EARTH ’S

ATMOSPHERE

The Atmosphere

The atmosphere is a layer of gases surrounding our planet. Each time, the

atmosphere becomes thinner when altitude rises. The layer contains a variety

of gases with a 78% of nitrogen, 21% oxygen, 0.03% carbon dioxide, 0.9%

argon, and other type of gases.

The atmosphere is composed by 5 layers which keeps saved life on Earth by

absorbing ultraviolet rays. It also reduces the warming of the surface and the

temperature.

Composition of the layers of the Earth (lowest to highest):

Troposphere

Stratosphere

Mesosphere

Thermosphere

Exosphere

Troposphere

From the 5 layers of the atmosphere the troposphere is the lowest one.

This layer is habituated by humans. The layer initiates at the Earth's surface

and it goes up to an altitude about 7 to 20 kilometers above the sea level. The

troposphere has a beginning and an end. At the bottom of the troposphere you

will find the boundary layer which is right next to the surface and at the top of

the layer between the troposphere and the stratosphere (the second layer) you

will find the tropopause. In the tropopause everything depends on the season,

weather, latitude, day or night so it basically changes a lot.

In the troposphere, nearby 75 to 80 percent of the mass atmosphere it is

found in this layer as well as almost all of the weather occurs in it. The

troposphere it is heated up from the underneath. This is because the sunlight

warms the ground and oceans and as they get warm they heat up the air that it

is right up of it. The hot air rises up and the troposphere maintains hot. Air on

the bottom of the troposphere is warmest while when it is higher air gets

colder. At the top of the troposphere the temperature of air is about -55° C (-

64° F). Pressure and density of air are less on high altitudes (that’s why it’s

hard to breath) and more in the lowest ones. In the troposphere there are many

clouds and this is because a lot of the water vapor of the atmosphere is in the

troposphere. The wind is unruly in parts as mountains and forests and is much

calmer in places such as beaches or freezing areas.

Stratosphere

The stratosphere is the second layer of the atmosphere. It is right up the

tropopause (the top layer of the troposphere). This layer contains 19.9% of

Earth’s mass and as well has a beginning and an end. It begins right up the

tropopause and its’ top is called the stratopause. The stratosphere is about 50

kilometers of altitude.

The temperature in the stratosphere is totally the opposite of the

troposphere. Here, as altitude rises the temperature gets hotter. This layer is

really dry and there aren’t many clouds since the air contains really poor

quantities of water vapor. But there is an exception; polar stratospheric clouds

are found there. They only appear when they are near the poles in winter.

Polar stratospheric clouds are found on altitudes from about 15 to 25

kilometers and when temperature is below -78°C. Since the air is extremely

thin, airplanes and aircrafts can easily fly in the stratosphere. In the

stratosphere there exist waves carried from the troposphere up to the

stratosphere. These waves carry energy to the stratosphere and from the

stratosphere to the mesosphere.

Mesosphere

The mesosphere is the third layer of the Earth’s atmosphere. This layer

extends starting around 50 to 85 kilometers above the surface. In this layer

temperature reduces when the height increases. As everything, the mesosphere

has a limit too and it varies with latitude and season. Usually the beginning of

the mesosphere is about 50 kilometers and it extends until the mesopause from

about 85 or 100 kilometers. From the entire atmosphere, the mesopause is the

coldest part. Also the mesosphere temperature changes and gets lower when

the altitude starts increasing. This happens because solar heat decreases.

Sometimes, in this layer clouds called “noctilucent clouds” form due to the

high altitudes. These clouds are found much higher than the clouds that we

usually see. As meteors vaporize in the mesosphere, usually this layer contains

their material in huge quantities which are iron and other metal atoms. Also

waves from the troposphere and stratosphere are carried with energy directly

to the mesosphere.

Thermosphere

The thermosphere is the 4th

layer of the atmosphere. It is directly above

the mesosphere and below the exosphere. This layer is around 80 kilometers

above from the surface. Ultraviolet radiation causes ionization in this layer,

and also auroras occurs in it. In the thermosphere temperature increases with

altitude, and the temperature depends on solar activity. Radiation causes that

particles from the atmosphere become electrical charges in this layer.

Temperature in this layer is really high. Even though the temperature is

extremely hot, we will not feel as that hot since it is near vacuum so there is

not sufficient contact with atoms of gas to the transmission of heat. In the

thermosphere the density is very low and molecular interactions are not

frequent so there is not too much transmission of sound.

Exosphere

The exosphere is the last layer of the atmosphere. Here is where atoms

and molecules leak. The exosphere is the limit of the entire atmosphere, it

starts in the end of the thermosphere and then it finishes in the space since is

the last layer. They say that the exosphere is almost like a vacuum since the air

there is really, really thin. The temperature in the exosphere is hot since

particles there move fast. This layer starts approximately 400 miles up.

Life on Earth

Water

Water is suitable for life since it’s a source that besides helping plants

grow and make our world green it maintain us alive. Our body is a big

percentage water and to keep us alive we have to drink it. It also keep us save

from diseases since we can get clean with water and with water we clean

ourselves and many other things.

Oxygen

Many creatures from the troposphere need oxygen to survive. Oxygen is

also important because without oxygen we couldn’t survive since we need

oxygen in our body. Oxygen maintains us alive and combined with water both

are necessary to survive.

Sunlight

The sunlight is really important since it helps grow plant too. To

survive, plants are also necessary. Without plants we couldn’t live because

they give us pure oxygen with the help of the photosynthesis and they need

sunlight and water to grow. So if we do not have sunlight we practically don’t

have plants too.

Altitude, temperature, and pressure

These three elements have a relationship because:

In the troposphere: more altitude = coldest temperature, less pressure

and density

In the stratosphere: more altitude = hotter temperature and less pressure

In the mesosphere: altitude increases = coldest temperature and pressure

In the thermosphere: more altitude = more temperature and pressure

In the exosphere: more altitude = more pressure and temperature

MLA bibliographies

"The Troposphere." The Troposphere. Web. 16 May 2012.

<http://www.windows2universe.org/earth/Atmosphere/troposphere.html>.

"Thermal Structure and Chemical Composition of the Atmosphere." Thermal Structure and

Chemical

Composition of the Atmosphere. Web. 17 May 2012.

<http://www.etap.org/demo/Earth_Science/es8/instruction1tutor.html>.

"(b). The Layered Atmosphere." 7(b) The Layered Atmosphere. Web. 17 May 2012.

<http://www.physicalgeography.net/fundamentals/7b.html>.