The Atmosphere
The atmosphere surrounds Earth and protects us by blocking out dangerous rays from the sun. The atmosphere is a mixture of gases that becomes thinner until it gradually reaches space. It is composed of Nitrogen (78%), Oxygen (21%), and other gases (1%).
Oxygen is essential to life because it allows us to breathe. In addition, some of the oxygen has changed over time forming ozone. The ozone layer filters out the sun's harmful ultraviolet radiation. Recently, there have been many studies on the ozone layer connected to the greenhouse effect . Scientists believe that the greenhouse effect is increasing the earth's temperature by trapping the sun's energy.
The atmosphere is divided into five layers depending on how temperature changes with height. Most of the weather occurs in the first layer. It is thickest near the surface and thins out with height until it eventually merges with space.
1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer. The troposphere is the lowest layer of the Earth's atmosphere. The air is very well mixed and the temperature decreases with altitude. Air in the troposphere is heated from the ground up. The surface of the Earth absorbs energy and heats up faster than the air does. The heat is spread through the troposphere because the air is slightly unstable.
2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun. In the Earth's stratosphere, the temperature increases with altitude. On Earth, ozone causes the increasing temperature in the stratosphere. Ozone is concentrated around an altitude of 25 kilometers. The ozone molecules absorb dangerous kinds of sunlight, which heats the air around them. The stratosphere is located above the top of the the troposphere.
3) Meteors or rock fragments burn up in the mesosphere. In the Earth's mesosphere, the air is relatively mixed together and the temperature decreases with altitude. The atmosphere reaches its coldest temperature of around -90°C in the mesosphere. This is also the layer in which a lot of meteors burn up while entering the Earth's atmosphere. The mesosphere is on top of the stratosphere
4) The thermosphere is a layer with
auroras. It is also where the space shuttle orbits. The
thermosphere is the fourth layer of the Earth's atmosphere and is located above
the mesosphere. The air is really thin in the thermosphere. A small change in
energy can cause a large change in temperature. That's why the temperature is
very sensitive to solar activity. When the sun is active, the thermosphere can
heat up to 1,500°C or higher! The Earth's thermosphere also includes the region
of the atmosphere called the ionosphere. The ionosphere is a region of the
atmosphere that is filled with charged particles. The high temperatures in the
thermosphere can cause molecules to ionize. This is why an ionosphere and
thermosphere can overlap.
5) The atmosphere merges into space in the extremely thin exosphere.
This is the upper limit of our atmosphere.
Very high up, the Earth's atmosphere becomes very thin. The
region where atoms and molecules escape into space is referred to as the
exosphere. The exosphere is on top of the thermosphere.
Answer the following:
1 The atmosphere is divided into how many layers?
2 Which part of the atmosphere would you expect an aircraft to fly?
3 Which layer of the atmosphere does the space shuttle orbit the earth?