772 



TABLES 885-899.— OCEANOGRAPHY * 



TABLE 885.— SOME DATA ON THE EARTH AND ITS SURFACE 



Part 1. — Dimensions 



The earth is a great oblate spheroid with the oceans making up about 71 percent of the 

 area. The dimensions of the earth are as follows : 



Equatorial radius 6378.388 km 



Polar radius 6356.912 km 



Area of surface 510,100,934 km 2 



Volume of geoid 1,083,319,780,000 km 8 



The surface consists of : 



Oceans and seas 361.059X10" km 2 or 70.8 percent 



Land 148.892X 10" km 2 or 29.2 percent 



The land surface is of various elevations above sea level, the mean being about 840 m, 

 while the average depth of the three great oceans and adjacent seas is about 3800 m (Table 

 886). The highest elevation and the lowest elevation in each continent are given in Part 2. 



Part 2. — Area and elevation of continents 



Area 

 10" km2 



Africa 29 8 



North America .... 21.5 



South America .... 17.6 



Asia 44.0 



Europe 9.7 



Australia 7.7 



TABLE 886.— SEA -WAVE HEIGHT IN FEET FOR VARIOUS WIND VELOCITIES 



AND DURATIONS 



Waves consistently higher than the values given are not found because stronger winds 

 blow the tops of the waves off. Isolated waves up to 80 feet are due to the addition of two 

 or more crests. 



One of the longest swell periods recorded was 23 seconds. According to the relations 

 given, its length in deep water would equal 2,650 feet, and its velocity 69 knots. A 28-second 

 swell has been recorded near Cape of Good Hope. Its length must have been almost 

 three-quarters of a mile and its speed 84 knots. 



TABLE 887.— APPROXIMATE HEIGHT OF SWELL IN FEET AT VARIOUS 

 DISTANCES FROM THE STORM AREA 



Distance from storm area in nautical miles 



* Tables 888 to 894, and 897 prepared by R. H. Fleming, U. S. Hydrographic Office. 

 SMITHSONIAN PHYSICAL TABLES 



