Because salinity (in concert with temperature) affects the density of seawater, it can play a role in its vertical stratification. Essentially, lower salinity water (= lower density) floats on top of higher salinity water (= higher density).
Alternative definition, a choice limited to one of two or more possibilities, as of things, propositions, or courses of action, the selection of which precludes any other possibility: You have the alternative of riding or walking. See more.
An argument is a rationale in which the reason functions as evidence in support of the conclusion. Its purpose is to provide a rational basis for believing the conclusion to be true. An explanation is a rationale in which the conclusion represents an accepted fact and the reason represents a cause of that fact.