The Atmosphere

1. The Atmosphere Weather DynamicsScience 10 Source: Nelson Science 10 Text 13.4 ~ Page 510 Approx. 30 minutes Presentation Time Image from: http://csep10.phys.utk.edu/astr161/lect/earth/weather.html

2. Atmosphere • Consult diagram on page 511 • It surrounds us (wind, the sky, when you take a breath) • “is the blanket of air and moisture that surrounds Earth” (Nelson Science 10 510). • Most dense at sea level, less dense higher in the atmosphere • At approx. 500km above the surface of the earth, there are very few molecules left and space begins. • (510)

3. Layers . . . • Altitude: “the height above sea level, usually measured in metres (m) or kilometres (km). (Altitude can also be called elevation.)” (Nelson Science 10 510). • Are thickest at the equator • Air is warmer above the equator and expands = takes up more room • Air at the poles is colder and takes up less room. • (Nelson 510)

4. Astronomy 161 - http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html

5. Troposphere: • Closest to earth’s surface • Up to 16 km at equator (8km at poles) • Contains most of the moisture • Responsible for our weather patterns • Temperature decreases as altitude increases • (Nelson 510) • Troposphere Images • http://en.wikipedia.org/wiki/Earth's_atmosphere • http://www.mardiros.net/atmosphere/troposphere.html

6. Tropopause • Temperature rises because of ozone (absorbs energy from the sun) • Temperature difference keeps layers separated • (Nelson 511)

7. Stratosphere: • Dry layer • 12-50 km • Highest concentrations of ozone • This ozone layer helps to protect the earth from harmful uv rays. • Temperature of this layer increases with altitude. • ** Ozone near the ground in not helpful like it is in the upper atmosphere. • (Nelson Science 10 511) • Stratosphere • http://www.mardiros.net/atmosphere/stratosphere.html

8. Mesosphere • Middle layer • 50-80 km • Low temperature • Low density of gases • All parts of the atmosphere up to this point (except for water vapour and ozone concentrations) are fairly similar in make up. • (Nelson Science 10 511) • Mesosphere: • http://www.mardiros.net/atmosphere/mesosphere.html

9. Thermosphere (Ionosphere) • 80-500 km • Low density • Molecules have more energy = higher temperature • X-rays are absorbed in this layer (part of the reason the temperature is higher) • Ionosphere: higher energy radiation from the sun causes particles to become electrically charged • i.e. Auroras (Northern/Southern Lights) • (Nelson Science 10 511)

10. Examples of Auroras • Auroras: the Northern and Southern Lights http://csep10.phys.utk.edu/astr161/lect/earth/aurora.html Southern Lights (Aurora Australis) – Taken from the Space Shuttle Endeavour

11. Website Examples of Auroras • Michigan Tech – Aurora Page • http://www.geo.mtu.edu/weather/aurora/ • Auroras – The Northern and Southern Lights • http://csep10.phys.utk.edu/astr161/lect/earth/aurora.html

12. Exosphere • “thin outermost layer of the atmosphere” (Nelson Science 10 511). • Up to 800km above the surface of the earth. (Wikipedia Atmosphere). • There are a few hydrogen particles widely spaced apart. • Can be considered “space” • Nelson Science 10 511 • Exosphere: • http://www.mardiros.net/atmosphere/exosphere.html

13. Temperature Gradient • “the change of temperature over a distance” (Nelson Science 10 511). • For example, in the troposphere the temperature decrease -6 C for every 1000m. • Other layers are less consistent • Nelson Science 10 511

14. Supporting Life • The atmosphere provides: • Oxygen & Nitrogen = support life • Carbon dioxide = needed by plants for photosynthesis • Ozone absorbs UV radiation • Part of the water cycle • Protection from meteorites (burn up in the atmosphere because of the friction) • Helps keep the average temperature in a range that can support life. • Water vapour and carbon dioxide trap heat energy from the ground • Circulates air to maintain an energy balance • (Nelson Science 10 511-512)

15. Atmospheric Pressure • “the pressure the air exerts as gravity pulls it toward the centre of Earth” (Nelson Science 10 512). • Highest at sea level = particles closest together • Higher altitudes = less pressure • Depends on other factors i.e. if air is rising or falling. • Pressure Gradient: • “a measure of the amount the atmospheric pressure changes across a set distance. Pressure gradients can be vertical or horizontal” (Nelson Science 10 512). • Nelson Science 10 512

16. Refer to page 512 to examine ways of representing atmospheric pressure. • Kilopascals (kPa) 1kPa = 1000 Pa • Measured by a barometer • Scientists use ballons with a radiosonde (has electronic sensors (temp, press, water vap) info is sent back to earth using radio signals.) • Nelson Science 10 512-513

17. Websites to View: • Astronomy 161 The Solar System • http://csep10.phys.utk.edu/astr161/lect/index.html

18. Heat Transfer . . . revisited • Consider the following: • Only 30% of the earth’s surface is land • Clouds often cover much of the surface • Most solar energy interactions occur with water • “Lakes, rivers and oceans absorb 93% of incoming solar radiation that reaches their surfaces” (Science Power 10 427). (Science Power 10 427)

19. Specific Heat Capacity • “the amount of heat that is required to raise the temperature of 1 gram of a substance 1 degree Celcius” (Science Power 10 427). • Large specific heat capacity = smaller temperature increase • “water increases much less than the temperature of most similar substances after absorbing the same amount of energy” (Science Power 10 428). • Examples of Specific Heat Capacity (J/g C): • Pure water 4.18 • Dry air 1.00 • Brick 0.84 • Science Power 10 427-428

20. Text Questions: • Page 513 # 5, 6, 7