of Baltimore and Philadelphia showed equally high correlations between 
mean air temperature and surface water temperature whenthe mean air 
temperature data were taken at the same location as the surface water 
temperature data. Local temperature data from climatic summaries of 
the Weather Bureau or similar sources should be used for inland air 
temperature data because landward extension of isotherms from marine 
atlases do not reflect the land-sea thermal discontinuity. 
In areas where cold currents, warm currents, or upwelling are 
persistent, the water temperature modifies air temperatures so that 
climatic air temperature data reflect these phenomena. These factors 
do not cause anomalies from the general case; however, high tidal ranges 
and fresh water river discharge are phenomena which do present 
anomalies in air-water temperature differences from the general case 
of low turbulence and homogeneous salinity. It is very possible that 
upwelling and thermal current advection may cause anomalous situations 
from the general vertical thermal structure. However, in this 
preliminary system development, it is deemed impractical to use 
upwelling and thermal advection currents in the classification system. 
CLASSIFICATION SYSTEM 
By using the CLASSIFICATION INDEX which follows, it is possible 
to classify any harbor in the world according to the following criteria: 
(a) Mean air temperature in the warmest and coldest months, 
(b) An index of continentality as determined by the annual range of 
mean monthly air temperature, 
(c) Tidal range, and 
(d) Presence or absence of fresh water discharge. 
Turbulence influenced by winds and waves, the volume of river 
discharge, the bottom slope, the depth of water, and other minor 
influences probably cause some anomalies from the general case of 
low turbulence and homogeneous salinity. Such environmental influences 
were considered too trivial or impractical to incorporate into a general 
system of classification. Upwelling and horizontal thermal advection 
currents are presumed to be reflected in the mean air temperature for 
any location and are not regarded as classification items. 
