composition and structure of atmosphere · 2019-06-02 · there are different types of gasses in...

COMPOSITION AND STRUCTURE OF ATMOSPHERE

Part I. Chapter 8

WHAT IS ATMOSPHERE ?

Atmosphere is the blanket of the earth

The mixture of different gases that surrounds the Earth all around is called the atmosphere.

The atmosphere is composed of gases, dust particles and water vapor.

The mass of air surrounding the earth up to height of several hundred kilometers

COMPOSITION OF THE ATMOSPHERE

COMPOSITION OF THE ATMOSPHERE

1.Gases

2.Watervapour

3.Dust particles

Atmosphere is mainly composed of three major components.

➢ There are different types of gasses in the atmosphere. Some are permanent gases

➢ The gas that is most abundant is nitrogen followed by Oxygen, Argon and Carbon

➢ Carbon dioxide is meteorologic ally important gas absorbs terrestrial radiation and responsible for Green house effect.

➢ CO2 has been rising due to burning of fossil fuels has also increased the air temperature.

➢ Ozone is the another important components of the atmosphere.

GASES In %

NitrogenOxygenArgon

78200.93

Carbon dioxide

Neon

Helium

Krypton

0.036

0.002

0.0005

0.001

XenonHydrogen

0.000090.00005

1. ATMOSPHERIC GASES

NOAC= Nitrogen Oxygen, Argon & Carbon

2. WATER VAPOUR

It is a variable gas in the atmosphere which decreases with altitude.

It also decreases from the equator towards the poles.

More in warm and wet tropics.

4% of the air by the volume .

It acts like a blanket allowing the earth neither to become too cold nor too hot.

3. DUST PARTICLES

It includes sea salts, fine soil, smoke-soot, ash, pollens, dust and disintegrated particles of meteors.

They are generally concentrated in the lower layers of the atmosphere.

They act as hygroscopic nuclei around which water vapour condenses to produce clouds.

STRUCTURE OF THE ATMOSPHERE

STRUCTURE OF THE ATMOSPHERE

➢ The atmosphere consist of different layers with varying density and temperature.

1. Troposphere.

2. Stratosphere.

3. Mesosphere.

4. Thermosphere.

1. TROPOSPHERE

➢ This is the lower most layer of the atmosphere.

➢ It’s average height is 13 km.

➢ Equatorial regions-18km and Polar regions- 8km.

➢ It contains dust particles and water vapour and 50% of all gases.

➢ This is the most important layer of all biological activity and climatic changes.

➢ The temperature in this layer decreases at the rate of 10C for every 165 m height. The process is called Normal lapse rate.

➢ Tropopause is a transitional zone which separates the troposphere with the stratosphere.

2. STRATOSPHERE

This layer above the tropopause and

extends up to 50 km.

Jet air craft used to fly through this

layer because of watervapour & dust

particles, Air turbulence & clouds are

absent

In this layer temperature increases

with increasing height is known as

inversion of temperature

This layer contains the Ozone layer,

which protects us from harmful

sunlight. Also It act as a shield life on

the earth.

Stratopause which separates

stratosphere and mesosphere

3. MESOSPHERE

➢ This layer is above the stratosphere

➢ It’s elevation ranges from 50 to 80 kms

➢ Density is very low in this layer

➢ Temperature decreasing with the increasing height (Normal Laps Rate)

➢ At 80 km temperature is -1000 C

➢ Mesopause which separates mesosphere and thermosphere.

4. THERMOSPHERE

➢ It’s height ranges from 80 kms

● Temperature can be very high; 4,000F. But no significant heat because density is so low.

➢ Thermosphere is consist of two divisions

a) Ionosphere b) Exosphere

(ionosphere)

➢ It’s height ranges from 80 kms

➢ Temperature increases with increasing height (inversion of temperature)

➢ It contains electrically charged particles known as IONS so called ionosphere.

➢ Radio waves reflected back to earth by this layer help wrks Radio, TV etc.

➢ This is where most small meteorites burn up and is also the location in the atmosphere that the northern lights occur (aurora borealis)

A. IONOSPHERE

B. EXOSPHERE

• This is the highest layer but very little is known about it.

• Whatever contents are there, these are extremely rarefied in this layer and it gradually merges with the outer space.

• Geographers are concerned with the first two layers of the atmosphere.

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