Understanding Earth's Atmosphere Layers and Heat Transfer

1. Atmosphere Module 2 Lesson 3 Notes

2. Gases in the Atmosphere By Life of Riley (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

3. Layers of the Atmosphere Image from: http://www.universetoday.com/14367/planet-earth/

4. Basis for Layers • Layers are based on TEMPERATURE CHANGE within the layer. • As you move up through the troposphere, temperature decreases. • As you move up through stratosphere, temperature increases. • As you move up through the mesosphere, temperature decreases • As you move up through the thermosphere, temperature increases.

5. Image: [Public domain], via Wikimedia Commons

6. Characteristics of Layers • Troposphere: contains convection currents created by the sun’s heat which cause most of our weather • Stratosphere: contains the ozone layer • prevents some ultraviolet radiation UV light from reaching Earth’s surface, also where airplanes fly • Mesosphere:meteors burn up when they hit this layer • Thermosphere: divided into Ionosphere and Exosphere. Satellites & radio waves travel in this layer. This is the hottest layer

7. Thermosphere has 2 parts: • Ionosphere: • Lower thermosphere • Contains electrically charged particles due to absorption of ultraviolet radiation and X-rays that are given off by the sun • Aurora Borealis can be seen in this layer • Radio waves travel easily in this layer • Exosphere: • Upper thermosphere • Air is extremely thin • Satellites travel here because there is very little friction with air.

8. Aurora Borealis • It is a glow in the night sky produced in the upper atmosphere by ionized particles from the solar wind interacting with Earth’s magnetic field. By M.Buschmann (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

9. Transfer of Heat Heat can move in three ways: • 1- Conduction: heat is transferred through direct contact. • 2- Convection: heat is transferred by a hot fluid (gas or liquid) circulating or moving. • 3- Radiation: heat is transferred by electromagnetic waves.

10. Conduction • If a metal rod is left in the fire long enough, eventually the end we are holding will become too hot for us to handle. • Heat was transferred from the flames in the fire to the metal rod, and then from molecule to molecule in the rod until it reaches our fingers via conduction.. http://swtechfire.com/fundamentals-of-fire-engineering/

11. What is Convection?  Density differences in temperatures cause heat to rise and cool to sink, this applies to gasses and liquids Examples: • Heated water becomes less dense and rises, boiling water • Hot air expands and is less dense hot air balloon Image from: https://upload.wikimedia.org/wikipedia/commons/0/08/Convection.gif

12. Radiation • Imagine standing in front of a camp fire and holding out your hands in front of you…what do you feel? • Warmth as your hands absorb the radiation coming from the fire. Image from: http://www.ck12.org/physical-science/Thermal-Radiation-in-Physical-Science/lesson/Thermal-Radiation-MS-PS/

13. Heat moves throughout (within) our atmosphere in CONVECTION CURRENTS Public Domain: https://commons.wikimedia.org/wiki/File%3AEarth_Global_Circulation.jpg

14. Hadley Cell and the Intertropical Convergence Zone https://sisgeographyigcsewiki.wikispaces.com/atmosphere,+weather+and+climate

15. By Kaidor [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

16. Albedo • Indicates how well a surface reflects solar energy. Image from: https://rgreenbergscience.wikispaces.com/SCIENCE+IMAGES

17. Climate vs. Weather • Weather – the current state of the atmosphere • Short-terms variations in atmosphere • Climate – the long term variations in weather for a particular area • Usually averaged over the course of 30 years of more

18. Adiabatic Cooling and Heating • Adiabatic Cooling - is the process of reducing heat through a change in air pressure caused by volume expansion. • Adiabatic Heating – process that increases heat through increase in pressure. Image from: https://is2104.files.wordpress.com/2010/02/orographic-lift-jpg2.jpeg

19. Latent Heat Release • Latent heat is the energy absorbed by or released from a substance during a phase change from a gas to a liquid or a solid or vice versa. • Latent heat plays a very important role in thunderstorms and hurricanes. • Thunderstorms release enormous amounts of latent heat which adds to the instability in the atmosphere causing some thunderstorms to become severe. • On a day with a lot of water vapor in the air (high humidity) the potential for latent heat release makes it more likely for convective showers and thunderstorms to develop.

20. Why do we have seasons? • The Earth’s axis is tilted at 23.5 degrees, which changes the angle at which the Sun’s rays hit the Earth’s surface. Image from AstronomyOnline.org

21. Seasons • When the North Pole tilts away from the Sun, the angle of the Sun’s rays falling on the Northern Hemisphere is low. • This means the Northern Hemisphere experiences fewer daylight hours, less energy, and lower temperatures. • The opposite occurs in the Southern Hemisphere during this time: more Sun rays and warmer temperatures. Public domain: https://commons.wikimedia.org/wiki/File:Seasons.svg

22. Equinox • Equal amounts of light and dark • Equinox – the Sun’s rays strike Earth at a 90 degree angle along the equator. The hours of daylight and darkness are approximately equal everywhere on Earth that day. • Autumnal Equinox – occurs on September 22 or 23 • Marks the beginning of fall in the Northern Hemisphere • Vernal Equinox – occurs on March 21 or 22 • Marks the beginning of spring in the Northern Hemisphere

23. Solstice • The point at which the Sun is as far north or as far south of the equator as possible. • Summer Solstice – occurs on June 21 or 22; marks the beginning of summer in the Northern Hemisphere • Winter Solstice – occurs on December 21 or 22; marks the beginning of winter in the Northern Hemisphere