Atmosphere.pptx
- 1. Atmosphere
- 2. What is the Atmosphere? The atmosphere is the blanket of gases which surrounds Earth. It is held near the surface of the planet by Earth's gravitational attraction.
- 3. Without the atmosphere there could be no life on Earth. The atmosphere: • contains the air we breathe; • protects life from harmful radiation from the Sun; • helps keep the planet's heat from the Sun from escaping back into space; • is a major element of the water cycle; • keeps the climate on Earth moderate compared to that of other planets.
- 4. • The atmosphere is made up of a mixture of gases, mostly nitrogen, oxygen, argon and carbon dioxide. • It reaches over 500km above the surface of the planet. • There is no exact boundary between the atmosphere and outer space. • Atmospheric gases become thinner the higher up you go. • The atmosphere just keeps getting less and less dense, until it "blends" into outer space.
- 5. The atmosphere is divided into four layers based on temperature: • the troposphere, • stratosphere, • mesosphere, and • thermosphere.
- 7. • This is the lowest layer of the atmosphere, closest to the surface of the earth. • The troposphere varies in height in different parts of the world, from about 8km above sea level at the poles, to 16km at the equator. • Within the troposphere, the temperature drops rapidly the higher you go. • This is the layer where we see clouds and most of the "weather" occurs. • The top layer of the troposphere is called the tropopause. • Within the troposphere the temperature drops to a low of - 56ºC. This marks the beginning of the tropopause. • Through the tropopause, the temperature reverses and begins to increase. • The height of the tropopause varies from the poles to the equator, but also from the summer to winter.
- 9. • For a distance of about 18km above the tropopause, there is a layer called the stratosphere. • In this layer, the pressure continues to decrease, but the temperature increases gradually to 0ºC. • Like the troposphere, the stratosphere also varies in thickness. • It is quite deep over the poles and thinner over the equator. • The stratosphere contains a layer of ozone which absorbs the Sun's ultraviolet rays, protecting life on the earth's surface. • The top layer of the stratosphere is called the stratopause. In this layer the temperature, once again, begins to fall.
- 10. The Mesosphere
- 11. • The mesosphere reaches up to about 80km above the surface of the earth. • This is the coldest layer of the atmosphere, where the temperature drops rapidly with altitude. • In the top layer of the mesosphere, called the mesopause, the temperature bottoms out at a low of about -100ºC at 80km above the earth. • After that the temperature begins to rise again with greater altitude. • This is the layer where meteorites usually burn up as they enter the atmosphere.
- 12. The Thermosphere
- 13. • The thermosphere extends upwards from a point 80-100 kilometres above the earth's surface. • There is very little air in this layer. • The temperature continues to rise in the thermosphere and beyond, increasing for an indefinite distance into space.
- 14. The Exosphere • The exosphere is the very outer limit of the atmosphere. • The bottom of this layer is found at 500 kilometres above the Earth's surface. • The pressure drops to little more than a vacuum. Auroras form in the exosphere. Auroras- उषा
- 15. Thank You