define the structure of the atmosphere
Answers
Answer:
Explanation:
The atmosphere is made up of different gases, water vapour and dust particles.
The composition of the atmosphere is not static and it changes according to the time and place.
The atmosphere is a mixture of different types of gases.
The atmosphere can be divided into five layers according to the diversity of temperature and density. They are:
Troposphere
Stratosphere
Mesosphere
Thermosphere (Ionosphere)
Exosphere
Troposphere
It is the lowermost layer of the atmosphere.
The height of this layer is about 18 km on the equator and 8 km on the poles.
The thickness of the troposphere is greatest at the equator because heat us transported to great heights by strong convectional currents.
Troposphere contains dust particles and water vapour.
This is the most important layer of the atmosphere because all kinds of weather changes take place only in this layer.
The air never remains static in this layer. Therefore this layer is called ‘changing sphere’ or troposphere.
The environmental temperature decreases with increasing height of the atmosphere. It decreases at the rate of 1 degree Celsius for every 165 m of height. This is called Normal Lapse Rate.
The zone separating troposphere from the stratosphere is known as tropopause.
The air temperature at the tropopause is about – 80 degree Celsius over the equator and about – 45 degree Celsius over the poles. The temperature here is nearly constant, and hence, it is called tropopause.
Stratosphere
Stratosphere is found just above the troposphere.
It extends up to a height of 50 km.
The temperature remains almost the same in the lower part of this layer up to the height of 20 km. After this, the temperature increases slowly with the increase in the height. The temperature increases due to the presence of ozone gas in the upper part of this layer.
Weather related incidents do not take place in this layer. The air blows horizontally here. Therefore this layer is considered ideal for flying of aircraft.
The upper limit of the stratosphere is known as stratopause.
One important feature of stratosphere is that it contains a layer of ozone gas.
The relative thickness of the ozone layer is measured in Dobson Units.
It is mainly found in the lower portion of the stratosphere, from approximately 20 to 30 km above the earth’s surface.
It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere.
It is the region of the stratosphere that absorbs most of the sun’s ultra-violet radiations.
Mesosphere
It is the third layer of the atmosphere spreading over the stratosphere.
It extends up to a height of 80 km.
In this layer, the temperature starts decreasing with increasing altitude and reaches up to – 100 degree Celsius at the height of 80 km.
Meteors or falling stars occur in this layer.
The upper limit of the mesosphere is known as mesopause.
Thermosphere
This layer is located between 80 and 400 km above the mesopause.
It contains electrically charged particles known as ions, and hence, it is known as the ionosphere.
Radio waves transmitted from the earth are reflected back to the earth by this layer and due to this, radio broadcasting has become possible.
The temperature here starts increasing with heights.
Exosphere
The exosphere is the uppermost layer of the atmosphere.
Gases are very sparse in this sphere due to the lack of gravitational force. Therefore, the density of air is very less here.
Answer:
the atmospher has 4 layers: the tropospher that we live in near the surface of the earth; the stratospher that houses the ozone layer; the mesospher that acolder and lower density layer with about 0.1 % of the atmospher ; and the thermospher, the top layer, where the air is hot but very thin
Explanation: