The Earth and its Atmosphere

MA. RACHEL B. ESPINOBUHATAN NATIONAL HIGH SCHOOLSorsogon City

The ocean of air around us

The Earth is enveloped in air called the atmosphere. The pull of the Earth keeps this ocean of air close to the Earth.

Without the atmosphere, life cannot exist on Earth, for the atmosphere contains oxygen – the life sustaining gas. From the air, plants get carbon dioxide needed by animals in order to live. The layers of air also protect us from the intense radiation by day and too much loss of heat by night

Layers of the Atmosphere

LAYERS OF THE ATMOSPHERE

Troposphere The bottom layer closest to the

Earth. It extends from the surface upward to a height of 8.16 km. It is the zone of active air currents. Weather occurs in this layer.

Stratosphere The next layer above

the troposphere is the stratosphere. It extends from the top of the troposphere to a height of about 80 km. There the air is much thinner. It is clear and cloudless. This is the layer where jet planes and manned balloons fly.

Mesosphere The layer between 50 km and 80

km above the Earth’s surface is called the mesosphere. Air in this layer is very thin and cold. Meteors or rock fragments burn up in the mesosphere.

Ionosphere It extends from the top of the

stratosphere to a height of about 650,800 km. It is the zone of charged particles called ions. This layer makes the reception of radio waves around the earth possible.

Thermosphere The thermosphere is between 80

km and 110 km above the Earth. Space shuttles fly in this area and it is also where the auroras are found. Auroras are caused when the solar wind strikes gases in the atmosphere above the Poles.

Exosphere The fourth layer is the exosphere. It

begins from the top of the ionosphere and extends upward to about 24,000km. Above this layer is what is commonly known as outer space.

LAYERS OF THE ATMOSPHERE

Air is a Mixture

Air is a mixture of a number of gases. Some are elements and others are compounds. The table below shows the average composition of dry, clean air:

Gas Percent (by volume)

Nitrogen 78.084%Oxygen 20.946%Argon 0.934%

Carbon dioxide 0.033%Other gases 0.003%

Oxygen Supports life. It is the most

important gas for human existence. All animals on Earth breathe in oxygen and use it to oxidize their food. Likewise, we need oxygen to burn fuel in our homes and in factories

Carbon dioxide Carbon dioxide is present in very

small amounts in the atmosphere but it is essential for plant growth. Green plants combine carbon dioxide and water into carbohydrates. Animals and other organisms depend on plants for their food. When food is oxidized in the cells of both plants and animals, CO2 is given off as waste product. It is returned to the air as a product of combustion and decomposition.

Nitrogen Nitrogen which makes four-fifths

of the air cannot be used directly from the air. Lightning and some organisms can fix nitrogen into soluble form. Then it is absorbed by the plants and manufactured into protein foods. It is necessary food element for every plant and animal. It is important constituent of living cells. Nitrogen dilutes oxygen in the atmosphere and therefore lessens the rate at which oxidation or burning may occur.

Other Component of Air WATER VAPOR is an important

component of the atmosphere because (1) it absorbs energy radiated from the earth and therefore helps regulate temperature; (2) the amount of it determines the formation of rainfall clouds and all other forms of precipitation; and, (3) the amount of it affects the bodies’ rate of cooling

The air constantly gets water vapor from the vast surface of the ocean and the smaller bodies of water. Moist land surfaces and the bodies of plants and animals likewise gives off water vapor into the air.

Water vapor is the most variable component of the air. Warm air can hold more water vapor than cold air. There is a higher percentage of water vapor over the sea than over the land. Equitorial air contains more water vapor than polar air.

Another component of air is DUST. Dust particles in the air serve as nuclei for the condensation of water vapor. Dust, therefore, helps to form clouds and rain. Dust also scatters the short blue rays of light and thus makes our skies blue. Air with dust in it is responsible for our beautiful sunrises and sunsets.

The inert gases that make up the atmosphere are also useful in a number of ways. ARGON is used to fill electric light bulbs. NEON is used in lamps because it produces brilliant red glow when subjected to electricity. HELIUM being lighter than air is pumped into balloons to make them go up in the air.

Why is atmosphere important?

