Sleet 



(1) In the United States, frozen or partly frozen raindrops 

 in the form of particles of clear ice. (2) In British use, snow 

 and rain falling together. 



Slick (Slick Spot) 



A small area of Alkali or Solonetz (q. v.) soil. 



Slime Mold 



An organism in the phylum Myxomycophyta, character- 

 ized in part by a naked, fluid mass of protoplasm that can 

 move with a flowing motion, cf. Wasting disease. 



Slip 



The downhill movement for a short distance of a mass 

 of wet or saturated soil. 



Slope 



The inclination of the surface of the land from the hori- 

 zontal. Level 0-3.0 (0-5%), gentle 3.0-8.5 (5-15%), moderate 

 8.5-16.5 (15-30%), steep 16.5-26.5 (30-50%), very steep 

 26.5-45 (50-100%), precipitous above 45 (over 100%). 



Slough 



A wet depression with deep mud. cf . Swamp, Marsh, Bog. 



Sludge 



Muddy, ooze-like sediments in a river bed, tidal flat, or 

 similar location. 



Smog 



A polluted atmosphere in which products of combustion 

 such as hydrocarbons, soot, sulfur compounds, etc., occur in 

 detrimental concentrations for human beings and other 

 organisms, especially during foggy weather. 



Snow Density 



The water content of snow expressed as a percentage by 

 volume. In snow surveys, the ratio of the scale reading 

 (inches of water) to the length of the core of snow in inches. 



315 



