1. Monday, 8/30/20101 ATMO 1300-006 Class #2 Monday, August 30, 2010 Chapter 1 Introduction to the Atmosphere

2. Weather Weather is the condition of the atmosphere at a particular location and moment. These atmospheric conditions include, among others, temperature, relative humidity, dew point, pressure, wind speed and direction, cloud cover, and precipitation. What causes weather? Ultimately, the sun Monday, 8/30/20102

3. Definitions Meteorology is the study of weather variables—temperature, humidity, pressure, wind speed and direction, cloud cover, precipitation, the processes that cause weather, and the interaction of the atmosphere with the Earth’s surface, ocean, and life. Monday, 8/30/20103

4. Climate The climate of a region is the condition of the atmosphere over many years. Described by long-term averages of atmospheric conditions such as temperature and precipitation. Includes extremes as well as averages Climatology is the study of climate. Monday, 8/30/20104

5. Meteorology and Atmospheric Science Usually used interchangeably Atmospheric science includes not only meteorology but some other topics as well –Charged particles and electricity in the ionosphere, parts of the upper atmosphere –Atmospheres of other planets –Includes the study and simulation of climate –Includes the study of climate change Monday, 8/30/20105

6. What is the atmosphere? A fluid A thin layer surrounding the Earth Mainly a mixture of invisible gas with some solid and liquid particles that stays in place on account of the force of gravity Monday, 8/30/20106

7. 7 What’s in the atmosphere? Invisible gases –Some are permanent gases, some variable –Some are abundant, some not (trace gases) –Some are greenhouse gases, some not –Some pollutants, some not Liquids –Water: cloud droplets, raindrops, haze, fog –Pollutants Solids –Water: ice crystals in clouds, snow –Soil, sand, acid, pollen, other substances

8. Monday, 8/30/20108 Abundance of gases in the atmosphere

9. Monday, 8/30/20109 Gases in the atmosphere Nitrogen: most abundant (78%), not very reactive, permanent, not a greenhouse gas, emitted from volcanoes Oxygen (O 2 : 2 nd most abundant (21%), essential for combustion, respiration, a greenhouse gas only in the stratosphere and above (not near the surface), permanent, comes from plants as a product of photosynthesis

10. Monday, 8/30/201010 Other gases in the atmosphere Argon (1%), permanent, not reactive Water vapor, highly variable (0-4%), extremely important to the weather and essential to life, most abundant of the greenhouse gases, comes from volcanoes and maybe comets, hugely important to climate, invisible, makes air lighter –Part of a cycle called the hydrologic cycle –Has a whole chapter, Chapter 4

11. Monday, 8/30/201011 The Hydrologic Cycle: sources and sinks

12. On average, more than 50% of the globe is covered with clouds Monday, 8/30/201012

13. Monday, 8/30/201013 Still another gas in the atmosphere Carbon dioxide, the 2 nd most abundant greenhouse gas, variable with concentrations increasing every year and higher now than ever before in Earth’s history, important for climate change and global warming –Has a cycle of sources and sinks called the Carbon Dioxide (CO 2 ) Cycle

14. Monday, 8/30/201014 Carbon dioxide measurements at Mauna Loa, Hawaii

15. Monday, 8/30/201015 The carbon dioxide cycle: Sources and sinks

16. Monday, 8/30/201016 Another gas: Methane –Is another important greenhouse gas –Concentrations are increasing –Comes from human activities, including the cultivation of rice, burning of forests, coal mining, and cattle raising (digestive processes of domestic animals) –Also comes from termites

17. Monday, 8/30/201017 Increasing concentrations of methane

18. Monday, 8/30/201018 Ozone (O 3 ) Is another important greenhouse gas Forms naturally in the stratosphere from oxygen, and warms the stratosphere Allowed life to develop over land Gets depleted over Antarctica in winter— known as the “ozone hole” Is a dangerous pollutant near Earth’s surface

19. Monday, 8/30/201019 Layers of the Atmosphere

20. Monday, 8/30/201020 Chlorofluorocarbons (CFCs) Are yet more greenhouse gases, and very powerful Do not occur naturally Are chemically stable near the surface Are broken down in the stratosphere –Loose chlorine atoms destroy stratospheric ozone Are decreasing in emissions rapidly Are decreasing in concentrations slowly

21. Monday, 8/30/201021 Global use of CFCs

22. Monday, 8/30/201022 Concentration of CFCs

23. Monday, 8/30/201023 Particles of liquid and solid in the atmosphere Are together known as aerosols [ai(e)rborne solutions] Varies in size with the type of substance Are measured in units of microns (1/1,000,000 of a meter or 1/1,000 of a mm) Most are invisible because they are so small Are more abundant over deserts Are less abundant over the oceans Are needed to form clouds Can influence climate Can be pollutants Are anthropogenic when caused by human activity

24. Monday, 8/30/201024 Particles in the atmosphere

25. Monday, 8/30/201025 Smoke from fires in Southern California viewed by satellite

26. Monday, 8/30/201026 Pressure and density in the atmosphere Pressure is force per unit area Pressure always decreases upward Pressure is related to the weight of air in a column above a particular location Density is mass per unit volume Density always decreases upward Density is related to pressure by the gas law: pressure = constant x density x temperature

27. Monday, 8/30/201027 How pressure and density decrease upward

28. Monday, 8/30/201028 Surface pressure corrected to sea level

29. Monday, 8/30/201029 Pressure in the different layers of the atmosphere