• Nitrogen- is the most abundant gas in the atmosphere.
• Nitrogen is crucial for the survival of plants.
• Oxygen- stands second in terms of abundance in the atmosphere.
• Humans and animals breathe in oxygen from the atmosphere.
• Carbon dioxide- is another key gas in the atmosphere.
• Green plants utilize carbon dioxide for photosynthesis and in turn release oxygen.
• Argon

The atmosphere is divided into five layers starting from the earth’s surface.

• Troposphere- the layer closest to the earth. It has an average height of 13 km. The air we breathe exists in this layer. It is also the layer where most weather phenomena occur.
• Stratosphere- situated above the troposphere, it extends up to a height of 50 km. This layer is free from weather phenomena and is ideal for flying aeroplanes. It contains the ozone layer.
• Mesosphere- the third layer of the atmosphere. It lies above the stratosphere and extends up to a height of 80 km.
• Thermosphere -The temperature rises rapidly with height in the thermosphere. The ionosphere is a part of this layer and extends between 80-400 km. This layer is crucial for radio communications.
• Exosphere- The final and uppermost layer of the atmosphere.

• Weather refers to the daily conditions of the atmosphere.
• Climate represents the average weather conditions of a place over a long period.
• Temperature is a measure of the hotness or coldness of the air.
• Air Pressure is the pressure exerted by the weight of air on the earth’s surface.
• Wind refers to the movement of air from high-pressure areas to low-pressure areas.
• Winds can be broadly categorized into three types
  • Permanent winds – These winds, such as trade winds, easterlies and westerlies, blow consistently in a particular direction throughout the year.
  • Seasonal winds – These winds change their direction in different seasons. For example, the monsoon winds in India.
  • Local winds – These winds blow during a certain period of the day or year in a small area. For example, the land and sea breezes or the local hot and dry wind in the northern plains of India, called loo.