WEATHER AND CLIMATE

ATMOSPHERE

•The atmosphere is a collection of gases that

makes the Earth habitable.

Composition of the Atmosphere

IMPORTANCE OF ATMOSHPERE

• The atmosphere is an important part of what makes Earth livable. It blocks some of the Sun's dangerous rays from reaching Earth. It traps heat, making Earth a comfortable temperature. And the oxygen within our atmosphere is essential for life.

WEATHER PATTERNS• Because the Earth is round and not flat, the Sun's rays

don't fall evenly on the land and oceans. The Sun shines more directly near the equator bringing these areas more warmth. However, the polar regions are at such an angle to the Sun that they get little or no sunlight during the winter, causing colder temperatures. These differences in temperature create a restless movement of air and water in great swirling currents to distribute heat energy from the Sun across the planet. When air in one region is warmer than the surrounding air, it becomes less dense and begins to rise, drawing more air in underneath. Elsewhere, cooler denser air sinks, pushing air outward to flow along the surface and complete the cycle.

GREENHOUSE EFFECT

STRUCTURE OF THE ATMOSPHERE

TROPOSPHERE

• The layer closest to the Earth• The top of this layer is called “Tropopause”• The gases in the troposphere is essential to

the life on earth.• The temperature decreases with altitude in

troposphere but stops decreasing at tropopause.

• Climatic changes occur here.

STRATOSPHERE

• The second closest layer• The top of stratosphere is called stratopause.• The lower part of stratosphere is cold then it

gets warm at stratopause.• This layer is clear and dry with steady winds so

the jet planes usually fly here.• The ozone layer lies here that absorbs the

ultra violet rays.

OZONE LAYER

Importance of Ozone Layer

• The ozone layer resides in the stratosphere and surrounds the entire Earth. UV-B radiation from the Sun is partially absorbed in this layer. As a result, the amount of UV-B reaching Earth’s surface is greatly reduced. UV-A is other solar radiation are not strongly absorbed by the ozone layer. Human exposure to UV-B increases the risk of skin cancer, cataracts, and a suppressed immune system. UV-B exposure can also damage terrestrial plant life, single cell organisms, and aquatic ecosystems.

MESOSHPERE

• The third closest layer.

• The temperature drops down here.

THERMOSPHERE

• The fourth layer

• The temperature rise again as nitrogen and oxygen atoms absorb solar energy.

IONOSHPERE

• Located from lower mesosphere to top thermosphere.

• Here the air is highly ionized.• Each layer of ionosphere reflects radio waves.• It is the home of Auroras

THE AURORAS• The bright dancing lights of the aurora are

actually collisions between electrically charged particles from the sun that enter the earth's atmosphere. The lights are seen above the magnetic poles of the northern and southern hemispheres. They are known as 'Aurora borealis' in the north and 'Aurora australis' in the south.. Auroral displays appear in many colours although pale green and pink are the most common. Shades of red, yellow, green, blue, and violet have been reported