Atmosphere of Earth

Atmosphere of Earth

In this article, we will read about the elements present in the air like- gas pollution, the greenhouse effect, air pressure, moisture, etc.

The atmosphere is an invisible cover of a mixture of different gases that surrounds the Earth up to a certain height. It is an integral and important part of the natural environment.

Its physical conditions keep on changing rapidly due to the incoming Sun’s radiation. The temperature, air pressure, humidity, and other atmospheric conditions keep on changing due to the energy of the Sun.

These changes can also be of a few hours.

Advantages of the Atmosphere

Animals and plants get essential gases from the atmosphere itself which is responsible for the presence of the biosphere on the Earth.

Occurrence of Weather and Climate

The fact of weather and climate occurs only in the atmosphere. They influence the Lithosphere and the Hydrosphere to carry on various processes that keep the circle of life going.

Maintaining a Balance of  Temperature on the Earth

The atmosphere acts like a greenhouse. It allows the sun’s heat to reach the earth by radiating it but saves a large part of the heat radiated by the earth.

That’s why in winter, in the evening or in the first half of the night, the air remains warm for some time even after the earth’s cover has cooled.

Acting Like a Shield on the Earth

Most of the pieces of meteors falling on the earth from space dissolve in the air. In the absence of an

Atmosphere, meteors can hit the Earth’s surface with catastrophic consequences. Therefore, the atmosphere protects the Earth by acting as a shield.

Protection from Ultraviolet Rays

The atmosphere protects us from the sun’s ultraviolet radiation, which comes directly from the sun.

Helpful in Communication

The gases in the upper layers of the atmosphere contain electrically charged particles called ions, which reflect radio waves back to Earth and thus facilitate communication. It is very helpful for radio television etc.

Composition of the Atmosphere

 The atmosphere is a mixture of various gases, dust particles, and steam. It contains 78 percent nitrogen and 21 percent oxygen. 99 percent of it is made up of nitrogen and oxygen.

Other gases, steam and dust particles, etc. make up the remaining percentage of the atmosphere

Amount of gases present in the atmosphere

 Name of gases        Quantity

Nitrogen                     78%

Oxygen                        21%

Organon                    0.94%

Carbon Dioxide       0.03%

Hydrogen                  0.01%

Ozone                  0.000004%

Importance of Gases

All the gases in the atmosphere are very important. Their presence provides protection to the environment.


It helps in the formation of proteins in plants.

The fire remains under control due to its presence, without it or in small amounts, it would not have been possible for humans to control fire.


This is life-giving gas. All living beings breathe through oxygen and keep the life process going.


It protects us from the ultraviolet rays of the sun which are harmful to our skin.


It is essential for plants. It creates a greenhouse effect by preventing the heat of the earth from going out. Water vapor and dust particles are also constituents of our atmosphere, their presence is also useful in some form or the other

Structure of the Atmosphere

The atmosphere made up of layers extends up to a certain height of the earth. Its aerial extent is not known.

Even at an altitude of 1000 km, microscopic amounts of atmospheric gases have been found. The atmosphere can be broadly divided into a structure of five layers


The lowest layer of the atmosphere, near the Earth’s surface, in which air has the greatest density. The whole fact of the weather is in this only. The troposphere extends up to a height of 18 km in the equatorial region while its height is up to 8 km in the polar region.

Being the main part of the atmosphere, it contains a high percentage of oxygen. This is where the facts of weather and climate take place.

Dust particles and water vapor are mostly found here. As we go up in the troposphere the temperature decreases. There is a drop of 1-degree centigrade for every 165 meters of altitude.

Closer to the Earth’s surface, where humans come in contact with it, the troposphere is more important.


The second layer of the earth goes up to a height of 50 km from the surface. Its thickness is greater at the poles and less at the equator.

Most of the ozone gas found in this layer protects us from ultraviolet rays.

The climate is not a factor here. Hence it is an ideal area for air flights. Due to ozone, the temperature decreases with height.


The atmosphere becomes very dense up to an altitude of 50 to 80 km. Here the temperature drops to -100 degree centigrade and the density of gases becomes very less.


It occurs above the mesosphere up to a height of 400 km. of gases at its bottom

Molecules acquire a kind of electric charge and are called ions, due to which it is called the ionosphere. heat to its maximum

reaches 1000 degree centigrade.


This is the outer layer of the atmosphere. The amount of gases in this region is very less and the density is very low. It has no boundaries and eventually merges with interplanetary space.

Air Pollution

Millions of tonnes of waste material are dumped into the atmosphere every year. These are called air pollutants.

