The Greatest Freshwater System on EarthAstronaut Terry Virts took this photo of the Great Lakes from

The Greatest Freshwater System on EarthAstronaut Terry Virts took this photo of the Great Lakes from the International Space Station. The lakes are one of the most recognizable features of North America from space.The lakes were created by glaciers, which sculpted and changed them over thousands of years. They contain one-fifth of the world’s fresh surface water; enough to submerge the continental US under 3 meters (9.5 feet) of water.The lakes behave, in some ways, like an ocean. They have coastal currents, rip currents (strong, localized, narrow currents that can be dangerous to swimmers), and storm surges. They moderate the temperature of the air around them and affect the amount of precipitation on the nearby land.The lakes are all connected to form one continuous drainage basin. Water starting in Lake Superior will, after as long as 191 years, flow down through St. Marys River into Lake Michigan (retention time 99 years) and Lake Huron (retention time 22 years). Michigan and Huron are technically two halves of one lake. The water leaves Huron through the St. Clair River in the south, connects with Lake St. Clair and then with the Detroit River, which drains into Lake Erie. From there it flows through the Niagara River and over Niagara Falls to get to Lake Ontario. Finally it will flow out through the St. Lawrence River and on to the Atlantic Ocean.Because they are connected, the lakes together make up the greatest freshwater system on the planet. Please note, your own favorite freshwater system is probably “great” as well – the Great Lakes are simply the greatest by volume of freshwater.REPhoto Credit: Terry Virts - NASAhttps://twitter.com/AstroTerryReferences:http://bit.ly/1PvrARQhttp://bit.ly/1F0dkGJ -- source link

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