X TABLE OF CONTENTS 



CHAPTER PAGB 



II. Physical Properties of Sea Water {Con't.) 



Influence of the Altitude of the Sun upon the Extinction 



Coefficients 30 



Cause of the Large Extinction Coefficients in the Sea 30 



The Color of Sea Water 31 



Sea Ice 32 



Freezing and Melting of Ice 32 



Properties of Sea Ice 33 



III. Observations in Physical Oceanography 35 



Oceanographic Expeditions and Vessels 35 



Temperature Observations. 37 



Surface Thermometers 37 



Protected Reversing Thermometers 38 



Unprotected Reversing Thermometers 40 



Thermographs 40 



Water-Sampling Devices 41 



Treatment and Analysis of Serial Observations 43 



Current Measurements 44 



Units and Terms 44 



Drift Methods 44 



Flow Methods 46 



IV. The Heat Budget OF THE Oceans 49 



Radiation 51 



Incoming Radiation; Effect of Clouds; Reflection 51 



Absorption of Radiation Energy in the Sea 54 



Effective Back Radiation from the Sea Surface 58 



The Radiation Budget of the Oceans 60 



Exchange of Heat Between the Atmosphere and the Sea. ... 61 



Evaporation from the Sea 62 



The Process of Evaporation 62 



Observations and Computations of Evaporation 65 



Average Annual Evaporation from the Oceans 67 



Evaporation in Different Latitudes 67 



Annual Variation of Evaporation 68 



Diurnal Variation of Evaporation 69 



V. General Distribution of Salinity, Temperature, and 



Density 71 



Salinity of the Surface Layer 71 



Surface Salinity 71 



Periodic Variations of the Surface SaUnity 73 



Temperature of the Surface Layers 74 



Surface Temperature 74 



Difference Between Air- and Sea-Surface Temperatures .... 75 



Annual Variation of Surface Temperature 77 



Annual Variation of Temperature in the Surface Layers. ... 78 



Diurnal Variation of Surface Temperature 80 



Diurnal Variation of Temperature in the Upper Layers .... 82 



Distribution of Density 82 



Subsurface Distribution of Temperature and Salinity 85 



