COMPOSITION OF AIR
Nitrogen (78%) – It is the most abundant gas in the atmosphere and is essential for plant
growth. Plants absorb nitrogen in the form of compounds from the soil, which helps in their
development.
Oxygen (21%) – Oxygen is necessary for the survival of humans and animals as they need it
for respiration. It also supports combustion, which means it is required for burning fuels like
wood and petrol.
Carbon Dioxide & Other Gases (1%) – Carbon dioxide (CO₂) is present in small amounts but
is crucial for plants as they use it for photosynthesis. Other gases, such as argon, neon,
helium, and hydrogen, are present in trace amounts and do not play a major role in daily life.
Water Vapour & Dust Particles – The amount of water vapour in the air varies and plays a
significant role in weather patterns, such as rainfall and humidity. Dust and smoke are also
present in the air, affecting air quality and sometimes causing pollution.
Air is essential for all living beings on Earth as it provides oxygen for respiration, which is necessary
for survival. It also contains nitrogen, which helps plants grow by enriching the soil. Carbon dioxide in
the air is crucial for plants as they use it in photosynthesis to produce food and release oxygen.
Water vapour present in the air plays a vital role in weather patterns, influencing rainfall and
humidity. Air also helps in dispersing seeds, controlling temperature, and enabling flight for birds and
aircraft. However, pollution from industries and vehicles is degrading air quality, making it important
to protect and preserve clean air for a healthy environment.
STRUCTURE OF ATMOSPHERE
The atmosphere is divided into five main layers based on temperature variations and altitude. These
layers play a crucial role in supporting life and regulating Earth's climate.
1. Troposphere (0-13 km)
o The lowest layer where all weather phenomena like rain, storms, and clouds occur.
o Contains about 75% of the total atmospheric gases.
o Temperature decreases with altitude (about 6.5°C per km).
o Essential for life as it has oxygen for respiration.
2. Stratosphere (13-50 km)
o Contains the ozone layer, which protects Earth from harmful UV rays.
o Almost free from weather disturbances, making it ideal for jet aircraft flights.
o Temperature increases with altitude due to ozone absorption of solar radiation.
3. Mesosphere (50-80 km)
o The coldest layer of the atmosphere, where temperatures drop to -90°C.
, o Protects Earth from meteoroids, as they burn up due to friction before reaching the
surface.
4. Thermosphere (80-400 km)
o Also called the ionosphere, it contains electrically charged particles (ions).
o Helps in radio communication by reflecting radio waves to Earth.
o Temperature increases with height, reaching 1,500°C or more.
5. Exosphere (Above 400 km)
o The outermost layer gradually merges into space.
o Composed mainly of light gases like hydrogen and helium.
o Satellites orbit in this layer due to its extremely low air density.
WEATHER AND CLIMATE
Weather:
Weather refers to the day-to-day atmospheric conditions of a place, including temperature,
humidity, rainfall, wind speed, and air pressure. It changes frequently and can vary within hours or
days.
Climate:
Climate is the average weather pattern of a place over a long time (usually 30 years or
more). It includes long-term trends in temperature, rainfall, wind, and other atmospheric
conditions.
Temperature:
Temperature is the measure of how hot or cold a place or object is, usually expressed in
degrees Celsius (°C) or Fahrenheit (°F). It is an important factor in weather and climate.
Insolation:
Insolation refers to the amount of solar radiation (sunlight) received by the Earth's surface in
a given time. It affects temperature and climate patterns.
Nitrogen (78%) – It is the most abundant gas in the atmosphere and is essential for plant
growth. Plants absorb nitrogen in the form of compounds from the soil, which helps in their
development.
Oxygen (21%) – Oxygen is necessary for the survival of humans and animals as they need it
for respiration. It also supports combustion, which means it is required for burning fuels like
wood and petrol.
Carbon Dioxide & Other Gases (1%) – Carbon dioxide (CO₂) is present in small amounts but
is crucial for plants as they use it for photosynthesis. Other gases, such as argon, neon,
helium, and hydrogen, are present in trace amounts and do not play a major role in daily life.
Water Vapour & Dust Particles – The amount of water vapour in the air varies and plays a
significant role in weather patterns, such as rainfall and humidity. Dust and smoke are also
present in the air, affecting air quality and sometimes causing pollution.
Air is essential for all living beings on Earth as it provides oxygen for respiration, which is necessary
for survival. It also contains nitrogen, which helps plants grow by enriching the soil. Carbon dioxide in
the air is crucial for plants as they use it in photosynthesis to produce food and release oxygen.
Water vapour present in the air plays a vital role in weather patterns, influencing rainfall and
humidity. Air also helps in dispersing seeds, controlling temperature, and enabling flight for birds and
aircraft. However, pollution from industries and vehicles is degrading air quality, making it important
to protect and preserve clean air for a healthy environment.
STRUCTURE OF ATMOSPHERE
The atmosphere is divided into five main layers based on temperature variations and altitude. These
layers play a crucial role in supporting life and regulating Earth's climate.
1. Troposphere (0-13 km)
o The lowest layer where all weather phenomena like rain, storms, and clouds occur.
o Contains about 75% of the total atmospheric gases.
o Temperature decreases with altitude (about 6.5°C per km).
o Essential for life as it has oxygen for respiration.
2. Stratosphere (13-50 km)
o Contains the ozone layer, which protects Earth from harmful UV rays.
o Almost free from weather disturbances, making it ideal for jet aircraft flights.
o Temperature increases with altitude due to ozone absorption of solar radiation.
3. Mesosphere (50-80 km)
o The coldest layer of the atmosphere, where temperatures drop to -90°C.
, o Protects Earth from meteoroids, as they burn up due to friction before reaching the
surface.
4. Thermosphere (80-400 km)
o Also called the ionosphere, it contains electrically charged particles (ions).
o Helps in radio communication by reflecting radio waves to Earth.
o Temperature increases with height, reaching 1,500°C or more.
5. Exosphere (Above 400 km)
o The outermost layer gradually merges into space.
o Composed mainly of light gases like hydrogen and helium.
o Satellites orbit in this layer due to its extremely low air density.
WEATHER AND CLIMATE
Weather:
Weather refers to the day-to-day atmospheric conditions of a place, including temperature,
humidity, rainfall, wind speed, and air pressure. It changes frequently and can vary within hours or
days.
Climate:
Climate is the average weather pattern of a place over a long time (usually 30 years or
more). It includes long-term trends in temperature, rainfall, wind, and other atmospheric
conditions.
Temperature:
Temperature is the measure of how hot or cold a place or object is, usually expressed in
degrees Celsius (°C) or Fahrenheit (°F). It is an important factor in weather and climate.
Insolation:
Insolation refers to the amount of solar radiation (sunlight) received by the Earth's surface in
a given time. It affects temperature and climate patterns.