These are of two types – solid and gaseous. Dust and bacteria are solid pollutants. Often volcanoes become the main sources of dust pollution.

Human activities, especially in cities, release large amounts of solid pollutants into the atmosphere

The major source of gaseous pollution is the smoke emitted from vehicles which contain carbon monoxide gas.

It is very poisonous. Natural smog and a mixture of substances cause serious health problems.

The low level of ozone is due to air pollution emitted by heavy traffic and industries.

Many rules and regulations have been made to control the source of air pollutants. But to fight this we have to be alert ourselves.

Green House Effect

Land and water get heated by the heat of the sun. After getting heated, both of them radiate the heat towards the atmosphere. This outgoing heat is trapped by carbon dioxide and water vapor.

This trapped heat warms the earth which is called the greenhouse effect. The earth is getting warmer due to many reasons which are called global warming. Today it is one of the most serious environmental problems.

Elements of Weather and Climate


Weather and Climate

The study of weather and its elements is called climatology. The weather changes hourly and daily. The climate is the average weather of a particular place that is characteristic of it.

Temperature, humidity, rain, clouds, sunlight, pressure, and wind are the basic elements of weather and climate. The weather forecast we read on TV, radio, or newspaper

Instruments to Measure Weather


1. Thermometer: It measures the temperature of the environment. With this, the body temperature of the people is also measured.

2. Stevenson’s Screen: It protects the barometer from direct sunlight

3. Six’s Maximum and Minimum: This is the maximum and minimum temperature of the day.

4. Barometer: It measures the pressure of air.

5. Wind Vane: It helps in knowing the direction of the wind.

6. Anemometer: It helps to know the speed of the wind.

7. Rain Gauge: It measures the rate of rainfall.

8. Hyetograph: It provides a continuous record of rainfall.

Temperature is measured in Celsius and Fahrenheit-degrees named after scientists, the Celsius scale is the most common scale for measuring temperature.

This scale is also used in our country, it is a decimal scale in which temperature is measured from 0 to 100 degrees. 10 degrees is the freezing point of water and 100 degrees is the boiling point of water.

Thermometers are always kept in the shade at a height of one meter from the ground. For this a wooden box called a Stevenson screen with slits all around it to allow air to enter freely is used.

Thermography provides a continuous record of the maximum and minimum temperature of temperature over a period of 24 hours.


The pressure exerted by the vertical column of air per unit area is called atmospheric pressure.

Pressure is measured in centimeters or inches of mercury, which is a true measure of the height of the column of mercury. Another unit of pressure is millibar, it is measured by a barometer.

Aneroid Barometer

Nowadays aneroid barometer is used to measure atmospheric pressure. It measures the force exerted by the wind on a metallic plate.

Aneroid barometers are used in altimeters that are fitted in airplanes. An altimeter measures the altitude of the aircraft during flight.

The barograph, which gives a continuous record of pressure, is another instrument that uses an aneroid barometer.


An instrument used to measure wind speed continuously is called an anemograph. Without measurement, one cannot estimate the intensity of the wind.

1. When you find the wind rising straight up, the wind speed is less than km per hour.

2. It is difficult to hold an umbrella when the wind speed is more than 40 km.

3. The wind speed of more than 100 km per hour becomes a storm in which trees fall.


The moisture in the air is in the form of water vapor. Relative humidity is a very common method used in meteorology.

Saturated air has a relative humidity of 100 percent and dry air has 0 percent relative humidity.


Humidity can be measured with the help of an instrument called a hygrometer.

A simple hygrometer consists of two thermometers, moist and dry. The bulb of a thermometer placed in dry air measures the temperature of dry air.

The other bulb of the thermometer is kept moist with the help of threads that measure the temperature of the moist air.

Rain Gauge

It measures the rate of rainfall. It consists of a metallic cylinder, a vessel, and a glass scale with a funnel. The circumference of the funnel is equal to the circumference of the vessel in which the rainwater is collected. Rainwater is collected for 24 hours.

It is measured with a glass scale. The rate of rainfall is measured in millimeters. Snowfall and hail are measured by the amount of water melted. Annual rainfall is generally expressed in centimeters.


The movement of flat moving air over the land from high-pressure areas to low-pressure areas is called wind. The wind is named based on the direction from where it blows.

The wind blowing from the east is called the eastern wind and the wind blowing from the west is called the westerly wind. The direction of the wind is observed with the help of a wind vane.

The arrow of the wind vane indicates the direction of the wind and the direction of the wind is shown on one of the dials of the wind vane. Wind speed is measured with the help of an anemometer.


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