Oceanography

Introduction to Ocean

Three Major Components of the earth include the hydrosphere, the lithosphere, and the atmosphere. Oceans constitute the hydrosphere; the lithosphere is the layer of rocks; the atmosphere is the layer of air. The biosphere encompasses parts of these three layers. It extends several meters into the soil (lithosphere) several hundred meters (over 6 miles) into the atmosphere, and more than 11,000 meters into the ocean. The world’s oceans occupy roughly 71 percent of the earth’s surface. The average depth of ocean is four  km. Oceans are predominant in the Southern Hemisphere, often referred as the marine hemisphere. Landmass, on the other hand, dominates in the northern Hemisphere, which is known as the land hemisphere. The land hemisphere includes the continental masses of Eurasia, North America and Africa above the equator. The marine hemisphere comprises South America, Africa below the equator, Australia, New Zealand, and Antarctica.

The Earth and Ocean basin

Earth
Mass	5.9760 x 1027 grams
Volume	1.083 x 1012 cubic kilometers
Area	510.100 x 106 square kilometers
Equatorial radius	6378.163 kilometers
Polar radius	6356.177 kilometers
Oceans
Volume	1.350 x 109 cubic kilometers
Area	362.033 x 106 square kilometers
Mean depth	3729 kilometers