[Geography Notes] on Stratosphere and Mesosphere Pdf for Exam

The atmosphere can be defined as the gas and the aerosol envelope which extends from the ocean land, and from the ice-covered surface of a planet to space above. The atmosphere density goes on to decrease outward, this happens because of the gravitational attraction of the earth, which pulls the gases and aerosols inward. 

In this context, we will learn about different layers of the atmosphere viz. Stratosphere, Mesosphere, Troposphere, Thermosphere. 

Stratosphere and Mesosphere

The stratosphere is typically a layer of the earth’s atmosphere. Moving upward, this will be the second layer of the atmosphere. The bottom of the stratosphere is round about 10 km above the ground situated at the middle latitudes. The top portion of the stratosphere occurs at an altitude of about 50 km. While the height of the bottom of the stratosphere keeps varying with altitude and seasons. The lower boundary of the stratosphere is known as tropopause while the upper boundary is called the stratopause.

The mesosphere is another layer of the Earth’s atmosphere. The mesosphere is right above the stratosphere and below the thermosphere layer. This layer extends from about 50 to 85 km above our planet’s earth.

The temperature gradually decreases with the height in the mesosphere. The coldest temperatures in Earth’s atmosphere are found near the region of the top of this layer. At the bottom of the mesosphere is the stratopause lies the boundary between the mesosphere and the stratosphere. 

The mesosphere is quite difficult to study, so lesser-known facts are available about this layer of the atmosphere than other layers. Weather balloons or other aircraft fail to fly high enough to reach this layer, the mesosphere. Satellites orbit above this layer cannot directly measure their traits. 

Troposphere

The troposphere is the lowermost layer of the Earth’s atmosphere and this layer is the site of all the weather occurrences on Earth. The tropopause is the boundary on the top of this layer, this separates the troposphere from the stratosphere.

75 percent of the atmosphere’s mass comes under this layer. On average, the weight of the molecules present in the air is around 14.7 lb and this covers most of the atmosphere’s water vapor. The most dominating gases are nitrogen which is 78 percent and oxygen that is 21 percent, with the remaining 1% as argon and traces of hydrogen ozone (that is formed of oxygen), with other constituents. 

Thermosphere

The thermosphere is a layer of the atmosphere that is directly related to the mesosphere and down below the exosphere. This extends from about 90 km (that is 56 miles) to between 500 and 1,000 km (which is 311 to 621 miles) above our planet.

Temperatures rise sharply in the lower thermosphere which is below 200 to 300 km altitude, then level off and hold fairly steady with the increasing altitude above that height. Here the solar activity gets strongly influenced by temperature in the thermosphere. The thermosphere is typical of about 200° C which is hotter in the daytime than at night, and this is roughly 500° C hotter at the time when the Sun is very active than at other times. 

Distance of Stratosphere, Ionosphere, Troposphere, and Mesosphere

Troposphere

The troposphere starts right at the Earth’s surface which extends 8 to 14.5 kilometers higher (which is 5 to 9 miles). The troposphere is the densest layer of the atmosphere. All-weather types are in this region.

Stratosphere

The stratosphere here starts just above the troposphere which extends up to 50 kilometers that is 31 miles high. This ozone layer functions by absorbing and scattering the solar ultraviolet radiation is in this layer.

Mesosphere

The mesosphere starts immediately above the stratosphere and this extends to 85 kilometers (which is 53 miles) high. Meteors in the space burn up in this layer.

Thermosphere

The thermosphere here starts right above the mesosphere and this extends to 600 kilometers (that is 372 miles) high. The Aurora and satellites occur in this definite layer.