तुम से मिलने थी आई!!!
T S M The I E (Troposphere, Stratosphere, Mesosphere, Thermosphere, Ionosphere Exosphere)
Our Inner-consciousness says…
TruSt Me In The Exam
Tr – Troposphere
St – Stratosphere
Me – Mesosphere
In – Ionosphere
The earth is surrounded by the atmosphere, which is the body of air or gasses that protects our planet and enables life. Most of our atmosphere is located close to the earth’s surface where it is most dense. The air of our planet is 78% nitrogen and just under 21% oxygen; the small amount remaining is composed of carbon dioxide and other gasses.
The earth’s atmosphere consists of few layers like spherical shells. On the basis of the characteristics of temperature and air pressure, there are five layers from the earth’s surface upwards.
1) Troposphere: It is the lower most and the most important layer of the atmosphere as almost all the weather phenomena like fog, cloud, dew, frost, rainfall, hailstorm, cloud-thunder, lightning etc. occur in this layer. In this layer, temperature decreases with increasing height at the rate of 10 C/165 m or 6.5 0C/1000m. This rate of decrease in temperature is called Normal lapse rate. The average height of the troposphere is about 16 km over the equator and 6 km over the poles.
2) Stratosphere: The upper limit of the stratosphere is taken to be 50km. Temperature remains stable at the beginning of this layer but it suddenly starts changing after the height of 20 km. This sudden change in temperature is due to the presence of Ozone Layer, which absorb the ultraviolet radiations. This layer of the atmosphere is almost free from the weather disturbances, hence it is preferred by the pilots to fly their aeroplanes.
3) Mesosphere: This layer extends between 50 km and 80 km. Temperature again decreases with increasing height. At the uppermost limit of mesosphere (80km) temperature becomes -80degree C. This limit is called Mesopause above which temperature increases with increasing height. The part of the atmosphere beyond Mesopause is known as Thermosphere where temperature increases rapidly with increasing height. Thermosphere is divided into two layers viz. Ionosphere and Exosphere.
4) Ionosphere: It extends from 80 km to 640 km. electrically charged or ionized particles are abundantly found in this layer. There are number of ionic layers in this sphere which reflect back the radio waves of low, medium, high and very high frequency.
5) Exosphere: It represents the upper most layers of the atmosphere. It extends beyond 640 km of height from the sea level. Electrically charged particles are found abundantly in this layer also. The atmosphere becomes rarefied at the height of 1000 km and it ultimately merges with the space beyond that height.
In most of the one-day exams one question on these layers usually come to irritate us. So learn them conceptually, having diagram of atmosphere in the mind.
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