They occur where sedimentation proceeds slowly or where currents sort the deposits. The salinity of the surface waters in the open ocean ranges from 33 to 37 parts per thousand and varies with latitude and season. Although the minimum salinity values are found just north of the equator, in general the lowest values are in the high latitudes and along coasts where large rivers flow into the ocean. Maximum salinity values occur at about 25 deg north latitude. Surface salinity values are influenced by evaporation, precipitation, river inflow, and melting of sea ice.
Maximum temperatures occur north of the equator, and minimum values are found in the polar regions.
The Atlantic Ocean consists of four major water masses. The North and South Atlantic central waters constitute the surface waters. The tides are a general wave that moves from south to north. In latitudes above 40 deg north some east-west oscillation occurs. The climate of the Atlantic Ocean and adjacent land areas is influenced by the temperatures of the surface waters and water currents as well as the winds blowing across the waters.