Question #9363c
1 Answer
The gases released from the earth and carried in by comets that formed our current atmosphere were rich in water.
Explanation:
A typical comet contains about 1015 kilograms of water -- enough to entirely fill the Great Lakes.
Because the earth was very hot, the water in Earth's newly developed atmosphere was water vapor. Then, as the earth cooled, the water vapor in the atmosphere condensed and fell as torrential rains.
At first, Earth's surface was still so hot that the water quickly vaporized and returned to the atmosphere. But as Earth cooled further, the water remained on its surface longer and longer as a liquid.
Eventually, Earth's oceans and lakes filled with water that only returned to the atmosphere by evaporation due to the Sun, as it does today. When the atmosphere had cooled enough for some of the water vapor in the atmosphere to condense as snow or ice crystals and fall to Earth's surface, glaciers and ice caps formed.
As water continues to work its way to the surface or is carried in by comets, the hydrosphere may gradually increase in volume until, in a few billion years, it covers Earth's entire surface.