1. It serves as a thermal blanket to protect us from heat of the sun’s rays by day while at the same time prevent the escape of heat at night. Without the atmosphere, the temperature would be excessively high in the day and unbearably low at night.

2. It shields us from falling meteors.

3. The atmosphere is responsible for weather conditions. Winds, clouds, rain and other kinds of precipitation are formed in the atmosphere.

4. It makes blue skies, red sunsets and bright-colored rainbows possible.

5. It serves as a medium for transmitting sound. Sound waves travel through the air.

6. It bounces radio waves back to Earth. This helps us enjoy radio and television and exchange wireless messages with persons in various parts of the globe.

7. The buoyant force exerted by air enables birds and aircraft to fly.

8. Moving air drives sailboats and windmills, distributes clouds and rainfall in wide areas and creates waves and currents in the sea.

9. Moving air wears down rocks, erodes soil and deposits sand dunes.

10. The atmosphere shields us from excessive amounts of ultraviolet rays of the sun.

QUIZ

Write the letter of the correct answer on your answer sheet.

1. PAGASA forecasts bad weather. Which layer of the atmosphere is responsible for it?

a. Stratosphereb. Tropospherec. Ionosphered. Exosphere

2. Plants give off this gas during photosynthesis. What is this gas?

a. Carbon dioxideb. Oxygen c. Argon d. Helium

3. Why is water vapor important?a. It is responsible for blue skies and

red sunsetsb. It absorbs energy radiated from

the earthc. It is used to fill electric lightsd. It is used by plants in

photosynthesis

4. We can receive radio broadcasts from great distances because they are returned back to Earth by the _____.

a. Troposphereb. Exospherec. Ionosphered. Stratosphere

5. What is the importance of nitrogen?

a. Plants convert it into protein foodb. It is used to burn fuelc. It serves as a condensation

nucleusd. It is responsible for blue skies

6. Which gas do green plants make into food?

a. Argonb. Heliumc. Carbon dioxided. Oxygen

7. Burning will not occur if there is a lack of ____.

a. Carbon dioxideb. Hydrogenc. Heliumd. Oxygen

8. Dust particles in the air are important because they ____.

a. Serve as nuclei for condensationb. Help form cloud particlesc. Cover the opening of leavesd. Are made into food by green

plants

9. Which of the following diseases will get worse if the patient inhales polluted air?

a. Hepatitisb. Bronchitisc. Tonsilitisd. Gastritis

10. Which component of the air is responsible for blue skies and red sunsets?

a. Water vaporb. Carbon monoxidec. Carbon dioxided. Dust

ANSWERS:

1. PAGASA forecasts bad weather. Which layer of the atmosphere is responsible for it?

a. Stratosphereb. Tropospherec. Ionosphered. Exosphere

2. Plants give off this gas during photosynthesis. What is this gas?

a. Carbon dioxideb. Oxygen c. Argon d. Helium

3. Why is water vapor important?a. It is responsible for blue skies and

red sunsetsb. It absorbs energy radiated from

the earthc. It is used to fill electric lightsd. It is used by plants in

photosynthesis

4. We can receive radio broadcasts from great distances because they are returned back to Earth by the _____.

a. Troposphereb. Exospherec. Ionosphered. Stratosphere

5. What is the importance of nitrogen?

a. Plants convert it into protein foodb. It is used to burn fuelc. It serves as a condensation

nucleusd. It is responsible for blue skies

6. Which gas do green plants make into food?

a. Argonb. Heliumc. Carbon dioxided. Oxygen

7. Burning will not occur if there is a lack of ____.

a. Carbon dioxideb. Hydrogenc. Heliumd. Oxygen

8. Dust particles in the air are important because they ____.

a. Serve as nuclei for condensationb. Help form cloud particlesc. Cover the opening of leavesd. Are made into food by green

plants

9. What gas is most abundant in our atmosphere?

a. Carbon dioxideb. Oxygenc. Neond. Nitrogen

10. Which component of the air is responsible for blue skies and red sunsets?

a. Water vaporb. Carbon monoxidec. Carbon dioxided. Dust

Suggested Video: National Geographic Our

Atmosphere Earth Science (shows deeper understanding about the Earth’s atmosphere.) Duration: 50:28

http://youtu.be/5Tz8oyuT4E0