Revision: Atmosphere Geography ICSE ICSE Class 7 CISCE

The envelope of air around the Earth is called the atmosphere. It is composed of nitrogen, oxygen, water vapour, and carbon dioxide, with other gases present in small quantities. The atmosphere is like a protective blanket that keeps our planet safe and helps support life. 

The topmost layer of the atmosphere is called the Exosphere.

Atmosphere is a thin blanket of air that surrounds the earth. It protects us from the harmful rays of the sun. It consists of several gases in which nitrogen and oxygen occupy the major portion.

These are chloro-fluoro carbons and are used as propellants in aerosol cans, refrigerants in refrigerators, air conditioning and as solvent cleaners in the microelectronic industry.

The layer of the atmosphere which extends to a height of 80 km above the stratosphere is called Mesosphere.

The ionosphere, which extends from 80 km to 480 km is known as the Thermosphere.

The envelope of air around the Earth is called the atmosphere. It is composed of nitrogen, oxygen, water vapour, and carbon dioxide, with other gases present in small quantities. The atmosphere is like a protective blanket that keeps our planet safe and helps support life. 

The heating-up of the earth’s atmosphere due to trapped infrared rays reflected from the earth's surface by atmospheric gases is called the greenhouse effect.

• The greenhouse effect is a naturally occurring phenomenon that heats Earth's surface. Without it, Earth's temperature would be -18°C instead of 15°C.
• Greenhouse gases are transparent to solar radiation but retain and reflect back long-wave heat radiation. Main gases — CO₂ (60%), CH₄ (20%), CFCs (14%), N₂O (6%).
• Earth's surface re-emits heat as infrared radiation. Greenhouse gases like CO₂ and CH₄ absorb this and return heat to Earth's surface — causing the greenhouse effect.
• Rising CO₂ due to the burning of fossil fuels and deforestation intensifies the greenhouse effect, causing global warming.
• Global warming leads to melting of polar ice, rising sea levels, changes in rainfall patterns and loss of biodiversity.