The Great Ocean of Air
Did you know that you live at the bottom of an ocean of air? In that ocean, some things live on the bottom, and others swim at different levels above the bottom. We spend most of our time close to the bottom of our ocean of air.
The ocean of air that surrounds the Earth is called the atmosphere (AT-muhs-sfeer). The atmosphere is a mixture of invisible gases. Two gases make up most of the atmosphere: nitrogen (78.08%) and oxygen (20.95%). The remaining 0.97% is made up of 0.93% argon and 0.03% carbon dioxide (the gas you breathe out).
There are many other materials besides the gases in the atmosphere. The amount of these materials varies from place to place and time to time. Water vapor is one of these materials. Air over a desert has almost no water vapor in it. Air over a tropical rain forest, however, may have as much as 4%. Water vapor usually appears as clouds.
The atmosphere has several layers. The bottom layer is called the troposphere (TROP-uhs-sfeer). Most weather occurs in this layer. The second layer is called the stratosphere (STRAT-uhs-sfeer). It contains ozone, which is a special form of oxygen. Ozone keeps the Earth from receiving too much of the Sun's light. The third layer is called the mesosphere (MEZ-uh-sfeer). It helps protect the Earth from meteoroids. As meteoroids burn up in the mesosphere, a streak of light appears. This is what we call a shooting star. The top layer is called the thermosphere (THUR-muh-sfeer). Satellites orbit the Earth in this layer.
The Bible uses the word "heaven" in at least three different ways. The first is the Earth's atmosphere (Matthew 8:20). The second is space, where the Sun, Moon, and stars are (Genesis 15:5). The third heaven is where God is. Paul was once caught up to that "third heaven" (II Corinthians 12:2). Scientists keep learning about the first and second heavens. One day, Christians will live with God in the third heaven.