Composition and Structure of Atmosphere
The Atmosphere is the mixture of different gases that surrounds the Earth like a blanket. It is absolutely essential for life. While we can survive for some time without food or water, we cannot live for more than a few minutes without breathing the air from the atmosphere. It provides life-giving gases like oxygen for humans and animals, and carbon dioxide for plants.
The atmosphere is an integral part of the Earth's mass. About 99 percent of its total mass is found within 32 km of the Earth's surface. The air itself is colourless and odourless; we can only feel its presence when it moves as wind.
The atmosphere is made up of three main components: gases, water vapour, and dust particles. The mix of these components changes as you move higher up from the Earth's surface.
The atmosphere is a mixture of many gases. However, the proportion of these gases is not uniform at all heights.
Two of the most significant gases from a meteorological standpoint are Carbon dioxide and Ozone.
Carbon dioxide (CO2): This gas is crucial for the green house effect. It is transparent to the sun's incoming radiation, allowing sunlight to pass through and warm the Earth. However, it is opaque to the outgoing heat (terrestrial radiation) from the Earth's surface. It absorbs this heat and reflects some of it back, which keeps the planet warm.
Ozone (O3): Found between 10 and 50 km above the Earth's surface, ozone acts as a protective filter. It absorbs harmful ultra-violet (UV) rays from the sun, preventing them from reaching the surface and harming life.
Water vapour is a variable gas, meaning its amount changes depending on location and altitude.
The atmosphere contains various small solid particles from different sources. These include:
Dust particles are mostly concentrated in the lower layers of the atmosphere, but strong air currents can carry them to great heights. Their concentration is higher in subtropical and temperate regions due to dry winds, compared to the equatorial and polar regions.
The atmosphere is not a single, uniform layer. It is divided into five different layers based on temperature and density. The density of the atmosphere is highest near the surface and decreases as you go higher.
The main components of the atmosphere that change and influence human life are known as the elements of weather and climate. These are:
The atmosphere is the mixture of different gases that surrounds the Earth like an envelope. It is essential for all life, providing oxygen for animals and humans, and carbon dioxide for plants. While we can survive for some time without food or water, we cannot live for more than a few minutes without breathing air. This shows how crucial the atmosphere is.
The air that makes up our atmosphere is colourless and odourless, and we can only feel it when it moves as wind. About 99 percent of the total mass of the atmosphere is found within 32 km of the Earth's surface.
The atmosphere is made up of three main components: gases, water vapour, and dust particles. The mix of these components changes as you go higher. For example, oxygen becomes almost negligible at a height of 120 km, while carbon dioxide and water vapour are found only up to 90 km from the Earth's surface.
Gases are the primary component of the atmosphere. While the volume of most gases is constant, some, like carbon dioxide, are changing.
Water vapour is a variable gas, meaning its amount changes depending on location and altitude.
The atmosphere contains many small solid particles from various sources. These include:
These dust particles are usually concentrated in the lower layers of the atmosphere but can be carried to great heights by air currents. Their concentration is higher in subtropical and temperate regions due to dry winds.
The atmosphere is not uniform; it is divided into five different layers based on temperature and density. The density of the atmosphere is highest near the Earth's surface and decreases as altitude increases.
The troposphere is the lowermost layer of the atmosphere and is the most important for all biological activity.
The zone that separates the troposphere from the next layer is called the tropopause. Here, the temperature is nearly constant, reaching about -80°C over the equator and -45°C over the poles.
Found directly above the tropopause, the stratosphere extends up to a height of 50 km.
The mesosphere lies above the stratosphere and extends up to a height of 80 km.
The thermosphere is the layer above the mesosphere. Within this layer is a region known as the ionosphere.
The exosphere is the uppermost layer of the atmosphere.
The main elements of the atmosphere that are constantly changing and influence human life are:
These elements combine to create the weather we experience daily and the long-term climate of a region.
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