Glossary of Terms

Maybe you've come across a word you don't recognize. Maybe you have heard it before, but you don"t remember what it means. You should be able to find it here. If you can"t find a definition for a term you read on this site, please feel free to email Rose Hayward at rhayward@usgs.gov.

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Albedo
A measure of the reflectivity of light from the surface of Mars. A completely non-reflective (black) surface has an albedo of 0, while a highly-reflective (bright white) surface has an albedo of 1.
Barchan
Dune that is crescent-shaped in plan view with 1 slipface. Barchans result from winds having a single dominant direction in areas with sparse sand supply. They can be gradational with barchanoid and transverse dunes, which form when more sand is available. (McKee, 1979).
Barchanoid
Dune form that consists of connected crescents in plan view with 1 slipface. Barchanoid ridges result from winds having a single dominant direction in areas where sand is more abundant and barchans coalesce. They can be gradational with barchans, which form when sand supply is sparse and transverse dunes, which form when sand supply is most abundant (McKee, 1979).
Equinox
When the sun is closest to the equator. Spring equinox - Ls 0°, Autumn equinox - Ls 180°. See also Solstice.
False Color
Color used to denote a scale (or range) of values at a point.
IR
Infrared light, long wavelength.
Ls
Solar longitude, a measure of where Mars is in its year. Mars, much like Earth, has four seasons. They can be broken into the following groups: 00° to 89° - Spring 90° to 179° - Summer 180° to 269° - Autumn 270° to 359° - Winter.
Solstice
When the sun is furthest from the equator. Summer solstice - Ls 90°, Winter solstice - Ls 270°. See also Equinox.
Transverse Dune
Essentially parallel, straight, asymmetrical ridges with 1 slipface (McKee, 1979). Transverse dunes result from winds having a single dominant direction, oriented with their axes ar right angles to wind direction. They are gradational with barchans and barchanoid dunes.
Vis
Visible light, what you and I can see.