Significance of Atmosphere

The atmosphere is an insulating blanket protecting the Earth. It softens the intense light and heat of the Sun. Its Ozone layer absorbs the most deleterious wavelengths of the Sun's ultraviolet rays and thus protects living organisms from extinction.

The atmosphere is bound to the earth by gravity. Satellites like the moon, who have very low gravitational power, cannot and do not hold an atmosphere.

The earth presents a hospitable environment for life, almost solely because of its atmosphere. Many plants reproduce by pollen carried by winds. Birds can fly only because of the air, and the water cycle of the earth is maintained through the atmosphere.

The atmosphere diffuses sunlight as well, giving blue skies and the reds, pinks, oranges, and purples of sunrise and sunset.

Density & Temperature

The atmosphere extends as far as 9600 km above the earth's surface. The density of the atmosphere varies with height. It is maximum at the sea level and decreases rapidly as we go up. 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.

Atmospheric Pressure

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.

Composition of Atmosphere

The atmosphere is composed mainly of nitrogen and oxygen, which make up about 99% of clean, dry air. About 78% of the atmosphere's volume is made up of nitrogen, and nearly 21% consists of oxygen. Other gases like carbon dioxide (0.03%), argon (0.93%) and others (0.04%) comprise 1% by volume. Apart from these gases, tiny dust particles are also present in the air.