Key Points

The atmosphere is a mixture of gases, primarily composed of nitrogen and oxygen. It also contains smaller amounts of other gases like carbon dioxide and argon, as well as water vapour and dust particles.

The atmosphere is divided into five main layers based on temperature changes with altitude. From the ground up, they are the Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere.

This is the lowest and most important layer where we live and breathe. Almost all weather phenomena, such as clouds, rain, and fog, occur in the troposphere.

The stratosphere lies above the troposphere and contains the ozone layer. This layer absorbs harmful ultraviolet radiation from the sun, protecting life on Earth.

Meteorites burn up upon entering the mesosphere. The thermosphere is where temperature rises rapidly and auroras occur; it also reflects radio waves back to Earth.

Weather describes the short-term, day-to-day condition of the atmosphere. Climate refers to the average weather conditions of a place over a long period, usually thirty years or more.

The major elements that influence weather and climate are temperature, atmospheric pressure, wind, humidity, and precipitation.

Atmospheric pressure is the weight of air pressing on the Earth's surface. Wind is the movement of air from high-pressure areas to low-pressure areas.

The Indian Meteorological Department (IMD) recognizes four main seasons in India. These are Winter, Summer (pre-monsoon), Monsoon (rainy), and Post-monsoon (retreating monsoon).

The climate of India is strongly influenced by monsoon winds, which are seasonal reversals of wind direction. The word 'monsoon' comes from the Arabic word 'mausim', meaning season.

From June to September, moist winds blow from the sea to the land, bringing widespread rainfall to most of India. This is caused by a low-pressure area forming over the heated landmass.

From October to February, cold and dry winds blow from land to sea. These winds pick up moisture over the Bay of Bengal and cause rainfall on the south-eastern coast, especially in Tamil Nadu.

The monsoon is vital for India's agriculture, economy, and water supply. However, irregular monsoons can cause devastating floods or droughts.

Climate change is the long-term alteration of weather patterns, caused mainly by human activities like burning fossil fuels. This releases greenhouse gases, trapping heat and raising global temperatures.

The effects of climate change include more frequent extreme weather events like floods and droughts, melting glaciers, rising sea levels, and loss of biodiversity.

We can reduce our impact on the climate by taking actions like saving electricity and water, using public transport, recycling, and avoiding single-use plastics.