ATMOSPHERE

our atmosphere ....

The earth is surrounded by a layer of gas called the

atmosphere. This thin blanket of air is an integral

and important aspect of the planet. It provides us with

the air we breathe and protects us from the harmful

effects of sun’s rays.

The atmosphere extends up to a height of about

1,600 kilometres. The atmosphere is divided into five

layers based on composition, temperature and other

properties. These layers starting from earth’s surface

are called the troposphere, the stratosphere, the

mesosphere, the thermosphere and the exosphere.

The atmosphere is composed mainly of nitrogen and

oxygen, which make up about 99 per cent of clean,

dry air. Nitrogen 78 per cent, oxygen 21 per cent and

other gases like carbondioxide, argon and others

comprise 1 per cent by volume. Oxygen is the breath

of life while nitrogen helps in the growth of living

organisms. Carbon dioxide, though present in minute

amount, is important as it absorbs heat radiated by

the earth, thereby keeping the planet warm. It is also

essential for the growth of plants.

The density of the atmosphere varies with height. It

is maximum at the sea level and

decreases rapidly as we go up. 

You

know, the climbers experience

problems in breathing due to this

decrease in the density of air. They

have to carry with them oxygen

cylinders to be able to breathe at

high altitudes. The temperature also

decreases as we go upwards. The

atmosphere exerts pressure on the

earth. This varies from place to place.

Some areas experience high pressure

and some areas low pressure. Air

moves from high pressure to low pressure. Moving air

 is known as wind.

There are five primary layers of the atmosphere, namely the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Let's take a closer look at each of these layers:

Troposphere: The troposphere is the layer closest to the Earth's surface, extending from the ground up to about 7-20 kilometers (4-12 miles) in altitude, depending on the latitude and season. This is where weather occurs and where most of the Earth's atmospheric gases are concentrated. The temperature in the troposphere generally decreases with increasing altitude, at a rate of about 6.5 degrees Celsius per kilometer.

Stratosphere: The stratosphere is the layer above the troposphere and extends from about 20 to 50 kilometers (12-31 miles) in altitude. This layer contains the ozone layer, which absorbs most of the Sun's harmful ultraviolet radiation. Unlike the troposphere, the temperature in the stratosphere generally increases with altitude due to the absorption of solar radiation by the ozone layer.

Mesosphere: The mesosphere is the layer above the stratosphere and extends from about 50 to 85 kilometers (31-53 miles) in altitude. In this layer, the temperature once again decreases with altitude. The mesosphere is also the layer where most meteoroids burn up upon entering the Earth's atmosphere, creating bright streaks of light known as meteors or shooting stars.

Thermosphere: The thermosphere is the layer above the mesosphere and extends from about 85 kilometers (53 miles) to the edge of space, around 600 kilometers (373 miles) in altitude. The temperature in the thermosphere can reach as high as 2,500 degrees Celsius (4,532 degrees Fahrenheit) due to the absorption of extreme ultraviolet radiation from the Sun. The thermosphere also contains the ionosphere, a region of charged particles that reflects radio waves back to Earth, allowing for long-distance communication.

Exosphere: The exosphere is the outermost layer of the Earth's atmosphere, extending from the top of the thermosphere to the edge of space, around 10,000 kilometers (6,214 miles) in altitude. This layer is extremely thin, with a very low density of gases, and gradually merges with the vacuum of outer space. Satellites and other spacecraft orbit in the exosphere, where they are largely unaffected by the Earth's atmosphere.

Overall, the layers of the Earth's atmosphere play a crucial role in regulating the climate and protecting life on our planet by absorbing harmful radiation, providing breathable air, and allowing for long-distance communication and space exploration.