiative properties, cloud amount, and meteorology using computer models.
The SRB Web Site
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| steradian: |
| a standard unit of solid angle. One steradian is the solid angle made at the center of a sphere by an area on the surface of the sphere equal to the square of the sphere's radius.
Illustration of a steradian
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| stratosphere: |
| the region of the atmosphere located about 10-50km above the surface of the Earth. It contains the benefical ozone layer.
Layers of the atmosphere animation
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Image courtesy NASA |
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| sublimation: |
| the change from solid phase directly to gas phase without passing through a liquid phase. For example, an ice crystal may sublime to water vapor where humidity is low and temperature is below freezing, such as when ice falls from cirrus clouds.
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| sulfur dioxide: |
| A heavy toxic gas that is easily condensed to a colorless liquid and is a major air pollutant. Certain large volcanic eruptions release enough aerosols in the form of sulfur dioxide to noticeably cool the Earth System for several years. Composed of a sulfur atom and two oxygen atoms.
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| surface ozone: |
| a trace gas consisting of three oxygen atoms that is measured at the ground to monitor pollution. Although it is the same ozone as found in the stratospheric ozone layer that beneficially blocks ultraviolet radiation, ozone at the surface is very harmful to humans and plants when its concentration exceeds natural levels. Increases often occur in urban and industrial areas during summer.
Monitoring surface ozone
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| surface temperature: |
| The temperature (may be in degrees F or C, or Kelvin) that is characteristic of the Earth's surface. While we understand this concept since we live on the surface, a little care is needed for remote sensing data. This may refer to the temperature of the air above the surface (what we typically mean by surface temperature and what is in the weather forecast). It can also mean the actual temperature of the surface (think of a black top road on a summer day). For the ocean, it can mean the temperature of the very top layer of water, or the effective temperature of a thicker layer that includes the top. The remote sensing method used determines which temperature can be measured.
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| swath: |
| the portion of Earth's surface or atmosphere measured by an instrument during a single satellite overpass.
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Image courtesy TRMM Science Team |
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