3. Eide ofere facing terms is used for the circulation of water within the earth's Inydrosphere
Answers
➡️Although Earth's hydrosphere has been around for about 4 billion years,it continues to change in shape.
➡️This is caused by seafloor spreading and continental drift, which rearranges the land and ocean.
➡️It has been estimated that there are 1,386 million cubic kilometres (333,000,000 cubic miles) of water on Earth.
➡️This includes water in liquid and frozen forms in groundwater, oceans, lakes and streams.
➡️Saltwater accounts for 97.5% of this amount, whereas fresh water accounts for only 2.5%.
➡️Of this fresh water, 68.9% is in the form of ice and permanent snow cover in the Arctic, the Antarctic and mountain glaciers; 30.8% is in the form of fresh groundwater; and only 0.3% of the fresh water on Earth is in easily accessible lakes, reservoirs and river systems.
➡️The total mass of Earth's hydrosphere is about 1.4 × 1018 tonnes, which is about 0.023% of Earth's total mass.
➡️At any given time, about 20 × 1012 tonnes of this is in the form of water vapor in the Earth's atmosphere (for practical purposes, 1 cubic meter of water weighs one tonne).
➡️Approximately 71% of Earth's surface, an area of some 361 million square kilometers (139.5 million square miles), is covered by ocean.
➡️The average salinity of Earth's oceans is about 35 grams of salt per kilogram of sea water (3.5%).