the four spheres

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The Four Spheres
Tatum Digirolamo
Geography 103-02
For centuries, humans have been exploring and have discovered that everything in Earth's system can be placed into one of four major classifications: land, water, living things, or air. These four categories are actually called "spheres." There is the lithosphere, which is the land, hydrosphere for the water, atmosphere meaning the air, and lastly, the biosphere, which is life. These four spheres are all dependent on each other making our entire world connect.

Life’s most significant source is water, which is why it takes up most of earth’s percentage. This leads us to the hydrosphere. The Earth’s hydrosphere contains all of the solid, liquid, and gaseous water of our planet. This includes oceans, lakes, glaciers, and moisture in the air. Ninety-seven percent of Earth’s water are the oceans, and the remaining three percent is fresh water. The thickness ranges from ten to twenty kilometers and the hydrosphere was formed in conjunction with the atmosphere.

Our atmosphere is the body of air that surrounds our planet. Most of the atmosphere is dense because majority of it is positioned close to the earth’s surface. The air of our atmosphere is contained of seventy-nine percent nitrogen and twenty-one percent of oxygen. The atmosphere is responsible for the weather, which occurs in the lower atmosphere. It is also separated into numerous layers of air; from inner to outer layers they are troposphere, stratosphere, mesosphere, and thermosphere. The troposphere is where the weather occurs. Stratosphere is essentially cloud free and is above the troposphere. The mesosphere is the coldest of all and forms clouds of ice. Lastly, there is the thermosphere. This is where temperatures decrease and increase rapidly due to the thin air. Also many satellites surround the thermosphere.

The lithosphere evolved about 4.6 billion years ago. It is composed of an outer most layer of hard rock, which is...