Introduction
- The atmosphere provides us with oxygen and carbon dioxide for plants.
- It is a protective layer covering the Earth, protecting the Earth's surface from harmful rays of the Sun and the harsh environment of space.
- The atmosphere is a mixture of various gases, water vapor and dust particles, which extends to great heights above the Earth's surface.
- It is divided into different layers, each of which has its own characteristics and functions.
Composition of the atmosphere
1. Gases
2. Water vapour
3. Dust particles
1. Gases
- Oxygen (21%): Essential gas for humans, animals and most organisms.
- Nitrogen (78%): The most abundant gas, which provides essential nutrients for plants.
- Carbon dioxide (0.03%): Necessary for plants in the process of photosynthesis, and a major cause of the greenhouse effect. This gas absorbs the sun's radiation and helps keep the Earth warm.
- Ozone (O₃): This gas found in the stratosphere of the atmosphere absorbs the sun's ultraviolet rays, protecting the Earth's surface from harmful radiation.
- Other gases: Gases such as helium, hydrogen, argon, and krypton are also found.
2. Water vapour
- The amount of water vapor present in the atmosphere varies with time and place.
- It decreases with altitude.
- Water vapor balances the earth's temperature.
- It absorbs the sun's radiation and stores the heat emanating from the Earth, preventing the Earth from cooling down.
- Water vapor causes clouds, fog, dew, and precipitation, which change the Earth's weather.
3. Dust particles
- Dust particles enter the atmosphere from a variety of sources, such as sea salt, soil, pollen, smoke, ash, and broken particles of meteors.
- Convective air currents can carry dust particles to higher altitudes. Dust particles are more prevalent in the lower atmosphere, but they can also reach higher altitudes.
- Dust particles help condense water vapor, which leads to the formation of clouds. Dust particles scatter sunlight, causing the sky to appear blue.
STRUCTURE OF ATMOSPHERE
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Ionosphere
5. Exosphere
1. Troposphere
- 8-18 km from the earth's surface.
- It is the lowest and most important layer of the atmosphere, where all life activities and weather phenomena take place.
- For every 165 metres of height the temperature decreases by 1°C.
- In this layer the temperature decreases with height.
- Water vapor, dust particles and clouds are found in it.
- Here within the layer there are weather changes like rain, storms, winds etc.
2. Stratosphere
- Up to an altitude of 18-50 km.
- The ozone layer is found in the stratosphere, which protects the Earth's surface from harmful sun radiation by absorbing ultraviolet rays.
- The temperature in this layer increases with altitude, as the ozone layer absorbs the sun's radiation.
- There are no weather changes in this layer and jet streams are also found here, which flow at high speed at high altitude.
3. Mesosphere
- Up to a height of 50-80 km.
- This is the coldest layer of the atmosphere, where temperatures can drop to -100°C.
- In this layer the meteors burn and break up before reaching the Earth.
- In this layer the temperature decreases with height.
- Above this layer lies the mesopause, where the temperature is the lowest.
4. Ionosphere
- Up to an altitude of 80–400 km.
- This layer contains ionized particles, which reflect radio waves and return them back to the Earth.
- This layer is important for radio communications.
- In this layer the temperature increases with altitude.
- Due to the electrically charged particles present here, Auroras are visible on the North and South Poles.
5. Exosphere
