Understanding Earth's Atmosphere: Composition, Layers, and Changes

1. Earth Atmosphere Chapter 3 Meteorology \ Dr. Mazin sherzad

2. Earth Atmosphere Chapter 3 1) Composition of the atmosphere 2) Structure of the atmosphere -Principle layers 3) Air Pressure, Density, and Temperature Structure Meteorology \ Dr. Mazin sherzad

3. Atmosphere • The atmosphere is a thin layer of gases that surround the Earth. • The atmosphere protects life on Earth by absorbing ultravioletsolar radiation, warming the surface through heat retention and reducing temperature extremes between day and night. Meteorology \ Dr. Mazin sherzad

4. How did the atmosphere change? • Methane is made up carbon and hydrogen. • Ammonia, is composed of nitrogen and hydrogen. • Sunlight caused chemical reaction among the methane, ammonia and water in the air. • New materials, nitrogen, hydrogen and carbon dioxide, were formed as the methane and ammonia broke down. Methane is an important gas in “global warming” Meteorology \ Dr. Mazin sherzad

5. Solid Particles • Tiny particles of dust, smoke dirt and salt float in the air. • Dust in the air comes from the eruption of volcanoes. • Dirt and smoke comes from people as they burn fuels and drive cars. Meteorology \ Dr. Mazin sherzad

6. Today’s Atmosphere • 600 million years ago the amounts of oxygen and carbon dioxide in the atmosphere began to level off. • Since that time, the composition of the atmosphere has remained fairly constant. Meteorology \ Dr. Mazin sherzad

7. Composition of Atmosphere Meteorology \ Dr. Mazin sherzad

8. Layers of the Atmosphere • The atmosphere is divided into layers according to the major changes in its temperature. Layers with thinner particles can hold less heat. Meteorology \ Dr. Mazin sherzad

9. Air Pressure • The layers of air that surround the Earth are held close to it by the force of gravity. • Because of gravity, the layers of air push down on the Earth’s surface. This is called air pressure. • The upper layers push down on the lower layers so the air pressure near the surface is greater than the air pressure further away. Meteorology \ Dr. Mazin sherzad

10. Structure of the atmosphere Meteorology \ Dr. Mazin sherzad

11. The Troposphere • This is the layer closest to the Earth. • Weather occurs in this layer. Life occurs in the troposphere. • Temperature decreases with height because the troposphere is heated by the surface and not directly by sunlight. • 80% of the atmosphere’s mass This layer contains 99% of the water vapor. Meteorology \ Dr. Mazin sherzad

12. The Stratosphere • The stratosphere extends from the troposphere to an altitude of about 50 km. • temperature increases with height • The ozone layer, which protects against harmful UV radiations, is here. Meteorology \ Dr. Mazin sherzad

13. The Mesosphere • In the mesosphere, 50-90km above the earth, the temperature begins to decrease to –100 degrees C. • The upper region is the coldest. If water vapor is present thin clouds of ice form • Most meteors burn up in this layer • The mesosphere protects the Earth from meteoroids. Meteorology \ Dr. Mazin sherzad

14. The Thermosphere • The air is very thin. The density of the atmosphere and the air pressure are one ten-millionth of what they are at the Earth’s surface. • The temperature is very high in this layer because the rays from the sun are absorbed in this layer. • This layer contains the ionosphere, which causes the reflection of radio waves. Meteorology \ Dr. Mazin sherzad

15. The Exosphere • The upper thermosphere is called the exosphere. • The exosphere extends from 550 km above the surface for thousands of km. The air is very thin. • Artificial satellites orbit in the exosphere. Meteorology \ Dr. Mazin sherzad

16. Temperature in the Layers • The sun is the source of energy for Earth. As the sun’s light passes through the layers some layers contain gases that absorb the energy. • The troposphere is warmed mainly by heat from the ground. • The air temperature decreases 6.5º every kilometer you climb up. Meteorology \ Dr. Mazin sherzad

17. Temperature of Layers Meteorology \ Dr. Mazin sherzad

18. Ozone Layer • Most of the ozone in the atmosphere is found between 16 km and 60 km about the surface of the Earth. • Ozone molecules absorb much of the het and Ultraviolet (UV) rays from the sun.. Meteorology \ Dr. Mazin sherzad

19. Ozone Layer • The oxygen that was left behind joined together, in sets of three, to form a gas known as ozone. • The ozone layer absorbs harmful ultraviolet radiation from space. O2 + hν→ O + O O + O2 + M → O3+ M Meteorology \ Dr. Mazin sherzad

20. Ionosphere • Within the mesosphere and the thermosphere is a layer of electrically charged particles called the Ionosphere. It allows radio waves to travel around the earth. Meteorology \ Dr. Mazin sherzad

21. Hole in the Ozone Layer • The destruction of ozone molecules by CFCs seems to cause a seasonal reduction in ozone over Antarctica called the Ozone hole. Meteorology \ Dr. Mazin sherzad

22. Atmospheric Layers • The layers are identified based on how temperature changes with height • Troposphere – temperature decreases with height • Stratosphere – temperature increases with height • Mesosphere – temperature decreases with height • Thermosphere – temperature increases with height Meteorology \ Dr. Mazin sherzad

23. Layers of the Atmosphere Meteorology \ Dr. Mazin sherzad

24. 3) Air Pressure, Density, and Temperature Structure 4) Atmosphere Hazards