BREATHING COMES NATURALLY
What does the atmosphere do for us? Obviously everyone has to breathe. We need oxygen to keep our bodies working. Just try holding your breath for a few seconds and see what happens. People are not the only ones who need oxygen; all kinds of animals need it too. Without the atmosphere we would all quickly die. But that's not the only thing the atmosphere does for us.
A RADIATION SHIELD
The atmosphere of Earth protects us and all living things on the earth from dangerous radiation from the sun. In addition to the light we see, the sun also gives off ultraviolet radiation. Much of it is filtered out by the atmosphere. Ultraviolet radiation can destroy living cells causing harm to our skin and leading to skin cancer. The sun's rays are important for us. They provide light and heat but they also contain dangerous rays that can harm us. The atmosphere helps to protect us.
SECURITY BLANKET
The atmosphere also keeps us warm. It holds the surface heat on the earth and prevents it from radiating out into space. We call this the greenhouse effect. In a greenhouse people grow plants under the protection of glass or plastic which lets the light come through for the plants to grow, while protecting the plants from cold. In this way people are able to grow plants even in cold weather because the plants stay warm inside the greenhouse. That's the way the atmosphere protects us. Without the greenhouse effect of the atmosphere holding in the heat, the Earth would be a very cold place. That same greenhouse effect also reduces the extreme temperatures between day and night. On the moon, where there is no atmosphere, the daytime temperature can be extremely hot and the nighttime temperature extremely cold. Without the blanket of the atmosphere we might freeze or fry.
WEATHERING THE STORMS
Closely related to temperature regulation, the atmosphere also gives us weather. Wind, rain, and snow depend on the atmosphere. The atmosphere provides cool breezes on a hot day and rain to make the trees and flowers grow. Plants could not grow and animals could not survive without water. Rain provides the water we all need and the atmosphere provides the rain. The air evaporates the water from the oceans and carries it over the land in the form of clouds and then deposits that water where it is needed. The water flows into our streams and rivers and out into the ocean where the cycle is repeated. Without the atmosphere, the water could not reach the farmer's fields to grow our food. Very complex weather patterns including trade-winds and jet streams are part of the atmospheric circulation of the air that distributes heat around the earth. Weather is a function of our atmosphere.
LOOK OUT BELOW!
Another really important thing that the atmosphere does is to protect us from objects coming toward the earth from outer space. Every day meteroids enter the Earth's atmosphere. These are pieces of rock that are traveling through space. When they reach the atmosphere, most of them burn up due to the friction of the air. The ones that don't completely burn up reach the surface of the earth in a much smaller form. When they reach the earth we call them meteorites. The atmosphere protects us from this space junk that would do damage to us, to our homes, and to the earth itself. It is because of the heat created by the friction of the atmosphere that the space shuttle had to be equipped with a heat shield to prevent it from burning up as it re-entered the Earth's atmosphere. That heat caused by friction was dangerous to the astronauts but it is very important to protect us from things coming in from outer space.
PLANT LIFE
The atmosphere is also very important for plants because it contains a small amount of carbon dioxide. Plants use the carbon dioxide (CO2) along with sunshine to carry out a process called photosynthesis. In this process the plants convert the sunlight, carbon dioxide, and nutrients from the ground into energy for them to grow and oxygen for us to breathe. Without enough carbon dioxide in the air, plants can't survive. Also the atmosphere helps plants to grow in another way. Many plants depend on the air to carry pollen from one plant to another in order to create the seeds that are needed to grow new plants. And many of those plants depend on the air to carry the seeds and scatter them around to spread the plants to new areas. Flowers and trees and plants that give us food to eat depend on our atmosphere for their life.
GETTING OFF THE GROUND
Many plants also depend on insects and birds to carry their pollen and their seeds to make it possible for them to reproduce. This leads to another thing which the atmosphere does for us. It makes flight possible. Birds and insects could not fly without the air to support them. Without the air, humans would not be able to fly either. The movements of air over the wing of a bird or an airplane creates an upward lift which makes flight possible. Without the lift provided by the air, an airplane would never get off the ground and neither would a bird or a bee.
LET'S TALK
One more thing the atmosphere does is it allows us to talk to each other. If you were talking to your friend and there were no air between the two of you, your friend would not be able to hear a thing you said. Sound waves depend on the air to carry them from one person to another. When you talk, your vocal cords cause vibration in the air. That vibration is what we call sound. The sounds are shaped by your mouth and they travel to the other person's ear. The other person hears what you said. Without the air between you and that other person you could be moving your lips but the other person wouldn't hear anything coming out of your mouth. The sound of your voice travels to that other person through the air at the speed of about 1100 feet per second. That means if you are far apart it takes a while for the sound to arrive, but it wouldn't get there at all without the air or something else in between to carry the sound. We have all watched movies about space travel where we see a spaceship explode and hear the sound of the explosion. That would not really happen. Because in space there is no air to carry the sound waves. You would be able to see the explosion but you wouldn't hear anything. We need the atmosphere to be able to talk to each other and to hear the birds and the waves and the music around us.
